diff --git a/DemoObjCApp/AppDelegate.m b/DemoObjCApp/AppDelegate.m
index bce0eb7de..c509de00b 100644
--- a/DemoObjCApp/AppDelegate.m
+++ b/DemoObjCApp/AppDelegate.m
@@ -1,5 +1,5 @@
 /****************************************************************************
-* Copyright 2019-2020, Optimizely, Inc. and contributors                   *
+* Copyright 2019-2021, Optimizely, Inc. and contributors                   *
 *                                                                          *
 * Licensed under the Apache License, Version 2.0 (the "License");          *
 * you may not use this file except in compliance with the License.         *
@@ -24,13 +24,15 @@
 
 static NSString * const kOptimizelySdkKey = @"FCnSegiEkRry9rhVMroit4";
 static NSString * const kOptimizelyDatafileName = @"demoTestDatafile";
-static NSString * const kOptimizelyExperimentKey = @"background_experiment";
+static NSString * const kOptimizelyFeatureKey = @"decide_demo";
+static NSString * const kOptimizelyExperimentKey = @"background_experiment_decide";
 static NSString * const kOptimizelyEventKey = @"sample_conversion";
 
 @interface AppDelegate ()
 @property(nonnull, strong, nonatomic) NSString *userId;
 @property(nonnull, strong, nonatomic) NSDictionary *attributes;
 @property(nullable, strong, nonatomic) OptimizelyClient *optimizely;
+@property(nullable, strong, nonatomic) OptimizelyUserContext *user;
 @end
 
 @implementation AppDelegate
@@ -38,7 +40,7 @@ @implementation AppDelegate
 - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
     
     self.userId = [NSString stringWithFormat:@"%d", arc4random_uniform(300000)];
-    self.attributes = @{ @"browser_type": @"safari" };
+    self.attributes = @{ @"location": @"CA", @"semanticVersioning": @"1.2"};
 
     // initialize SDK in one of these two ways:
     // (1) asynchronous SDK initialization (RECOMMENDED)
@@ -134,6 +136,7 @@ -(void)initializeOptimizelySDKWithCustomization {
         
         // For sample codes for APIs, see "Samples/SamplesForAPI.swift"
         //[SamplesForAPI checkOptimizelyConfig:self.optimizely];
+        //[SamplesForAPI checkOptimizelyUserContext:self.optimizely];
     }];
 }
 
@@ -166,16 +169,16 @@ -(void)startWithRootViewController {
     dispatch_async(dispatch_get_main_queue(), ^{
         // For sample codes for other APIs, see "Samples/SamplesForAPI.m"
 
-        NSError *error;
-        NSString *variationKey = [self.optimizely activateWithExperimentKey:kOptimizelyExperimentKey
-                                                                     userId:self.userId
-                                                                 attributes:self.attributes
-                                                                      error:&error];
+        self.user = [self.optimizely createUserContextWithUserId:self.userId
+                                                      attributes:self.attributes];
+        
+        OptimizelyDecision *decision = [self.user decideWithKey:kOptimizelyFeatureKey
+                                                        options:@[@(OptimizelyDecideOptionIncludeReasons)]];
 
-        if (variationKey != nil) {
-            [self openVariationViewWithVariationKey:variationKey];
+        if (decision.variationKey != nil) {
+            [self openVariationViewWithVariationKey:decision.variationKey];
         } else {
-            NSLog(@"Optimizely SDK activation failed: %@", error.localizedDescription);
+            NSLog(@"Optimizely SDK activation failed: %@", decision.reasons);
             [self openFailureView];
         }
     });
diff --git a/DemoObjCApp/DemoObjcApp.xcodeproj/project.pbxproj b/DemoObjCApp/DemoObjcApp.xcodeproj/project.pbxproj
index 2cbbb646d..ac71754fc 100644
--- a/DemoObjCApp/DemoObjcApp.xcodeproj/project.pbxproj
+++ b/DemoObjCApp/DemoObjcApp.xcodeproj/project.pbxproj
@@ -134,6 +134,20 @@
 			remoteGlobalIDString = 6E614DCC21E3F389005982A1;
 			remoteInfo = "OptimizelySwiftSDK-tvOS";
 		};
+		6EF41A992523D23E00EAADF1 /* PBXContainerItemProxy */ = {
+			isa = PBXContainerItemProxy;
+			containerPortal = 6E4D2FE722C5457F00062EB3 /* OptimizelySwiftSDK.xcodeproj */;
+			proxyType = 2;
+			remoteGlobalIDString = BD6485812491474500F30986;
+			remoteInfo = "OptimizelySwiftSDK-macOS";
+		};
+		6EF41A9B2523D23E00EAADF1 /* PBXContainerItemProxy */ = {
+			isa = PBXContainerItemProxy;
+			containerPortal = 6E4D2FE722C5457F00062EB3 /* OptimizelySwiftSDK.xcodeproj */;
+			proxyType = 2;
+			remoteGlobalIDString = 6E14CD632423F80B00010234;
+			remoteInfo = "OptimizelyTests-Batch-iOS";
+		};
 /* End PBXContainerItemProxy section */
 
 /* Begin PBXCopyFilesBuildPhase section */
@@ -218,8 +232,10 @@
 			children = (
 				6E4D2FF722C5457F00062EB3 /* Optimizely.framework */,
 				6E4D2FF922C5457F00062EB3 /* Optimizely.framework */,
+				6EF41A9A2523D23E00EAADF1 /* Optimizely.framework */,
 				6E4D2FFB22C5457F00062EB3 /* OptimizelyTests-iOS.xctest */,
 				6E4D2FFD22C5457F00062EB3 /* OptimizelyTests-Common-iOS.xctest */,
+				6EF41A9C2523D23E00EAADF1 /* OptimizelyTests-Batch-iOS.xctest */,
 				6E4D2FFF22C5457F00062EB3 /* OptimizelyTests-APIs-iOS.xctest */,
 				6E4D300122C5457F00062EB3 /* OptimizelyTests-DataModel-iOS.xctest */,
 				6E4D300322C5457F00062EB3 /* OptimizelyTests-Others-iOS.xctest */,
@@ -403,7 +419,7 @@
 		6EF7496721E40467008B22A0 /* Project object */ = {
 			isa = PBXProject;
 			attributes = {
-				LastUpgradeCheck = 1010;
+				LastUpgradeCheck = 1200;
 				ORGANIZATIONNAME = Optimizely;
 				TargetAttributes = {
 					6EF7498D21E404BB008B22A0 = {
@@ -529,6 +545,20 @@
 			remoteRef = 6E4D300C22C5457F00062EB3 /* PBXContainerItemProxy */;
 			sourceTree = BUILT_PRODUCTS_DIR;
 		};
+		6EF41A9A2523D23E00EAADF1 /* Optimizely.framework */ = {
+			isa = PBXReferenceProxy;
+			fileType = wrapper.framework;
+			path = Optimizely.framework;
+			remoteRef = 6EF41A992523D23E00EAADF1 /* PBXContainerItemProxy */;
+			sourceTree = BUILT_PRODUCTS_DIR;
+		};
+		6EF41A9C2523D23E00EAADF1 /* OptimizelyTests-Batch-iOS.xctest */ = {
+			isa = PBXReferenceProxy;
+			fileType = wrapper.cfbundle;
+			path = "OptimizelyTests-Batch-iOS.xctest";
+			remoteRef = 6EF41A9B2523D23E00EAADF1 /* PBXContainerItemProxy */;
+			sourceTree = BUILT_PRODUCTS_DIR;
+		};
 /* End PBXReferenceProxy section */
 
 /* Begin PBXResourcesBuildPhase section */
diff --git a/DemoObjCApp/DemoObjcApp.xcodeproj/xcshareddata/xcschemes/DemoObjciOS.xcscheme b/DemoObjCApp/DemoObjcApp.xcodeproj/xcshareddata/xcschemes/DemoObjciOS.xcscheme
index 4d7d980d9..f50f01236 100644
--- a/DemoObjCApp/DemoObjcApp.xcodeproj/xcshareddata/xcschemes/DemoObjciOS.xcscheme
+++ b/DemoObjCApp/DemoObjcApp.xcodeproj/xcshareddata/xcschemes/DemoObjciOS.xcscheme
@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <Scheme
-   LastUpgradeVersion = "1130"
+   LastUpgradeVersion = "1200"
    version = "1.3">
    <BuildAction
       parallelizeBuildables = "YES"
diff --git a/DemoObjCApp/DemoObjcApp.xcodeproj/xcshareddata/xcschemes/DemoObjctvOS.xcscheme b/DemoObjCApp/DemoObjcApp.xcodeproj/xcshareddata/xcschemes/DemoObjctvOS.xcscheme
index 350477011..1027d5d68 100644
--- a/DemoObjCApp/DemoObjcApp.xcodeproj/xcshareddata/xcschemes/DemoObjctvOS.xcscheme
+++ b/DemoObjCApp/DemoObjcApp.xcodeproj/xcshareddata/xcschemes/DemoObjctvOS.xcscheme
@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <Scheme
-   LastUpgradeVersion = "1130"
+   LastUpgradeVersion = "1200"
    version = "1.3">
    <BuildAction
       parallelizeBuildables = "YES"
diff --git a/DemoObjCApp/DemoObjciOS/Base.lproj/iOSMain.storyboard b/DemoObjCApp/DemoObjciOS/Base.lproj/iOSMain.storyboard
index d9e67e68c..c5e5be578 100644
--- a/DemoObjCApp/DemoObjciOS/Base.lproj/iOSMain.storyboard
+++ b/DemoObjCApp/DemoObjciOS/Base.lproj/iOSMain.storyboard
@@ -1,10 +1,9 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<document type="com.apple.InterfaceBuilder3.CocoaTouch.Storyboard.XIB" version="3.0" toolsVersion="14490.70" targetRuntime="iOS.CocoaTouch" propertyAccessControl="none" useAutolayout="YES" useTraitCollections="YES" colorMatched="YES" initialViewController="BYZ-38-t0r">
-    <device id="retina4_7" orientation="portrait">
-        <adaptation id="fullscreen"/>
-    </device>
+<document type="com.apple.InterfaceBuilder3.CocoaTouch.Storyboard.XIB" version="3.0" toolsVersion="17156" targetRuntime="iOS.CocoaTouch" propertyAccessControl="none" useAutolayout="YES" useTraitCollections="YES" colorMatched="YES" initialViewController="BYZ-38-t0r">
+    <device id="retina4_7" orientation="portrait" appearance="light"/>
     <dependencies>
-        <plugIn identifier="com.apple.InterfaceBuilder.IBCocoaTouchPlugin" version="14490.49"/>
+        <deployment identifier="iOS"/>
+        <plugIn identifier="com.apple.InterfaceBuilder.IBCocoaTouchPlugin" version="17125"/>
         <capability name="documents saved in the Xcode 8 format" minToolsVersion="8.0"/>
     </dependencies>
     <customFonts key="customFonts">
@@ -29,15 +28,15 @@
                         <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
                         <subviews>
                             <imageView userInteractionEnabled="NO" contentMode="scaleToFill" horizontalHuggingPriority="251" verticalHuggingPriority="251" image="logo" translatesAutoresizingMaskIntoConstraints="NO" id="KSO-Tl-shb">
-                                <rect key="frame" x="96" y="244" width="183" height="178"/>
+                                <rect key="frame" x="96" y="244.5" width="183" height="178"/>
                                 <color key="backgroundColor" red="0.015686274509803921" green="0.16862745098039217" blue="0.25098039215686274" alpha="1" colorSpace="calibratedRGB"/>
                                 <color key="tintColor" red="0.015686274509803921" green="0.16862745098039217" blue="0.25098039215686274" alpha="1" colorSpace="calibratedRGB"/>
                             </imageView>
                         </subviews>
                         <color key="backgroundColor" red="0.015686274509803921" green="0.16862745098039217" blue="0.25098039215686274" alpha="1" colorSpace="calibratedRGB"/>
                         <constraints>
-                            <constraint firstItem="KSO-Tl-shb" firstAttribute="top" secondItem="y3c-jy-aDJ" secondAttribute="bottom" constant="224" id="ECF-s4-cSj"/>
                             <constraint firstItem="KSO-Tl-shb" firstAttribute="centerX" secondItem="8bC-Xf-vdC" secondAttribute="centerX" id="fj6-Iy-Xle"/>
+                            <constraint firstItem="KSO-Tl-shb" firstAttribute="centerY" secondItem="8bC-Xf-vdC" secondAttribute="centerY" id="jGY-EN-jGI"/>
                         </constraints>
                     </view>
                 </viewController>
@@ -54,14 +53,14 @@
                         <viewControllerLayoutGuide type="bottom" id="41k-LG-Ek5"/>
                     </layoutGuides>
                     <view key="view" contentMode="scaleToFill" id="Iok-Jh-ZED">
-                        <rect key="frame" x="0.0" y="0.0" width="375" height="667"/>
+                        <rect key="frame" x="0.0" y="0.0" width="375" height="647"/>
                         <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
                         <subviews>
                             <imageView userInteractionEnabled="NO" contentMode="scaleToFill" horizontalHuggingPriority="251" verticalHuggingPriority="251" restorationIdentifier="FailureImageView" image="background_error" translatesAutoresizingMaskIntoConstraints="NO" id="QKm-lz-bUE">
-                                <rect key="frame" x="0.0" y="0.0" width="375" height="667"/>
+                                <rect key="frame" x="0.0" y="0.0" width="375" height="647"/>
                             </imageView>
                             <textView clipsSubviews="YES" multipleTouchEnabled="YES" contentMode="scaleToFill" fixedFrame="YES" editable="NO" text="Oops! Let's try this again." textAlignment="center" translatesAutoresizingMaskIntoConstraints="NO" id="iKU-z4-P8h">
-                                <rect key="frame" x="82" y="315" width="211" height="58"/>
+                                <rect key="frame" x="82" y="305" width="211" height="58"/>
                                 <autoresizingMask key="autoresizingMask" flexibleMinX="YES" flexibleMaxX="YES" flexibleMinY="YES" flexibleMaxY="YES"/>
                                 <color key="backgroundColor" white="0.0" alpha="0.0" colorSpace="calibratedWhite"/>
                                 <color key="textColor" red="1" green="1" blue="1" alpha="1" colorSpace="calibratedRGB"/>
@@ -97,24 +96,24 @@
                             <imageView userInteractionEnabled="NO" contentMode="scaleToFill" horizontalHuggingPriority="251" verticalHuggingPriority="251" translatesAutoresizingMaskIntoConstraints="NO" id="ZDA-v7-RgX">
                                 <rect key="frame" x="0.0" y="0.0" width="375" height="667"/>
                             </imageView>
-                            <label opaque="NO" userInteractionEnabled="NO" contentMode="left" horizontalHuggingPriority="251" verticalHuggingPriority="251" fixedFrame="YES" text="A" textAlignment="center" lineBreakMode="tailTruncation" baselineAdjustment="alignBaselines" adjustsFontSizeToFit="NO" translatesAutoresizingMaskIntoConstraints="NO" id="GuL-M1-dn2">
-                                <rect key="frame" x="123" y="253" width="128" height="125"/>
-                                <autoresizingMask key="autoresizingMask" flexibleMinX="YES" flexibleMaxX="YES" flexibleMinY="YES" flexibleMaxY="YES"/>
+                            <label opaque="NO" userInteractionEnabled="NO" contentMode="left" horizontalHuggingPriority="251" verticalHuggingPriority="251" text="A" textAlignment="center" lineBreakMode="tailTruncation" baselineAdjustment="alignBaselines" adjustsFontSizeToFit="NO" translatesAutoresizingMaskIntoConstraints="NO" id="GuL-M1-dn2">
+                                <rect key="frame" x="140" y="224" width="95" height="144"/>
                                 <fontDescription key="fontDescription" name="ProximaNova-Regular" family="Proxima Nova" pointSize="144"/>
                                 <nil key="textColor"/>
                                 <nil key="highlightedColor"/>
                             </label>
-                            <label opaque="NO" userInteractionEnabled="NO" contentMode="left" horizontalHuggingPriority="251" verticalHuggingPriority="251" fixedFrame="YES" text="VARIATION" textAlignment="center" lineBreakMode="tailTruncation" baselineAdjustment="alignBaselines" adjustsFontSizeToFit="NO" translatesAutoresizingMaskIntoConstraints="NO" id="8CQ-8i-O97">
-                                <rect key="frame" x="126" y="371" width="123" height="21"/>
-                                <autoresizingMask key="autoresizingMask" flexibleMinX="YES" flexibleMaxX="YES" flexibleMinY="YES" flexibleMaxY="YES"/>
+                            <label opaque="NO" userInteractionEnabled="NO" contentMode="left" horizontalHuggingPriority="251" verticalHuggingPriority="251" text="VARIATION" textAlignment="center" lineBreakMode="tailTruncation" baselineAdjustment="alignBaselines" adjustsFontSizeToFit="NO" translatesAutoresizingMaskIntoConstraints="NO" id="8CQ-8i-O97">
+                                <rect key="frame" x="127" y="372" width="120" height="24"/>
                                 <fontDescription key="fontDescription" name="ProximaNova-Regular" family="Proxima Nova" pointSize="24"/>
                                 <nil key="textColor"/>
                                 <nil key="highlightedColor"/>
                             </label>
-                            <button opaque="NO" contentMode="scaleToFill" fixedFrame="YES" contentHorizontalAlignment="center" contentVerticalAlignment="center" buttonType="roundedRect" lineBreakMode="middleTruncation" translatesAutoresizingMaskIntoConstraints="NO" id="eHj-DU-rky">
-                                <rect key="frame" x="106" y="424" width="162" height="36"/>
-                                <autoresizingMask key="autoresizingMask" flexibleMinX="YES" flexibleMaxX="YES" flexibleMinY="YES" flexibleMaxY="YES"/>
+                            <button opaque="NO" contentMode="scaleToFill" contentHorizontalAlignment="center" contentVerticalAlignment="center" buttonType="system" lineBreakMode="middleTruncation" translatesAutoresizingMaskIntoConstraints="NO" id="eHj-DU-rky">
+                                <rect key="frame" x="66" y="446" width="243" height="50"/>
                                 <color key="backgroundColor" red="0.97647058819999999" green="0.039215686270000001" blue="0.054901960780000002" alpha="1" colorSpace="calibratedRGB"/>
+                                <constraints>
+                                    <constraint firstAttribute="height" constant="50" id="ySb-qZ-8fB"/>
+                                </constraints>
                                 <fontDescription key="fontDescription" name="Roboto-Medium" family="Roboto" pointSize="14"/>
                                 <state key="normal" title="TEST CONVERSION">
                                     <color key="titleColor" white="1" alpha="1" colorSpace="calibratedWhite"/>
@@ -127,9 +126,16 @@
                         </subviews>
                         <color key="backgroundColor" white="1" alpha="1" colorSpace="calibratedWhite"/>
                         <constraints>
+                            <constraint firstItem="8CQ-8i-O97" firstAttribute="firstBaseline" secondItem="GuL-M1-dn2" secondAttribute="baseline" constant="52" symbolType="layoutAnchor" id="7sd-PS-OVN"/>
+                            <constraint firstItem="8CQ-8i-O97" firstAttribute="centerY" secondItem="Pxf-lJ-vhB" secondAttribute="centerY" constant="50" id="99f-Vr-zGi"/>
+                            <constraint firstItem="GuL-M1-dn2" firstAttribute="centerX" secondItem="Pxf-lJ-vhB" secondAttribute="centerX" id="BSr-2V-oKk"/>
                             <constraint firstItem="WeV-sX-2WA" firstAttribute="top" secondItem="ZDA-v7-RgX" secondAttribute="bottom" id="CrG-tN-JNQ"/>
+                            <constraint firstItem="8CQ-8i-O97" firstAttribute="centerX" secondItem="Pxf-lJ-vhB" secondAttribute="centerX" id="OyZ-oF-LZL"/>
                             <constraint firstItem="ZDA-v7-RgX" firstAttribute="leading" secondItem="Pxf-lJ-vhB" secondAttribute="leading" id="WBH-qa-3f2"/>
                             <constraint firstItem="ZDA-v7-RgX" firstAttribute="top" secondItem="Pxf-lJ-vhB" secondAttribute="top" id="bCE-xf-Orz"/>
+                            <constraint firstItem="eHj-DU-rky" firstAttribute="centerX" secondItem="Pxf-lJ-vhB" secondAttribute="centerX" id="hGv-c7-t5t"/>
+                            <constraint firstItem="eHj-DU-rky" firstAttribute="top" secondItem="8CQ-8i-O97" secondAttribute="bottom" constant="50" id="iRl-1Z-5Ix"/>
+                            <constraint firstItem="eHj-DU-rky" firstAttribute="leading" secondItem="Pxf-lJ-vhB" secondAttribute="leadingMargin" constant="50" id="ifO-O7-b59"/>
                             <constraint firstAttribute="trailing" secondItem="ZDA-v7-RgX" secondAttribute="trailing" id="kId-8h-KkR"/>
                         </constraints>
                     </view>
@@ -154,21 +160,21 @@
                         <viewControllerLayoutGuide type="bottom" id="ARR-Gc-cn2"/>
                     </layoutGuides>
                     <view key="view" contentMode="scaleToFill" id="yBM-xo-e29">
-                        <rect key="frame" x="0.0" y="0.0" width="375" height="667"/>
+                        <rect key="frame" x="0.0" y="0.0" width="375" height="647"/>
                         <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
                         <subviews>
                             <imageView userInteractionEnabled="NO" contentMode="scaleToFill" horizontalHuggingPriority="251" verticalHuggingPriority="251" restorationIdentifier="ConversionSuccessImageView" image="background_confirmation" translatesAutoresizingMaskIntoConstraints="NO" id="GEt-Bf-Es2">
-                                <rect key="frame" x="0.0" y="0.0" width="375" height="667"/>
+                                <rect key="frame" x="0.0" y="0.0" width="375" height="647"/>
                             </imageView>
                             <textView clipsSubviews="YES" multipleTouchEnabled="YES" contentMode="scaleToFill" editable="NO" text="Conversion event recorded to Optimizely." textAlignment="center" selectable="NO" translatesAutoresizingMaskIntoConstraints="NO" id="CRh-TJ-NCw">
-                                <rect key="frame" x="94" y="139" width="187.5" height="166.5"/>
+                                <rect key="frame" x="94" y="135" width="187.5" height="161.5"/>
                                 <color key="backgroundColor" white="0.0" alpha="0.0" colorSpace="calibratedWhite"/>
                                 <color key="textColor" red="0.019607843137254902" green="0.16862745098039217" blue="0.25490196078431371" alpha="1" colorSpace="calibratedRGB"/>
                                 <fontDescription key="fontDescription" name="ProximaNova-Regular" family="Proxima Nova" pointSize="24"/>
                                 <textInputTraits key="textInputTraits" autocapitalizationType="sentences"/>
                             </textView>
-                            <button opaque="NO" contentMode="scaleToFill" contentHorizontalAlignment="center" contentVerticalAlignment="center" buttonType="roundedRect" lineBreakMode="middleTruncation" translatesAutoresizingMaskIntoConstraints="NO" id="Qje-MN-IfM">
-                                <rect key="frame" x="149.5" y="426" width="76" height="37"/>
+                            <button opaque="NO" contentMode="scaleToFill" contentHorizontalAlignment="center" contentVerticalAlignment="center" buttonType="system" lineBreakMode="middleTruncation" translatesAutoresizingMaskIntoConstraints="NO" id="Qje-MN-IfM">
+                                <rect key="frame" x="149.5" y="413" width="76" height="37"/>
                                 <color key="backgroundColor" red="0.97647058819999999" green="0.039215686270000001" blue="0.054901960780000002" alpha="1" colorSpace="calibratedRGB"/>
                                 <fontDescription key="fontDescription" name="Roboto-Medium" family="Roboto" pointSize="14"/>
                                 <inset key="contentEdgeInsets" minX="20" minY="10" maxX="20" maxY="10"/>
diff --git a/DemoObjCApp/Samples/SamplesForAPI.h b/DemoObjCApp/Samples/SamplesForAPI.h
index 647de1522..254773712 100644
--- a/DemoObjCApp/Samples/SamplesForAPI.h
+++ b/DemoObjCApp/Samples/SamplesForAPI.h
@@ -1,6 +1,6 @@
 //
 /****************************************************************************
-* Copyright 2019, Optimizely, Inc. and contributors                        *
+* Copyright 2019,2021, Optimizely, Inc. and contributors                   *
 *                                                                          *
 * Licensed under the Apache License, Version 2.0 (the "License");          *
 * you may not use this file except in compliance with the License.         *
@@ -25,6 +25,7 @@ NS_ASSUME_NONNULL_BEGIN
 @interface SamplesForAPI: NSObject
 +(void)checkAPIs:(OptimizelyClient*)optimizely;
 +(void)checkOptimizelyConfig:(OptimizelyClient*)optimizely;
++(void)checkOptimizelyUserContext:(OptimizelyClient*)optimizely;
 @end
 
 NS_ASSUME_NONNULL_END
diff --git a/DemoObjCApp/Samples/SamplesForAPI.m b/DemoObjCApp/Samples/SamplesForAPI.m
index bc9e0ce14..91f267896 100644
--- a/DemoObjCApp/Samples/SamplesForAPI.m
+++ b/DemoObjCApp/Samples/SamplesForAPI.m
@@ -1,6 +1,6 @@
 //
 /****************************************************************************
- * Copyright 2019, Optimizely, Inc. and contributors                        *
+ * Copyright 2019,2021, Optimizely, Inc. and contributors                   *
  *                                                                          *
  * Licensed under the Apache License, Version 2.0 (the "License");          *
  * you may not use this file except in compliance with the License.         *
@@ -131,6 +131,45 @@ +(void)checkAPIs:(OptimizelyClient*)optimizely {
     }
 }
 
+// MARK: - OptimizelyUserContext
+
++(void)checkOptimizelyUserContext:(OptimizelyClient*)optimizely {
+    NSDictionary *attributes = @{
+                                 @"location": @"NY",
+                                 @"device": @"iPhone",
+                                 @"lifetime": @24738388,
+                                 @"is_logged_in": @true
+                                 };
+    
+    NSDictionary *tags = @{
+                           @"category" : @"shoes",
+                           @"count": @5
+                           };
+
+    OptimizelyUserContext *user = [optimizely createUserContextWithUserId:@"user_123" attributes:attributes];
+    
+    OptimizelyDecision *decision = [user decideWithKey:@"show_coupon" options:@[@(OptimizelyDecideOptionIncludeReasons)]];
+    
+    if (decision.variationKey != nil) {
+        NSLog(@"[decide] flag decision to variation: %@", decision.variationKey);
+        NSLog(@"[decide] flag enabled: %d with variables: %@)", decision.enabled, [decision.variables toMap]);
+        NSLog(@"[decide] reasons: %@", decision.reasons);
+    } else {
+        NSLog(@"[decide] error: %@", decision.reasons);
+    }
+    
+    NSError *error = nil;
+    BOOL success = [user trackEventWithEventKey:@"my_purchase_event_key"
+                                      eventTags:tags
+                                          error:&error];
+    if (success) {
+        NSLog(@"Error: %@", error);
+        NSLog(@"[track] success");
+    } else {
+        NSLog(@"[decide] error: %@", error.localizedDescription);
+    }
+}
+
 // MARK: - OptimizelyConfig
 
 +(void)checkOptimizelyConfig:(OptimizelyClient*)optimizely {
diff --git a/DemoSwiftApp/AppDelegate.swift b/DemoSwiftApp/AppDelegate.swift
index 499b6ff23..961fd1ce5 100644
--- a/DemoSwiftApp/AppDelegate.swift
+++ b/DemoSwiftApp/AppDelegate.swift
@@ -1,5 +1,5 @@
 /****************************************************************************
-* Copyright 2019-2020, Optimizely, Inc. and contributors                   *
+* Copyright 2019-2021, Optimizely, Inc. and contributors                   *
 *                                                                          *
 * Licensed under the Apache License, Version 2.0 (the "License");          *
 * you may not use this file except in compliance with the License.         *
@@ -23,14 +23,19 @@ class AppDelegate: UIResponder, UIApplicationDelegate {
 
     let sdkKey = "FCnSegiEkRry9rhVMroit4"
     let datafileName = "demoTestDatafile"
-    let experimentKey = "background_experiment"
+    let featureKey = "decide_demo"
+    let experimentKey = "background_experiment_decide"
     let eventKey = "sample_conversion"
 
     let userId = String(Int.random(in: 0..<100000))
-    let attributes: [String: Any?] = ["browser_type": "safari", "bool_attr": false]
+    let attributes: [String: Any] = ["location": "NY",
+                                     "bool_attr": false,
+                                     "semanticVersioning": "1.2"]
 
     var window: UIWindow?
     var optimizely: OptimizelyClient!
+    var user: OptimizelyUserContext!
+    
     var storyboard: UIStoryboard {
         #if os(iOS)
         return UIStoryboard(name: "iOSMain", bundle: nil)
@@ -125,6 +130,7 @@ class AppDelegate: UIResponder, UIApplicationDelegate {
             
             // For sample codes for APIs, see "Samples/SamplesForAPI.swift"
             //SamplesForAPI.checkOptimizelyConfig(optimizely: self.optimizely)
+            //SamplesForAPI.checkOptimizelyUserContext(optimizely: self.optimizely)
         }
     }
     
@@ -140,7 +146,7 @@ class AppDelegate: UIResponder, UIApplicationDelegate {
             print("Received track notification: \(eventKey) \(userId) \(String(describing: attributes)) \(String(describing: eventTags)) \(event)")
         })
 
-        _ = notificationCenter.addDatafileChangeNotificationListener(datafileListener: { (_) in
+        _ = notificationCenter.addDatafileChangeNotificationListener(datafileListener: { _ in
             DispatchQueue.main.async {
                 #if os(iOS)
                 if let controller = self.window?.rootViewController {
@@ -153,9 +159,8 @@ class AppDelegate: UIResponder, UIApplicationDelegate {
                 #endif
 
                 if let controller = self.window?.rootViewController as? VariationViewController {
-                    //controller.showCoupon = toggle == FeatureFlagToggle.on ? true : false;
-                    controller.showCoupon = self.optimizely.isFeatureEnabled(featureKey: "show_coupon",
-                                                                             userId: self.userId)
+                    let decision = self.user.decide(key: "show_coupon")
+                    controller.showCoupon = decision.enabled
                 }
             }
             
@@ -173,16 +178,13 @@ class AppDelegate: UIResponder, UIApplicationDelegate {
 
     func startWithRootViewController() {
         DispatchQueue.main.async {
-            do {
-                let variationKey = try self.optimizely.activate(experimentKey: self.experimentKey,
-                                                           userId: self.userId,
-                                                           attributes: self.attributes)
+            self.user = self.optimizely.createUserContext(userId: self.userId,
+                                                          attributes: self.attributes)
+            let decision = self.user.decide(key: self.featureKey, options: [.includeReasons])
+            if let variationKey = decision.variationKey {
                 self.openVariationView(variationKey: variationKey)
-            } catch OptimizelyError.variationUnknown(self.userId, self.experimentKey) {
-                print("Optimizely SDK activation cannot map this user to experiemnt")
-                self.openVariationView(variationKey: nil)
-            } catch {
-                print("Optimizely SDK activation failed: \(error)")
+            } else {
+                print("Optimizely SDK decision failed: \(decision.reasons)")
                 self.openFailureView()
             }
         }
@@ -192,8 +194,9 @@ class AppDelegate: UIResponder, UIApplicationDelegate {
         if let variationViewController = storyboard.instantiateViewController(withIdentifier: "VariationViewController")
             as? VariationViewController {
 
-            variationViewController.showCoupon = optimizely.isFeatureEnabled(featureKey: "show_coupon",
-                                                                         userId: userId)
+            let decision = self.user.decide(key: "show_coupon")
+            variationViewController.showCoupon = decision.enabled
+
             variationViewController.optimizely = optimizely
             variationViewController.userId = userId
             variationViewController.variationKey = variationKey
diff --git a/DemoSwiftApp/DemoSwiftApp.xcodeproj/project.pbxproj b/DemoSwiftApp/DemoSwiftApp.xcodeproj/project.pbxproj
index d65c1ef53..03c05246b 100644
--- a/DemoSwiftApp/DemoSwiftApp.xcodeproj/project.pbxproj
+++ b/DemoSwiftApp/DemoSwiftApp.xcodeproj/project.pbxproj
@@ -11,7 +11,6 @@
 		25C6F3B721C95D1800C2EBDD /* AppDelegate.swift in Sources */ = {isa = PBXBuildFile; fileRef = EA299EE21E55313B00931399 /* AppDelegate.swift */; };
 		25C6F3BC21C95D2100C2EBDD /* VariationViewController.swift in Sources */ = {isa = PBXBuildFile; fileRef = EA299EE51E55313B00931399 /* VariationViewController.swift */; };
 		25C6F3BD21C95D2100C2EBDD /* VariationViewController.swift in Sources */ = {isa = PBXBuildFile; fileRef = EA299EE51E55313B00931399 /* VariationViewController.swift */; };
-		25C6F3BF21C95D4800C2EBDD /* iOSMain.storyboard in Resources */ = {isa = PBXBuildFile; fileRef = EA299EDD1E55312200931399 /* iOSMain.storyboard */; };
 		5015D17687408F548F31F1A6 /* Pods_DemoSwifttvOS.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = CCC404BE4046CDA1D3A9C26B /* Pods_DemoSwifttvOS.framework */; };
 		6E4D2FDF22C5455400062EB3 /* Optimizely.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = 6E4D2FC822C5454400062EB3 /* Optimizely.framework */; };
 		6E4D2FE022C5455400062EB3 /* Optimizely.framework in Embed Frameworks */ = {isa = PBXBuildFile; fileRef = 6E4D2FC822C5454400062EB3 /* Optimizely.framework */; settings = {ATTRIBUTES = (CodeSignOnCopy, RemoveHeadersOnCopy, ); }; };
@@ -25,6 +24,7 @@
 		6E96819E21EEA391009B7FEC /* ProximaNova-Regular.otf in Resources */ = {isa = PBXBuildFile; fileRef = 6E96819421EEA391009B7FEC /* ProximaNova-Regular.otf */; };
 		6E96819F21EEA3B3009B7FEC /* Assets.xcassets in Resources */ = {isa = PBXBuildFile; fileRef = 6E96819021EEA391009B7FEC /* Assets.xcassets */; };
 		6E9681A021EEA3B7009B7FEC /* Assets.xcassets in Resources */ = {isa = PBXBuildFile; fileRef = 6E96818E21EEA391009B7FEC /* Assets.xcassets */; };
+		6E9FC9BA2548E1B7006AD345 /* iOSMain.storyboard in Resources */ = {isa = PBXBuildFile; fileRef = EA299EDD1E55312200931399 /* iOSMain.storyboard */; };
 		6EDBCE0022710E87009DF724 /* CustomLogger.swift in Sources */ = {isa = PBXBuildFile; fileRef = 6EDBCDF522710E87009DF724 /* CustomLogger.swift */; };
 		6EDBCE0122710E87009DF724 /* CustomLogger.swift in Sources */ = {isa = PBXBuildFile; fileRef = 6EDBCDF522710E87009DF724 /* CustomLogger.swift */; };
 		6EF2CF1D21E4158A00A5D78D /* tvOSMain.storyboard in Resources */ = {isa = PBXBuildFile; fileRef = 6EF2CF1B21E4158A00A5D78D /* tvOSMain.storyboard */; };
@@ -132,6 +132,20 @@
 			remoteGlobalIDString = 6E614DCC21E3F389005982A1;
 			remoteInfo = "OptimizelySwiftSDK-tvOS";
 		};
+		6EF41A892523D22C00EAADF1 /* PBXContainerItemProxy */ = {
+			isa = PBXContainerItemProxy;
+			containerPortal = 6E4D2FB822C5454400062EB3 /* OptimizelySwiftSDK.xcodeproj */;
+			proxyType = 2;
+			remoteGlobalIDString = BD6485812491474500F30986;
+			remoteInfo = "OptimizelySwiftSDK-macOS";
+		};
+		6EF41A8B2523D22C00EAADF1 /* PBXContainerItemProxy */ = {
+			isa = PBXContainerItemProxy;
+			containerPortal = 6E4D2FB822C5454400062EB3 /* OptimizelySwiftSDK.xcodeproj */;
+			proxyType = 2;
+			remoteGlobalIDString = 6E14CD632423F80B00010234;
+			remoteInfo = "OptimizelyTests-Batch-iOS";
+		};
 /* End PBXContainerItemProxy section */
 
 /* Begin PBXCopyFilesBuildPhase section */
@@ -222,8 +236,10 @@
 			children = (
 				6E4D2FC822C5454400062EB3 /* Optimizely.framework */,
 				6E4D2FCA22C5454400062EB3 /* Optimizely.framework */,
+				6EF41A8A2523D22C00EAADF1 /* Optimizely.framework */,
 				6E4D2FCC22C5454400062EB3 /* OptimizelyTests-iOS.xctest */,
 				6E4D2FCE22C5454400062EB3 /* OptimizelyTests-Common-iOS.xctest */,
+				6EF41A8C2523D22C00EAADF1 /* OptimizelyTests-Batch-iOS.xctest */,
 				6E4D2FD022C5454400062EB3 /* OptimizelyTests-APIs-iOS.xctest */,
 				6E4D2FD222C5454400062EB3 /* OptimizelyTests-DataModel-iOS.xctest */,
 				6E4D2FD422C5454400062EB3 /* OptimizelyTests-Others-iOS.xctest */,
@@ -393,7 +409,7 @@
 			isa = PBXProject;
 			attributes = {
 				LastSwiftUpdateCheck = 1010;
-				LastUpgradeCheck = 1130;
+				LastUpgradeCheck = 1200;
 				ORGANIZATIONNAME = Optimizely;
 				TargetAttributes = {
 					252D7DEC21C8800800134A7A = {
@@ -526,6 +542,20 @@
 			remoteRef = 6E4D2FDD22C5454400062EB3 /* PBXContainerItemProxy */;
 			sourceTree = BUILT_PRODUCTS_DIR;
 		};
+		6EF41A8A2523D22C00EAADF1 /* Optimizely.framework */ = {
+			isa = PBXReferenceProxy;
+			fileType = wrapper.framework;
+			path = Optimizely.framework;
+			remoteRef = 6EF41A892523D22C00EAADF1 /* PBXContainerItemProxy */;
+			sourceTree = BUILT_PRODUCTS_DIR;
+		};
+		6EF41A8C2523D22C00EAADF1 /* OptimizelyTests-Batch-iOS.xctest */ = {
+			isa = PBXReferenceProxy;
+			fileType = wrapper.cfbundle;
+			path = "OptimizelyTests-Batch-iOS.xctest";
+			remoteRef = 6EF41A8B2523D22C00EAADF1 /* PBXContainerItemProxy */;
+			sourceTree = BUILT_PRODUCTS_DIR;
+		};
 /* End PBXReferenceProxy section */
 
 /* Begin PBXResourcesBuildPhase section */
@@ -535,8 +565,8 @@
 			files = (
 				6E96819B21EEA391009B7FEC /* demoTestDatafile.json in Resources */,
 				6E96819921EEA391009B7FEC /* Roboto-Medium.ttf in Resources */,
-				25C6F3BF21C95D4800C2EBDD /* iOSMain.storyboard in Resources */,
 				6E96819F21EEA3B3009B7FEC /* Assets.xcassets in Resources */,
+				6E9FC9BA2548E1B7006AD345 /* iOSMain.storyboard in Resources */,
 				6E96819D21EEA391009B7FEC /* ProximaNova-Regular.otf in Resources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
diff --git a/DemoSwiftApp/DemoSwiftApp.xcodeproj/xcshareddata/xcschemes/DemoSwiftiOS.xcscheme b/DemoSwiftApp/DemoSwiftApp.xcodeproj/xcshareddata/xcschemes/DemoSwiftiOS.xcscheme
index 6b5b8de4f..c59bd36fb 100644
--- a/DemoSwiftApp/DemoSwiftApp.xcodeproj/xcshareddata/xcschemes/DemoSwiftiOS.xcscheme
+++ b/DemoSwiftApp/DemoSwiftApp.xcodeproj/xcshareddata/xcschemes/DemoSwiftiOS.xcscheme
@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <Scheme
-   LastUpgradeVersion = "1130"
+   LastUpgradeVersion = "1200"
    version = "1.3">
    <BuildAction
       parallelizeBuildables = "YES"
diff --git a/DemoSwiftApp/DemoSwiftApp.xcodeproj/xcshareddata/xcschemes/DemoSwifttvOS.xcscheme b/DemoSwiftApp/DemoSwiftApp.xcodeproj/xcshareddata/xcschemes/DemoSwifttvOS.xcscheme
index 37a139a37..652a8460a 100644
--- a/DemoSwiftApp/DemoSwiftApp.xcodeproj/xcshareddata/xcschemes/DemoSwifttvOS.xcscheme
+++ b/DemoSwiftApp/DemoSwiftApp.xcodeproj/xcshareddata/xcschemes/DemoSwifttvOS.xcscheme
@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <Scheme
-   LastUpgradeVersion = "1130"
+   LastUpgradeVersion = "1200"
    version = "1.3">
    <BuildAction
       parallelizeBuildables = "YES"
diff --git a/DemoSwiftApp/DemoSwiftiOS/Base.lproj/iOSMain.storyboard b/DemoSwiftApp/DemoSwiftiOS/Base.lproj/iOSMain.storyboard
index 0f00be617..cec333244 100644
--- a/DemoSwiftApp/DemoSwiftiOS/Base.lproj/iOSMain.storyboard
+++ b/DemoSwiftApp/DemoSwiftiOS/Base.lproj/iOSMain.storyboard
@@ -1,11 +1,9 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<document type="com.apple.InterfaceBuilder3.CocoaTouch.Storyboard.XIB" version="3.0" toolsVersion="14490.70" targetRuntime="iOS.CocoaTouch" propertyAccessControl="none" useAutolayout="YES" useTraitCollections="YES" colorMatched="YES" initialViewController="BYZ-38-t0r">
-    <device id="retina4_7" orientation="portrait">
-        <adaptation id="fullscreen"/>
-    </device>
+<document type="com.apple.InterfaceBuilder3.CocoaTouch.Storyboard.XIB" version="3.0" toolsVersion="17156" targetRuntime="iOS.CocoaTouch" propertyAccessControl="none" useAutolayout="YES" useTraitCollections="YES" colorMatched="YES" initialViewController="BYZ-38-t0r">
+    <device id="retina4_7" orientation="portrait" appearance="light"/>
     <dependencies>
         <deployment identifier="iOS"/>
-        <plugIn identifier="com.apple.InterfaceBuilder.IBCocoaTouchPlugin" version="14490.49"/>
+        <plugIn identifier="com.apple.InterfaceBuilder.IBCocoaTouchPlugin" version="17125"/>
         <capability name="documents saved in the Xcode 8 format" minToolsVersion="8.0"/>
     </dependencies>
     <customFonts key="customFonts">
@@ -30,14 +28,14 @@
                         <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
                         <subviews>
                             <imageView userInteractionEnabled="NO" contentMode="scaleToFill" horizontalHuggingPriority="251" verticalHuggingPriority="251" image="logo" translatesAutoresizingMaskIntoConstraints="NO" id="KSO-Tl-shb">
-                                <rect key="frame" x="96" y="244" width="183" height="178"/>
+                                <rect key="frame" x="96" y="244.5" width="183" height="178"/>
                                 <color key="backgroundColor" red="0.015686274509803921" green="0.16862745098039217" blue="0.25098039215686274" alpha="1" colorSpace="calibratedRGB"/>
                                 <color key="tintColor" red="0.015686274509803921" green="0.16862745098039217" blue="0.25098039215686274" alpha="1" colorSpace="calibratedRGB"/>
                             </imageView>
                         </subviews>
                         <color key="backgroundColor" red="0.015686274509803921" green="0.16862745098039217" blue="0.25098039215686274" alpha="1" colorSpace="calibratedRGB"/>
                         <constraints>
-                            <constraint firstItem="KSO-Tl-shb" firstAttribute="top" secondItem="y3c-jy-aDJ" secondAttribute="bottom" constant="224" id="ECF-s4-cSj"/>
+                            <constraint firstItem="KSO-Tl-shb" firstAttribute="centerY" secondItem="8bC-Xf-vdC" secondAttribute="centerY" id="WaT-n8-OYy"/>
                             <constraint firstItem="KSO-Tl-shb" firstAttribute="centerX" secondItem="8bC-Xf-vdC" secondAttribute="centerX" id="fj6-Iy-Xle"/>
                         </constraints>
                     </view>
@@ -55,14 +53,14 @@
                         <viewControllerLayoutGuide type="bottom" id="41k-LG-Ek5"/>
                     </layoutGuides>
                     <view key="view" contentMode="scaleToFill" id="Iok-Jh-ZED">
-                        <rect key="frame" x="0.0" y="0.0" width="375" height="667"/>
+                        <rect key="frame" x="0.0" y="0.0" width="375" height="647"/>
                         <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
                         <subviews>
                             <imageView userInteractionEnabled="NO" contentMode="scaleToFill" horizontalHuggingPriority="251" verticalHuggingPriority="251" restorationIdentifier="FailureImageView" image="background_error" translatesAutoresizingMaskIntoConstraints="NO" id="QKm-lz-bUE">
-                                <rect key="frame" x="0.0" y="0.0" width="375" height="667"/>
+                                <rect key="frame" x="0.0" y="0.0" width="375" height="647"/>
                             </imageView>
                             <textView clipsSubviews="YES" multipleTouchEnabled="YES" contentMode="scaleToFill" fixedFrame="YES" editable="NO" text="Oops! Let's try this again." textAlignment="center" translatesAutoresizingMaskIntoConstraints="NO" id="iKU-z4-P8h">
-                                <rect key="frame" x="82" y="315" width="211" height="58"/>
+                                <rect key="frame" x="82" y="305" width="211" height="58"/>
                                 <autoresizingMask key="autoresizingMask" flexibleMinX="YES" flexibleMaxX="YES" flexibleMinY="YES" flexibleMaxY="YES"/>
                                 <color key="backgroundColor" white="0.0" alpha="0.0" colorSpace="calibratedWhite"/>
                                 <color key="textColor" red="1" green="1" blue="1" alpha="1" colorSpace="calibratedRGB"/>
@@ -99,7 +97,7 @@
                                 <rect key="frame" x="0.0" y="0.0" width="375" height="667"/>
                             </imageView>
                             <label opaque="NO" userInteractionEnabled="NO" contentMode="left" horizontalHuggingPriority="251" verticalHuggingPriority="251" text="A" textAlignment="center" lineBreakMode="tailTruncation" baselineAdjustment="alignBaselines" adjustsFontSizeToFit="NO" translatesAutoresizingMaskIntoConstraints="NO" id="GuL-M1-dn2">
-                                <rect key="frame" x="123.5" y="253" width="128" height="125"/>
+                                <rect key="frame" x="123.5" y="207.5" width="128" height="144"/>
                                 <constraints>
                                     <constraint firstAttribute="width" constant="128" id="RRZ-tK-QO5"/>
                                 </constraints>
@@ -108,13 +106,13 @@
                                 <nil key="highlightedColor"/>
                             </label>
                             <label opaque="NO" userInteractionEnabled="NO" contentMode="left" horizontalHuggingPriority="251" verticalHuggingPriority="251" text="VARIATION" textAlignment="center" lineBreakMode="tailTruncation" baselineAdjustment="alignBaselines" adjustsFontSizeToFit="NO" translatesAutoresizingMaskIntoConstraints="NO" id="8CQ-8i-O97">
-                                <rect key="frame" x="127.5" y="368" width="120" height="24"/>
+                                <rect key="frame" x="127.5" y="371.5" width="120" height="24"/>
                                 <fontDescription key="fontDescription" name="ProximaNova-Regular" family="Proxima Nova" pointSize="24"/>
                                 <nil key="textColor"/>
                                 <nil key="highlightedColor"/>
                             </label>
-                            <button opaque="NO" contentMode="scaleToFill" contentHorizontalAlignment="center" contentVerticalAlignment="center" buttonType="roundedRect" lineBreakMode="middleTruncation" translatesAutoresizingMaskIntoConstraints="NO" id="eHj-DU-rky">
-                                <rect key="frame" x="106" y="424" width="163" height="36"/>
+                            <button opaque="NO" contentMode="scaleToFill" contentHorizontalAlignment="center" contentVerticalAlignment="center" buttonType="system" lineBreakMode="middleTruncation" translatesAutoresizingMaskIntoConstraints="NO" id="eHj-DU-rky">
+                                <rect key="frame" x="66" y="445.5" width="243" height="36"/>
                                 <color key="backgroundColor" red="0.97647058819999999" green="0.039215686270000001" blue="0.054901960780000002" alpha="1" colorSpace="calibratedRGB"/>
                                 <constraints>
                                     <constraint firstAttribute="height" constant="36" id="oWi-Rn-QiX"/>
@@ -132,17 +130,15 @@
                                 <rect key="frame" x="0.0" y="0.0" width="375" height="667"/>
                                 <subviews>
                                     <label opaque="NO" userInteractionEnabled="NO" contentMode="left" horizontalHuggingPriority="251" verticalHuggingPriority="251" text="Take 100% off" textAlignment="center" lineBreakMode="tailTruncation" baselineAdjustment="alignBaselines" adjustsFontSizeToFit="NO" translatesAutoresizingMaskIntoConstraints="NO" id="hQb-1A-Owa">
-                                        <rect key="frame" x="24" y="178" width="351" height="84"/>
-                                        <constraints>
-                                            <constraint firstAttribute="height" constant="84" id="4vv-6N-LW7"/>
-                                        </constraints>
+                                        <rect key="frame" x="93" y="257.5" width="189.5" height="37"/>
                                         <fontDescription key="fontDescription" type="system" pointSize="31"/>
                                         <nil key="textColor"/>
                                         <nil key="highlightedColor"/>
                                     </label>
-                                    <button opaque="NO" contentMode="scaleToFill" contentHorizontalAlignment="center" contentVerticalAlignment="center" buttonType="roundedRect" lineBreakMode="middleTruncation" translatesAutoresizingMaskIntoConstraints="NO" id="EL3-By-EfQ">
-                                        <rect key="frame" x="95" y="443" width="185" height="70"/>
+                                    <button opaque="NO" contentMode="scaleToFill" contentHorizontalAlignment="center" contentVerticalAlignment="center" buttonType="system" lineBreakMode="middleTruncation" translatesAutoresizingMaskIntoConstraints="NO" id="EL3-By-EfQ">
+                                        <rect key="frame" x="87.5" y="398.5" width="200" height="70"/>
                                         <constraints>
+                                            <constraint firstAttribute="width" constant="200" id="W1g-s4-UT5"/>
                                             <constraint firstAttribute="height" constant="70" id="icQ-0O-eq7"/>
                                         </constraints>
                                         <fontDescription key="fontDescription" type="system" pointSize="28"/>
@@ -152,7 +148,7 @@
                                         </connections>
                                     </button>
                                     <label opaque="NO" userInteractionEnabled="NO" contentMode="left" horizontalHuggingPriority="251" verticalHuggingPriority="251" text="Coupon" textAlignment="center" lineBreakMode="tailTruncation" baselineAdjustment="alignBaselines" adjustsFontSizeToFit="NO" translatesAutoresizingMaskIntoConstraints="NO" id="wfb-0V-K6B">
-                                        <rect key="frame" x="118" y="53" width="163" height="117"/>
+                                        <rect key="frame" x="106" y="100" width="163" height="57.5"/>
                                         <fontDescription key="fontDescription" type="system" pointSize="48"/>
                                         <nil key="textColor"/>
                                         <nil key="highlightedColor"/>
@@ -160,37 +156,32 @@
                                 </subviews>
                                 <color key="backgroundColor" red="1" green="0.70962433775568645" blue="0.12732697910574808" alpha="1" colorSpace="custom" customColorSpace="sRGB"/>
                                 <constraints>
-                                    <constraint firstAttribute="bottom" secondItem="EL3-By-EfQ" secondAttribute="bottom" constant="154" id="IUy-ma-UWg"/>
-                                    <constraint firstAttribute="trailing" secondItem="hQb-1A-Owa" secondAttribute="trailing" id="N39-O6-JZz"/>
+                                    <constraint firstItem="EL3-By-EfQ" firstAttribute="centerY" secondItem="P8x-8I-Y50" secondAttribute="centerY" constant="100" id="DGj-i3-ga3"/>
                                     <constraint firstItem="EL3-By-EfQ" firstAttribute="centerX" secondItem="P8x-8I-Y50" secondAttribute="centerX" id="Wjm-Ve-hnv"/>
-                                    <constraint firstItem="wfb-0V-K6B" firstAttribute="top" secondItem="P8x-8I-Y50" secondAttribute="top" constant="53" id="Wld-ty-6zF"/>
-                                    <constraint firstItem="hQb-1A-Owa" firstAttribute="top" secondItem="wfb-0V-K6B" secondAttribute="bottom" constant="8" symbolic="YES" id="bfS-Ia-5G5"/>
-                                    <constraint firstAttribute="trailing" relation="greaterThanOrEqual" secondItem="wfb-0V-K6B" secondAttribute="trailing" constant="20" symbolic="YES" id="cnn-RZ-BSN"/>
-                                    <constraint firstItem="hQb-1A-Owa" firstAttribute="top" secondItem="P8x-8I-Y50" secondAttribute="top" constant="178" id="ikT-aK-a6i"/>
-                                    <constraint firstItem="hQb-1A-Owa" firstAttribute="leading" secondItem="P8x-8I-Y50" secondAttribute="leading" constant="24" id="ryK-zs-vNC"/>
-                                    <constraint firstItem="wfb-0V-K6B" firstAttribute="leading" secondItem="P8x-8I-Y50" secondAttribute="leading" constant="118" id="t3P-zP-GCa"/>
-                                    <constraint firstItem="EL3-By-EfQ" firstAttribute="leading" secondItem="P8x-8I-Y50" secondAttribute="leading" constant="95" id="uCs-4z-641"/>
+                                    <constraint firstItem="wfb-0V-K6B" firstAttribute="top" secondItem="P8x-8I-Y50" secondAttribute="top" constant="100" id="Wld-ty-6zF"/>
+                                    <constraint firstItem="hQb-1A-Owa" firstAttribute="centerX" secondItem="P8x-8I-Y50" secondAttribute="centerX" id="ayJ-a0-500"/>
+                                    <constraint firstItem="hQb-1A-Owa" firstAttribute="top" secondItem="wfb-0V-K6B" secondAttribute="bottom" constant="100" id="ikT-aK-a6i"/>
+                                    <constraint firstItem="wfb-0V-K6B" firstAttribute="centerX" secondItem="P8x-8I-Y50" secondAttribute="centerX" id="mD1-SO-5Q9"/>
                                 </constraints>
                             </view>
                         </subviews>
                         <color key="backgroundColor" white="1" alpha="1" colorSpace="calibratedWhite"/>
                         <constraints>
                             <constraint firstItem="P8x-8I-Y50" firstAttribute="bottom" secondItem="WeV-sX-2WA" secondAttribute="top" id="3Nn-fD-Q7N"/>
-                            <constraint firstItem="P8x-8I-Y50" firstAttribute="centerX" secondItem="eHj-DU-rky" secondAttribute="centerX" id="8Ow-Cr-o7C"/>
                             <constraint firstItem="P8x-8I-Y50" firstAttribute="trailing" secondItem="ZDA-v7-RgX" secondAttribute="trailing" id="Ah9-m3-EPp"/>
                             <constraint firstItem="WeV-sX-2WA" firstAttribute="top" secondItem="ZDA-v7-RgX" secondAttribute="bottom" id="CrG-tN-JNQ"/>
-                            <constraint firstItem="P8x-8I-Y50" firstAttribute="centerX" secondItem="GuL-M1-dn2" secondAttribute="centerX" id="KBZ-6S-w7y"/>
-                            <constraint firstItem="WeV-sX-2WA" firstAttribute="top" secondItem="eHj-DU-rky" secondAttribute="bottom" constant="207" id="Q0e-fD-Ptx"/>
+                            <constraint firstItem="8CQ-8i-O97" firstAttribute="centerY" secondItem="Pxf-lJ-vhB" secondAttribute="centerY" constant="50" id="DKs-WA-D12"/>
+                            <constraint firstItem="eHj-DU-rky" firstAttribute="top" secondItem="8CQ-8i-O97" secondAttribute="bottom" constant="50" id="Vrz-mA-8W9"/>
                             <constraint firstItem="ZDA-v7-RgX" firstAttribute="leading" secondItem="Pxf-lJ-vhB" secondAttribute="leading" id="WBH-qa-3f2"/>
                             <constraint firstItem="P8x-8I-Y50" firstAttribute="top" secondItem="ZDA-v7-RgX" secondAttribute="top" id="X0h-Jd-EVd"/>
-                            <constraint firstItem="eHj-DU-rky" firstAttribute="leading" secondItem="Pxf-lJ-vhB" secondAttribute="leadingMargin" constant="90" id="Ywc-gQ-W0J"/>
+                            <constraint firstItem="eHj-DU-rky" firstAttribute="leading" secondItem="Pxf-lJ-vhB" secondAttribute="leadingMargin" constant="50" id="Ywc-gQ-W0J"/>
+                            <constraint firstItem="8CQ-8i-O97" firstAttribute="top" secondItem="GuL-M1-dn2" secondAttribute="bottom" constant="20" id="aal-uC-jMK"/>
                             <constraint firstItem="ZDA-v7-RgX" firstAttribute="top" secondItem="Pxf-lJ-vhB" secondAttribute="top" id="bCE-xf-Orz"/>
+                            <constraint firstItem="eHj-DU-rky" firstAttribute="centerX" secondItem="8CQ-8i-O97" secondAttribute="centerX" id="ei3-Y1-ehV"/>
+                            <constraint firstItem="8CQ-8i-O97" firstAttribute="centerX" secondItem="Pxf-lJ-vhB" secondAttribute="centerX" id="iiK-mg-YUm"/>
                             <constraint firstAttribute="trailing" secondItem="ZDA-v7-RgX" secondAttribute="trailing" id="kId-8h-KkR"/>
-                            <constraint firstItem="P8x-8I-Y50" firstAttribute="centerX" secondItem="8CQ-8i-O97" secondAttribute="centerX" id="ne4-QL-Rq1"/>
-                            <constraint firstItem="GuL-M1-dn2" firstAttribute="top" secondItem="LE4-TO-HJE" secondAttribute="bottom" constant="233" id="pdO-VB-4ej"/>
+                            <constraint firstItem="GuL-M1-dn2" firstAttribute="centerX" secondItem="8CQ-8i-O97" secondAttribute="centerX" id="pWR-0s-AtT"/>
                             <constraint firstItem="P8x-8I-Y50" firstAttribute="leading" secondItem="ZDA-v7-RgX" secondAttribute="leading" id="qeC-oH-fUE"/>
-                            <constraint firstItem="eHj-DU-rky" firstAttribute="top" secondItem="GuL-M1-dn2" secondAttribute="bottom" constant="46" id="rl5-eU-WyI"/>
-                            <constraint firstItem="eHj-DU-rky" firstAttribute="top" secondItem="8CQ-8i-O97" secondAttribute="bottom" constant="32" id="x0i-xv-Nvy"/>
                         </constraints>
                     </view>
                     <connections>
@@ -215,21 +206,21 @@
                         <viewControllerLayoutGuide type="bottom" id="ARR-Gc-cn2"/>
                     </layoutGuides>
                     <view key="view" contentMode="scaleToFill" id="yBM-xo-e29">
-                        <rect key="frame" x="0.0" y="0.0" width="375" height="667"/>
+                        <rect key="frame" x="0.0" y="0.0" width="375" height="647"/>
                         <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
                         <subviews>
                             <imageView userInteractionEnabled="NO" contentMode="scaleToFill" horizontalHuggingPriority="251" verticalHuggingPriority="251" restorationIdentifier="ConversionSuccessImageView" image="background_confirmation" translatesAutoresizingMaskIntoConstraints="NO" id="GEt-Bf-Es2">
-                                <rect key="frame" x="0.0" y="0.0" width="375" height="667"/>
+                                <rect key="frame" x="0.0" y="0.0" width="375" height="647"/>
                             </imageView>
                             <textView clipsSubviews="YES" multipleTouchEnabled="YES" contentMode="scaleToFill" editable="NO" text="Conversion event recorded to Optimizely." textAlignment="center" selectable="NO" translatesAutoresizingMaskIntoConstraints="NO" id="CRh-TJ-NCw">
-                                <rect key="frame" x="94" y="139" width="187.5" height="166.5"/>
+                                <rect key="frame" x="94" y="135" width="187.5" height="161.5"/>
                                 <color key="backgroundColor" white="0.0" alpha="0.0" colorSpace="calibratedWhite"/>
                                 <color key="textColor" red="0.019607843137254902" green="0.16862745098039217" blue="0.25490196078431371" alpha="1" colorSpace="calibratedRGB"/>
                                 <fontDescription key="fontDescription" name="ProximaNova-Regular" family="Proxima Nova" pointSize="24"/>
                                 <textInputTraits key="textInputTraits" autocapitalizationType="sentences"/>
                             </textView>
-                            <button opaque="NO" contentMode="scaleToFill" contentHorizontalAlignment="center" contentVerticalAlignment="center" buttonType="roundedRect" lineBreakMode="middleTruncation" translatesAutoresizingMaskIntoConstraints="NO" id="Qje-MN-IfM">
-                                <rect key="frame" x="149.5" y="426" width="76" height="37"/>
+                            <button opaque="NO" contentMode="scaleToFill" contentHorizontalAlignment="center" contentVerticalAlignment="center" buttonType="system" lineBreakMode="middleTruncation" translatesAutoresizingMaskIntoConstraints="NO" id="Qje-MN-IfM">
+                                <rect key="frame" x="149.5" y="413" width="76" height="37"/>
                                 <color key="backgroundColor" red="0.97647058819999999" green="0.039215686270000001" blue="0.054901960780000002" alpha="1" colorSpace="calibratedRGB"/>
                                 <fontDescription key="fontDescription" name="Roboto-Medium" family="Roboto" pointSize="14"/>
                                 <inset key="contentEdgeInsets" minX="20" minY="10" maxX="20" maxY="10"/>
diff --git a/DemoSwiftApp/Samples/SamplesForAPI.swift b/DemoSwiftApp/Samples/SamplesForAPI.swift
index 479f133ea..c0fb8c2d0 100644
--- a/DemoSwiftApp/Samples/SamplesForAPI.swift
+++ b/DemoSwiftApp/Samples/SamplesForAPI.swift
@@ -1,6 +1,6 @@
 //
 /****************************************************************************
- * Copyright 2019-2020, Optimizely, Inc. and contributors                   *
+ * Copyright 2019-2021, Optimizely, Inc. and contributors                   *
  *                                                                          *
  * Licensed under the Apache License, Version 2.0 (the "License");          *
  * you may not use this file except in compliance with the License.         *
@@ -103,6 +103,40 @@ class SamplesForAPI {
         
     }
     
+    // MARK: - OptimizelyUserContext (Decide API)
+    
+    static func checkOptimizelyUserContext(optimizely: OptimizelyClient) {
+        let attributes: [String: Any] = [
+            "location": "NY",
+            "device": "iPhone",
+            "lifetime": 24738388,
+            "is_logged_in": true
+            ]
+        let tags: [String: Any] = [
+            "category": "shoes",
+            "count": 2
+            ]
+
+        let user = optimizely.createUserContext(userId: "user_123", attributes: attributes)
+        
+        let decision = user.decide(key: "show_coupon", options: [.includeReasons])
+        
+        if let variationKey = decision.variationKey {
+            print("[decide] flag decision to variation: \(variationKey)")
+            print("[decide] flag enabled: \(decision.enabled) with variables: \(decision.variables.toMap())")
+            print("[decide] reasons: \(decision.reasons)")
+        } else {
+            print("[decide] error: \(decision.reasons)")
+        }
+        
+        do {
+            try user.trackEvent(eventKey: "my_purchase_event_key", eventTags: tags)
+            print("[track] success")
+        } catch {
+            print("[track] error: \(error)")
+        }
+    }
+    
     // MARK: - OptimizelyConfig
     
     static func checkOptimizelyConfig(optimizely: OptimizelyClient) {
@@ -199,7 +233,7 @@ class SamplesForAPI {
 
     }
     
-    // MARK: - OptimizelyConfig
+    // MARK: - Initializations
 
     static func samplesForInitialization() {
         
diff --git a/OptimizelySwiftSDK.xcodeproj/project.pbxproj b/OptimizelySwiftSDK.xcodeproj/project.pbxproj
index dbc4b73be..ff4512706 100644
--- a/OptimizelySwiftSDK.xcodeproj/project.pbxproj
+++ b/OptimizelySwiftSDK.xcodeproj/project.pbxproj
@@ -24,6 +24,7 @@
 		0B97DDA4249D4A27003DE606 /* SemanticVersion.swift in Sources */ = {isa = PBXBuildFile; fileRef = 0B97DD93249D327F003DE606 /* SemanticVersion.swift */; };
 		0B97DDA5249D4A28003DE606 /* SemanticVersion.swift in Sources */ = {isa = PBXBuildFile; fileRef = 0B97DD93249D327F003DE606 /* SemanticVersion.swift */; };
 		0BAB9B0122567E34000DC388 /* (null) in Sources */ = {isa = PBXBuildFile; };
+		3D8E460B7007B5B46630E046 /* libPods-OptimizelyTests-Common-tvOS.a in Frameworks */ = {isa = PBXBuildFile; fileRef = 1BBBAD25A1207AF13647873E /* libPods-OptimizelyTests-Common-tvOS.a */; };
 		6E12B1CA22C55A250005E9E6 /* optimizely_6372300739_v4.json in Resources */ = {isa = PBXBuildFile; fileRef = 6E75196222C5211100B2B157 /* optimizely_6372300739_v4.json */; };
 		6E12B1CB22C55A250005E9E6 /* feature_rollout_toggle_on.json in Resources */ = {isa = PBXBuildFile; fileRef = 6E75196722C5211100B2B157 /* feature_rollout_toggle_on.json */; };
 		6E12B1CC22C55A250005E9E6 /* feature_rollout_toggle_off.json in Resources */ = {isa = PBXBuildFile; fileRef = 6E75196822C5211100B2B157 /* feature_rollout_toggle_off.json */; };
@@ -430,9 +431,24 @@
 		6E34A647231ED28600BAE302 /* empty_datafile_new_account_id.json in Resources */ = {isa = PBXBuildFile; fileRef = 6E34A63D231ED28600BAE302 /* empty_datafile_new_account_id.json */; };
 		6E34A648231ED28600BAE302 /* empty_datafile_new_account_id.json in Resources */ = {isa = PBXBuildFile; fileRef = 6E34A63D231ED28600BAE302 /* empty_datafile_new_account_id.json */; };
 		6E34A649231ED28600BAE302 /* empty_datafile_new_account_id.json in Resources */ = {isa = PBXBuildFile; fileRef = 6E34A63D231ED28600BAE302 /* empty_datafile_new_account_id.json */; };
+		6E593FB625BB9C5500EC72BC /* OptimizelyClientTests_Decide.swift in Sources */ = {isa = PBXBuildFile; fileRef = 6E593FB425BB9C5500EC72BC /* OptimizelyClientTests_Decide.swift */; };
 		6E5AB69323F6130D007A82B1 /* OptimizelyClientTests_Init_Sync.swift in Sources */ = {isa = PBXBuildFile; fileRef = 6E5AB69123F6130C007A82B1 /* OptimizelyClientTests_Init_Sync.swift */; };
 		6E5AB69423F6130D007A82B1 /* OptimizelyClientTests_Init_Async.swift in Sources */ = {isa = PBXBuildFile; fileRef = 6E5AB69223F6130D007A82B1 /* OptimizelyClientTests_Init_Async.swift */; };
 		6E614DD621E3F38A005982A1 /* Optimizely.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = 6E614DCD21E3F389005982A1 /* Optimizely.framework */; };
+		6E623F02253F9045000617D0 /* DecisionInfo.swift in Sources */ = {isa = PBXBuildFile; fileRef = 6E623F01253F9045000617D0 /* DecisionInfo.swift */; };
+		6E623F03253F9045000617D0 /* DecisionInfo.swift in Sources */ = {isa = PBXBuildFile; fileRef = 6E623F01253F9045000617D0 /* DecisionInfo.swift */; };
+		6E623F04253F9045000617D0 /* DecisionInfo.swift in Sources */ = {isa = PBXBuildFile; fileRef = 6E623F01253F9045000617D0 /* DecisionInfo.swift */; };
+		6E623F05253F9045000617D0 /* DecisionInfo.swift in Sources */ = {isa = PBXBuildFile; fileRef = 6E623F01253F9045000617D0 /* DecisionInfo.swift */; };
+		6E623F06253F9045000617D0 /* DecisionInfo.swift in Sources */ = {isa = PBXBuildFile; fileRef = 6E623F01253F9045000617D0 /* DecisionInfo.swift */; };
+		6E623F07253F9045000617D0 /* DecisionInfo.swift in Sources */ = {isa = PBXBuildFile; fileRef = 6E623F01253F9045000617D0 /* DecisionInfo.swift */; };
+		6E623F08253F9045000617D0 /* DecisionInfo.swift in Sources */ = {isa = PBXBuildFile; fileRef = 6E623F01253F9045000617D0 /* DecisionInfo.swift */; };
+		6E623F09253F9045000617D0 /* DecisionInfo.swift in Sources */ = {isa = PBXBuildFile; fileRef = 6E623F01253F9045000617D0 /* DecisionInfo.swift */; };
+		6E623F0A253F9045000617D0 /* DecisionInfo.swift in Sources */ = {isa = PBXBuildFile; fileRef = 6E623F01253F9045000617D0 /* DecisionInfo.swift */; };
+		6E623F0B253F9045000617D0 /* DecisionInfo.swift in Sources */ = {isa = PBXBuildFile; fileRef = 6E623F01253F9045000617D0 /* DecisionInfo.swift */; };
+		6E623F0C253F9045000617D0 /* DecisionInfo.swift in Sources */ = {isa = PBXBuildFile; fileRef = 6E623F01253F9045000617D0 /* DecisionInfo.swift */; };
+		6E623F0D253F9045000617D0 /* DecisionInfo.swift in Sources */ = {isa = PBXBuildFile; fileRef = 6E623F01253F9045000617D0 /* DecisionInfo.swift */; };
+		6E623F0E253F9045000617D0 /* DecisionInfo.swift in Sources */ = {isa = PBXBuildFile; fileRef = 6E623F01253F9045000617D0 /* DecisionInfo.swift */; };
+		6E623F0F253F9045000617D0 /* DecisionInfo.swift in Sources */ = {isa = PBXBuildFile; fileRef = 6E623F01253F9045000617D0 /* DecisionInfo.swift */; };
 		6E636B912236C91F00AF3CEF /* Optimizely.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = 6EBAEB6C21E3FEF800D13AA9 /* Optimizely.framework */; };
 		6E636BA02236C96700AF3CEF /* Optimizely.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = 6EBAEB6C21E3FEF800D13AA9 /* Optimizely.framework */; };
 		6E6BE00B237F547200FE8274 /* optimizely_config_datafile.json in Resources */ = {isa = PBXBuildFile; fileRef = 6E6BE009237F547200FE8274 /* optimizely_config_datafile.json */; };
@@ -1122,8 +1138,42 @@
 		6E75195D22C520D500B2B157 /* OPTBucketer.swift in Sources */ = {isa = PBXBuildFile; fileRef = 6E7516A522C520D400B2B157 /* OPTBucketer.swift */; };
 		6E75195E22C520D500B2B157 /* OPTBucketer.swift in Sources */ = {isa = PBXBuildFile; fileRef = 6E7516A522C520D400B2B157 /* OPTBucketer.swift */; };
 		6E75195F22C520D500B2B157 /* OPTBucketer.swift in Sources */ = {isa = PBXBuildFile; fileRef = 6E7516A522C520D400B2B157 /* OPTBucketer.swift */; };
+		6E7E9B372523F8BF009E4426 /* OptimizelyUserContextTests_Decide_Reasons.swift in Sources */ = {isa = PBXBuildFile; fileRef = 6E7E9B362523F8BF009E4426 /* OptimizelyUserContextTests_Decide_Reasons.swift */; };
+		6E7E9B382523F8BF009E4426 /* OptimizelyUserContextTests_Decide_Reasons.swift in Sources */ = {isa = PBXBuildFile; fileRef = 6E7E9B362523F8BF009E4426 /* OptimizelyUserContextTests_Decide_Reasons.swift */; };
+		6E7E9B552523F8C6009E4426 /* OptimizelyUserContextTests_Decide_Legacy.swift in Sources */ = {isa = PBXBuildFile; fileRef = 6EB97BCC24C89DFB00068883 /* OptimizelyUserContextTests_Decide_Legacy.swift */; };
+		6E7E9B562523F8C6009E4426 /* OptimizelyUserContextTests_Decide_Legacy.swift in Sources */ = {isa = PBXBuildFile; fileRef = 6EB97BCC24C89DFB00068883 /* OptimizelyUserContextTests_Decide_Legacy.swift */; };
+		6E7E9C2F25240D2E009E4426 /* OptimizelyUserContextTests_Objc.m in Sources */ = {isa = PBXBuildFile; fileRef = 6E86CEB224FF20DE005DAFED /* OptimizelyUserContextTests_Objc.m */; };
+		6E7E9C4C25240D31009E4426 /* OptimizelyUserContextTests_Objc.m in Sources */ = {isa = PBXBuildFile; fileRef = 6E86CEB224FF20DE005DAFED /* OptimizelyUserContextTests_Objc.m */; };
+		6E86CEA224FDC836005DAFED /* OptimizelyUserContext+ObjC.swift in Sources */ = {isa = PBXBuildFile; fileRef = 6E86CEA124FDC836005DAFED /* OptimizelyUserContext+ObjC.swift */; };
+		6E86CEA324FDC836005DAFED /* OptimizelyUserContext+ObjC.swift in Sources */ = {isa = PBXBuildFile; fileRef = 6E86CEA124FDC836005DAFED /* OptimizelyUserContext+ObjC.swift */; };
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+		6E994B3325A3E6EA00999262 /* DecisionResponse.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = DecisionResponse.swift; sourceTree = "<group>"; };
 		6EA0FB1E251A5AEC00EC002D /* bucketer_test3.json */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = text.json; path = bucketer_test3.json; sourceTree = "<group>"; };
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@@ -1654,11 +1793,21 @@
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+		6EB97BCC24C89DFB00068883 /* OptimizelyUserContextTests_Decide_Legacy.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = OptimizelyUserContextTests_Decide_Legacy.swift; sourceTree = "<group>"; };
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+		6EC6DD3024ABF6990017D296 /* OptimizelyClient+Decide.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = "OptimizelyClient+Decide.swift"; sourceTree = "<group>"; };
+		6EC6DD4024ABF89B0017D296 /* OptimizelyUserContext.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = OptimizelyUserContext.swift; sourceTree = "<group>"; };
+		6EC6DD6824AE94820017D296 /* OptimizelyUserContextTests.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = OptimizelyUserContextTests.swift; sourceTree = "<group>"; };
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+		6EF8DE0524B8DA58008B9488 /* decide_datafile.json */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = text.json; path = decide_datafile.json; sourceTree = "<group>"; };
+		6EF8DE0A24BD1BB1008B9488 /* OptimizelyDecision.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = OptimizelyDecision.swift; sourceTree = "<group>"; };
+		6EF8DE0B24BD1BB2008B9488 /* OptimizelyDecideOption.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = OptimizelyDecideOption.swift; sourceTree = "<group>"; };
+		6EF8DE3024BF7D69008B9488 /* DecisionReasons.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = DecisionReasons.swift; sourceTree = "<group>"; };
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+		86CB89E3655313193F1C893D /* Pods-OptimizelyTests-Common-tvOS.debug.xcconfig */ = {isa = PBXFileReference; includeInIndex = 1; lastKnownFileType = text.xcconfig; name = "Pods-OptimizelyTests-Common-tvOS.debug.xcconfig"; path = "Target Support Files/Pods-OptimizelyTests-Common-tvOS/Pods-OptimizelyTests-Common-tvOS.debug.xcconfig"; sourceTree = "<group>"; };
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@@ -1719,6 +1868,7 @@
 			buildActionMask = 2147483647;
 			files = (
 				6EA4250D2218E41600B074B5 /* Optimizely.framework in Frameworks */,
+				3D8E460B7007B5B46630E046 /* libPods-OptimizelyTests-Common-tvOS.a in Frameworks */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 		};
@@ -1735,6 +1885,7 @@
 			buildActionMask = 2147483647;
 			files = (
 				6EA4256F2218E60A00B074B5 /* Optimizely.framework in Frameworks */,
+				7B4A4C11E9A503E68F2FCC69 /* libPods-OptimizelyTests-Common-iOS.a in Frameworks */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 		};
@@ -1785,6 +1936,8 @@
 				6E75165D22C520D400B2B157 /* Sources */,
 				6E75196022C5211100B2B157 /* Tests */,
 				0B7CB0C321AC5FE2007B77E5 /* Products */,
+				5793E12CFD024A5E8594F535 /* Pods */,
+				87DE4DE091B80D1F13BBD781 /* Frameworks */,
 			);
 			sourceTree = "<group>";
 		};
@@ -1809,6 +1962,17 @@
 			name = Products;
 			sourceTree = "<group>";
 		};
+		5793E12CFD024A5E8594F535 /* Pods */ = {
+			isa = PBXGroup;
+			children = (
+				38128F75B12FAAEAA393A591 /* Pods-OptimizelyTests-Common-iOS.debug.xcconfig */,
+				5151BD9C826F9B112DC548AB /* Pods-OptimizelyTests-Common-iOS.release.xcconfig */,
+				86CB89E3655313193F1C893D /* Pods-OptimizelyTests-Common-tvOS.debug.xcconfig */,
+				7630EFE42299849B51CF35AD /* Pods-OptimizelyTests-Common-tvOS.release.xcconfig */,
+			);
+			path = Pods;
+			sourceTree = "<group>";
+		};
 		6E14CD642423F80B00010234 /* OptimizelyTests-Batch-iOS */ = {
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 			children = (
@@ -1830,6 +1994,7 @@
 			isa = PBXGroup;
 			children = (
 				6E75166622C520D400B2B157 /* Optimizely */,
+				6EC6DD3F24ABF8180017D296 /* Optimizely+Decide */,
 				6E75165E22C520D400B2B157 /* Customization */,
 				6E75167C22C520D400B2B157 /* Implementation */,
 				6E75168822C520D400B2B157 /* Data Model */,
@@ -1917,9 +2082,12 @@
 			isa = PBXGroup;
 			children = (
 				6E75167D22C520D400B2B157 /* DefaultDatafileHandler.swift */,
+				6E623F01253F9045000617D0 /* DecisionInfo.swift */,
 				6E75167E22C520D400B2B157 /* DefaultBucketer.swift */,
 				6E75167F22C520D400B2B157 /* DefaultNotificationCenter.swift */,
 				6E75168022C520D400B2B157 /* DefaultDecisionService.swift */,
+				6EF8DE3024BF7D69008B9488 /* DecisionReasons.swift */,
+				6E994B3325A3E6EA00999262 /* DecisionResponse.swift */,
 				6E75168122C520D400B2B157 /* Datastore */,
 				6E75168622C520D400B2B157 /* Events */,
 			);
@@ -2010,7 +2178,6 @@
 				6E75199B22C5211100B2B157 /* OptimizelyTests-DataModel */,
 				6E7519B922C5211100B2B157 /* OptimizelyTests-APIs */,
 				6E7519C722C5211100B2B157 /* OptimizelyTests-Others */,
-				6E7519B522C5211100B2B157 /* OptimizelyTests-Legacy */,
 				6E7519B222C5211100B2B157 /* OptimizelyTests-iOS */,
 				6E75199922C5211100B2B157 /* OptimizelyTests-tvOS */,
 				6E75196122C5211100B2B157 /* TestData */,
@@ -2025,6 +2192,7 @@
 			children = (
 				6E75196322C5211100B2B157 /* benchmark */,
 				6E6BE008237F547200FE8274 /* optmizelyConfig */,
+				6EF8DE0924B8DA5D008B9488 /* decide */,
 				6E75196222C5211100B2B157 /* optimizely_6372300739_v4.json */,
 				6E75196722C5211100B2B157 /* feature_rollout_toggle_on.json */,
 				6E75196822C5211100B2B157 /* feature_rollout_toggle_off.json */,
@@ -2096,6 +2264,11 @@
 				6E75199622C5211100B2B157 /* DatafileHandlerTests.swift */,
 				6E75199722C5211100B2B157 /* BatchEventBuilderTests_EventTags.swift */,
 				6E75199822C5211100B2B157 /* DataStoreTests.swift */,
+				6EC6DD6824AE94820017D296 /* OptimizelyUserContextTests.swift */,
+				6E2D34B8250AD14000A0CDFE /* OptimizelyUserContextTests_Decide.swift */,
+				6E7E9B362523F8BF009E4426 /* OptimizelyUserContextTests_Decide_Reasons.swift */,
+				6EB97BCC24C89DFB00068883 /* OptimizelyUserContextTests_Decide_Legacy.swift */,
+				6E86CEB224FF20DE005DAFED /* OptimizelyUserContextTests_Objc.m */,
 			);
 			path = "OptimizelyTests-Common";
 			sourceTree = "<group>";
@@ -2146,13 +2319,6 @@
 			path = "OptimizelyTests-iOS";
 			sourceTree = "<group>";
 		};
-		6E7519B522C5211100B2B157 /* OptimizelyTests-Legacy */ = {
-			isa = PBXGroup;
-			children = (
-			);
-			path = "OptimizelyTests-Legacy";
-			sourceTree = "<group>";
-		};
 		6E7519B622C5211100B2B157 /* TestUtils */ = {
 			isa = PBXGroup;
 			children = (
@@ -2183,6 +2349,7 @@
 				6E7519C622C5211100B2B157 /* OptimizelyClientTests_ObjcOthers.m */,
 				C78CAF652446DB91009FE876 /* OptimizelyClientTests_OptimizelyJSON.swift */,
 				C78CAF8524485029009FE876 /* OptimizelyClientTests_OptimizelyJSON_Objc.m */,
+				6E593FB425BB9C5500EC72BC /* OptimizelyClientTests_Decide.swift */,
 			);
 			path = "OptimizelyTests-APIs";
 			sourceTree = "<group>";
@@ -2196,6 +2363,35 @@
 			path = "OptimizelyTests-Others";
 			sourceTree = "<group>";
 		};
+		6EC6DD3F24ABF8180017D296 /* Optimizely+Decide */ = {
+			isa = PBXGroup;
+			children = (
+				6EC6DD3024ABF6990017D296 /* OptimizelyClient+Decide.swift */,
+				6EC6DD4024ABF89B0017D296 /* OptimizelyUserContext.swift */,
+				6EF8DE0B24BD1BB2008B9488 /* OptimizelyDecideOption.swift */,
+				6EF8DE0A24BD1BB1008B9488 /* OptimizelyDecision.swift */,
+				6E86CEA124FDC836005DAFED /* OptimizelyUserContext+ObjC.swift */,
+			);
+			path = "Optimizely+Decide";
+			sourceTree = "<group>";
+		};
+		6EF8DE0924B8DA5D008B9488 /* decide */ = {
+			isa = PBXGroup;
+			children = (
+				6EF8DE0524B8DA58008B9488 /* decide_datafile.json */,
+			);
+			path = decide;
+			sourceTree = "<group>";
+		};
+		87DE4DE091B80D1F13BBD781 /* Frameworks */ = {
+			isa = PBXGroup;
+			children = (
+				33BE1D8564FE425132F728C0 /* libPods-OptimizelyTests-Common-iOS.a */,
+				1BBBAD25A1207AF13647873E /* libPods-OptimizelyTests-Common-tvOS.a */,
+			);
+			name = Frameworks;
+			sourceTree = "<group>";
+		};
 /* End PBXGroup section */
 
 /* Begin PBXHeadersBuildPhase section */
@@ -2320,6 +2516,7 @@
 			isa = PBXNativeTarget;
 			buildConfigurationList = 6EA425102218E41600B074B5 /* Build configuration list for PBXNativeTarget "OptimizelyTests-Common-tvOS" */;
 			buildPhases = (
+				33D3D2C9558EA5257B6D8688 /* [CP] Check Pods Manifest.lock */,
 				6EA425042218E41500B074B5 /* Sources */,
 				6EA425052218E41500B074B5 /* Frameworks */,
 				6EA425062218E41500B074B5 /* Resources */,
@@ -2356,6 +2553,7 @@
 			isa = PBXNativeTarget;
 			buildConfigurationList = 6EA425722218E60A00B074B5 /* Build configuration list for PBXNativeTarget "OptimizelyTests-Common-iOS" */;
 			buildPhases = (
+				D2C9B1643DC58DD75D98A52F /* [CP] Check Pods Manifest.lock */,
 				6EA425662218E60A00B074B5 /* Sources */,
 				6EA425672218E60A00B074B5 /* Frameworks */,
 				6EA425682218E60A00B074B5 /* Resources */,
@@ -2485,7 +2683,7 @@
 			isa = PBXProject;
 			attributes = {
 				LastSwiftUpdateCheck = 1130;
-				LastUpgradeCheck = 1000;
+				LastUpgradeCheck = 1200;
 				ORGANIZATIONNAME = Optimizely;
 				TargetAttributes = {
 					6E14CD622423F80B00010234 = {
@@ -2662,6 +2860,7 @@
 				6E12B2C222C55A340005E9E6 /* 100_entities.json in Resources */,
 				6E6BE00B237F547200FE8274 /* optimizely_config_datafile.json in Resources */,
 				6E12B1FA22C55A270005E9E6 /* optimizely_6372300739_v4.json in Resources */,
+				6EF8DE0724B8DA58008B9488 /* decide_datafile.json in Resources */,
 				6E6BE00C237F547200FE8274 /* optimizely_config_expected.json in Resources */,
 				6EA0FB22251A5AEC00EC002D /* bucketer_test3.json in Resources */,
 				6E12B20E22C55A270005E9E6 /* ab_experiments.json in Resources */,
@@ -2740,6 +2939,7 @@
 				6E12B2D122C55A370005E9E6 /* 100_entities.json in Resources */,
 				6E12B27222C55A290005E9E6 /* optimizely_6372300739_v4.json in Resources */,
 				6E12B28622C55A290005E9E6 /* ab_experiments.json in Resources */,
+				6EF8DE0824B8DA58008B9488 /* decide_datafile.json in Resources */,
 				6E12B27E22C55A290005E9E6 /* grouped_experiments.json in Resources */,
 				6E34A62E231ED04900BAE302 /* empty_datafile_new_project_id.json in Resources */,
 				6E12B27B22C55A290005E9E6 /* feature_variables.json in Resources */,
@@ -2816,6 +3016,7 @@
 				6E12B2BF22C55A330005E9E6 /* 100_entities.json in Resources */,
 				6E12B1E222C55A260005E9E6 /* optimizely_6372300739_v4.json in Resources */,
 				6E12B1F622C55A260005E9E6 /* ab_experiments.json in Resources */,
+				6EF8DE0624B8DA58008B9488 /* decide_datafile.json in Resources */,
 				6E12B1EE22C55A260005E9E6 /* grouped_experiments.json in Resources */,
 				6E34A628231ED04900BAE302 /* empty_datafile_new_project_id.json in Resources */,
 				6E12B1EB22C55A260005E9E6 /* feature_variables.json in Resources */,
@@ -3005,6 +3206,53 @@
 		};
 /* End PBXResourcesBuildPhase section */
 
+/* Begin PBXShellScriptBuildPhase section */
+		33D3D2C9558EA5257B6D8688 /* [CP] Check Pods Manifest.lock */ = {
+			isa = PBXShellScriptBuildPhase;
+			buildActionMask = 2147483647;
+			files = (
+			);
+			inputFileListPaths = (
+			);
+			inputPaths = (
+				"${PODS_PODFILE_DIR_PATH}/Podfile.lock",
+				"${PODS_ROOT}/Manifest.lock",
+			);
+			name = "[CP] Check Pods Manifest.lock";
+			outputFileListPaths = (
+			);
+			outputPaths = (
+				"$(DERIVED_FILE_DIR)/Pods-OptimizelyTests-Common-tvOS-checkManifestLockResult.txt",
+			);
+			runOnlyForDeploymentPostprocessing = 0;
+			shellPath = /bin/sh;
+			shellScript = "diff \"${PODS_PODFILE_DIR_PATH}/Podfile.lock\" \"${PODS_ROOT}/Manifest.lock\" > /dev/null\nif [ $? != 0 ] ; then\n    # print error to STDERR\n    echo \"error: The sandbox is not in sync with the Podfile.lock. Run 'pod install' or update your CocoaPods installation.\" >&2\n    exit 1\nfi\n# This output is used by Xcode 'outputs' to avoid re-running this script phase.\necho \"SUCCESS\" > \"${SCRIPT_OUTPUT_FILE_0}\"\n";
+			showEnvVarsInLog = 0;
+		};
+		D2C9B1643DC58DD75D98A52F /* [CP] Check Pods Manifest.lock */ = {
+			isa = PBXShellScriptBuildPhase;
+			buildActionMask = 2147483647;
+			files = (
+			);
+			inputFileListPaths = (
+			);
+			inputPaths = (
+				"${PODS_PODFILE_DIR_PATH}/Podfile.lock",
+				"${PODS_ROOT}/Manifest.lock",
+			);
+			name = "[CP] Check Pods Manifest.lock";
+			outputFileListPaths = (
+			);
+			outputPaths = (
+				"$(DERIVED_FILE_DIR)/Pods-OptimizelyTests-Common-iOS-checkManifestLockResult.txt",
+			);
+			runOnlyForDeploymentPostprocessing = 0;
+			shellPath = /bin/sh;
+			shellScript = "diff \"${PODS_PODFILE_DIR_PATH}/Podfile.lock\" \"${PODS_ROOT}/Manifest.lock\" > /dev/null\nif [ $? != 0 ] ; then\n    # print error to STDERR\n    echo \"error: The sandbox is not in sync with the Podfile.lock. Run 'pod install' or update your CocoaPods installation.\" >&2\n    exit 1\nfi\n# This output is used by Xcode 'outputs' to avoid re-running this script phase.\necho \"SUCCESS\" > \"${SCRIPT_OUTPUT_FILE_0}\"\n";
+			showEnvVarsInLog = 0;
+		};
+/* End PBXShellScriptBuildPhase section */
+
 /* Begin PBXSourcesBuildPhase section */
 		6E14CD5F2423F80B00010234 /* Sources */ = {
 			isa = PBXSourcesBuildPhase;
@@ -3029,9 +3277,11 @@
 				6E14CD962423F9A700010234 /* Variable.swift in Sources */,
 				6E14CD942423F9A700010234 /* FeatureFlag.swift in Sources */,
 				6E14CD9D2423F9C300010234 /* OPTDatafileHandler.swift in Sources */,
+				6EF8DE3624BF7D69008B9488 /* DecisionReasons.swift in Sources */,
 				6E14CD7C2423F98D00010234 /* DefaultDatafileHandler.swift in Sources */,
 				6E14CD9B2423F9C300010234 /* OPTDataStore.swift in Sources */,
 				6E14CD862423F9A100010234 /* EventForDispatch.swift in Sources */,
+				6EC6DD4624ABF89B0017D296 /* OptimizelyUserContext.swift in Sources */,
 				6E14CD762423F97900010234 /* DefaultLogger.swift in Sources */,
 				6E14CD922423F9A700010234 /* Project.swift in Sources */,
 				6E14CDA72423F9C300010234 /* LogMessage.swift in Sources */,
@@ -3042,15 +3292,19 @@
 				C78CAFA824486E0A009FE876 /* OptimizelyJSON+ObjC.swift in Sources */,
 				6E14CD932423F9A700010234 /* Experiment.swift in Sources */,
 				6E14CD982423F9C300010234 /* BackgroundingCallbacks.swift in Sources */,
+				6E623F07253F9045000617D0 /* DecisionInfo.swift in Sources */,
 				C78CAF5C2445AD8D009FE876 /* OptimizelyJSON.swift in Sources */,
 				6E14CDA52423F9C300010234 /* MurmurHash3.swift in Sources */,
+				6E86CEA824FDC847005DAFED /* OptimizelyUserContext+ObjC.swift in Sources */,
 				6E14CD912423F9A700010234 /* TrafficAllocation.swift in Sources */,
 				6E14CD6F2423F93E00010234 /* OptimizelyError.swift in Sources */,
+				6EC6DD3624ABF6990017D296 /* OptimizelyClient+Decide.swift in Sources */,
 				6E14CD752423F97600010234 /* OptimizelyConfig+ObjC.swift in Sources */,
 				6E14CD712423F96800010234 /* OptimizelyClient.swift in Sources */,
 				6E14CD842423F9A100010234 /* BatchEventBuilder.swift in Sources */,
 				6E14CD6E2423F85E00010234 /* EventDispatcherTests_Batch.swift in Sources */,
 				6E14CDA92423F9C300010234 /* Utils.swift in Sources */,
+				6EF8DE1F24BD1BB2008B9488 /* OptimizelyDecideOption.swift in Sources */,
 				6E14CD882423F9A100010234 /* AttributeValue.swift in Sources */,
 				6E14CD822423F9A100010234 /* DataStoreFile.swift in Sources */,
 				6E14CDA42423F9C300010234 /* Notifications.swift in Sources */,
@@ -3072,7 +3326,9 @@
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+				6E623F05253F9045000617D0 /* DecisionInfo.swift in Sources */,
 				C78CAF5A2445AD8D009FE876 /* OptimizelyJSON.swift in Sources */,
 				6E75194A22C520D500B2B157 /* OPTDatafileHandler.swift in Sources */,
+				6E86CEA724FDC846005DAFED /* OptimizelyUserContext+ObjC.swift in Sources */,
 				6E7516CC22C520D400B2B157 /* OPTLogger.swift in Sources */,
 				6E75185A22C520D400B2B157 /* FeatureVariable.swift in Sources */,
+				6EC6DD3424ABF6990017D296 /* OptimizelyClient+Decide.swift in Sources */,
 				6E7517E222C520D400B2B157 /* DefaultDecisionService.swift in Sources */,
 				6E7516D822C520D400B2B157 /* OPTUserProfileService.swift in Sources */,
 				6E75188A22C520D400B2B157 /* Project.swift in Sources */,
 				6E75195622C520D500B2B157 /* OPTBucketer.swift in Sources */,
 				6E7518DE22C520D400B2B157 /* ConditionLeaf.swift in Sources */,
+				6EF8DE1D24BD1BB2008B9488 /* OptimizelyDecideOption.swift in Sources */,
 				6E7518EA22C520D400B2B157 /* ConditionHolder.swift in Sources */,
 				6E75182A22C520D400B2B157 /* BatchEvent.swift in Sources */,
 				6E75191A22C520D500B2B157 /* OPTNotificationCenter.swift in Sources */,
@@ -4057,7 +4418,9 @@
 				6ECB60CC234D5D9C00016D41 /* OptimizelyConfig+ObjC.swift in Sources */,
 				6E75192622C520D500B2B157 /* DataStoreQueueStack.swift in Sources */,
 				6E7517A422C520D400B2B157 /* Array+Extension.swift in Sources */,
+				6EF8DE0F24BD1BB2008B9488 /* OptimizelyDecision.swift in Sources */,
 				6E75186622C520D400B2B157 /* Rollout.swift in Sources */,
+				6E994B3725A3E6EA00999262 /* DecisionResponse.swift in Sources */,
 				6E75183622C520D400B2B157 /* EventForDispatch.swift in Sources */,
 				6E75193E22C520D500B2B157 /* OPTDecisionService.swift in Sources */,
 				6E75178C22C520D400B2B157 /* OptimizelyClient+Extension.swift in Sources */,
@@ -4073,19 +4436,25 @@
 				BD6485402491474500F30986 /* Attribute.swift in Sources */,
 				BD6485412491474500F30986 /* Group.swift in Sources */,
 				BD6485422491474500F30986 /* DefaultBucketer.swift in Sources */,
+				6EF8DE0E24BD1BB2008B9488 /* OptimizelyDecision.swift in Sources */,
+				6EF8DE3324BF7D69008B9488 /* DecisionReasons.swift in Sources */,
 				BD6485432491474500F30986 /* DefaultDatafileHandler.swift in Sources */,
 				BD6485442491474500F30986 /* OPTLogger.swift in Sources */,
 				BD6485452491474500F30986 /* BatchEvent.swift in Sources */,
+				6E623F04253F9045000617D0 /* DecisionInfo.swift in Sources */,
 				BD6485462491474500F30986 /* Event.swift in Sources */,
 				BD6485472491474500F30986 /* OPTEventDispatcher.swift in Sources */,
 				BD6485482491474500F30986 /* DefaultNotificationCenter.swift in Sources */,
+				6E994B3625A3E6EA00999262 /* DecisionResponse.swift in Sources */,
 				BD6485492491474500F30986 /* OPTDecisionService.swift in Sources */,
 				BD64854A2491474500F30986 /* Utils.swift in Sources */,
 				BD64854B2491474500F30986 /* ArrayEventForDispatch+Extension.swift in Sources */,
 				BD64854C2491474500F30986 /* DefaultEventDispatcher.swift in Sources */,
+				6EC6DD3324ABF6990017D296 /* OptimizelyClient+Decide.swift in Sources */,
 				BD64854D2491474500F30986 /* UserAttribute.swift in Sources */,
 				BD64854E2491474500F30986 /* BackgroundingCallbacks.swift in Sources */,
 				BD64854F2491474500F30986 /* DataStoreFile.swift in Sources */,
+				6E86CEA424FDC836005DAFED /* OptimizelyUserContext+ObjC.swift in Sources */,
 				BD6485502491474500F30986 /* OPTBucketer.swift in Sources */,
 				BD6485512491474500F30986 /* OptimizelyResult.swift in Sources */,
 				BD6485522491474500F30986 /* Constants.swift in Sources */,
@@ -4106,6 +4475,7 @@
 				BD6485612491474500F30986 /* Variable.swift in Sources */,
 				BD6485622491474500F30986 /* MurmurHash3.swift in Sources */,
 				BD6485632491474500F30986 /* FeatureVariable.swift in Sources */,
+				6EF8DE1C24BD1BB2008B9488 /* OptimizelyDecideOption.swift in Sources */,
 				BD6485642491474500F30986 /* Rollout.swift in Sources */,
 				BD6485652491474500F30986 /* DataStoreQueueStackImpl+Extension.swift in Sources */,
 				BD6485662491474500F30986 /* OptimizelyJSON.swift in Sources */,
@@ -4115,6 +4485,7 @@
 				BD64856A2491474500F30986 /* Variation.swift in Sources */,
 				BD64856B2491474500F30986 /* ProjectConfig.swift in Sources */,
 				BD64856C2491474500F30986 /* DataStoreQueueStackImpl.swift in Sources */,
+				6EC6DD4324ABF89B0017D296 /* OptimizelyUserContext.swift in Sources */,
 				BD64856D2491474500F30986 /* OptimizelyError.swift in Sources */,
 				BD64856E2491474500F30986 /* EventForDispatch.swift in Sources */,
 				BD64856F2491474500F30986 /* OptimizelyClient+ObjC.swift in Sources */,
@@ -4537,6 +4908,7 @@
 		};
 		6EA425112218E41600B074B5 /* Debug */ = {
 			isa = XCBuildConfiguration;
+			baseConfigurationReference = 86CB89E3655313193F1C893D /* Pods-OptimizelyTests-Common-tvOS.debug.xcconfig */;
 			buildSettings = {
 				CODE_SIGN_STYLE = Automatic;
 				INFOPLIST_FILE = Tests/Info.plist;
@@ -4557,6 +4929,7 @@
 		};
 		6EA425122218E41600B074B5 /* Release */ = {
 			isa = XCBuildConfiguration;
+			baseConfigurationReference = 7630EFE42299849B51CF35AD /* Pods-OptimizelyTests-Common-tvOS.release.xcconfig */;
 			buildSettings = {
 				CODE_SIGN_STYLE = Automatic;
 				INFOPLIST_FILE = Tests/Info.plist;
@@ -4617,6 +4990,7 @@
 		};
 		6EA425732218E60A00B074B5 /* Debug */ = {
 			isa = XCBuildConfiguration;
+			baseConfigurationReference = 38128F75B12FAAEAA393A591 /* Pods-OptimizelyTests-Common-iOS.debug.xcconfig */;
 			buildSettings = {
 				CODE_SIGN_STYLE = Automatic;
 				INFOPLIST_FILE = Tests/Info.plist;
@@ -4635,6 +5009,7 @@
 		};
 		6EA425742218E60A00B074B5 /* Release */ = {
 			isa = XCBuildConfiguration;
+			baseConfigurationReference = 5151BD9C826F9B112DC548AB /* Pods-OptimizelyTests-Common-iOS.release.xcconfig */;
 			buildSettings = {
 				CODE_SIGN_STYLE = Automatic;
 				INFOPLIST_FILE = Tests/Info.plist;
diff --git a/OptimizelySwiftSDK.xcodeproj/xcshareddata/xcschemes/OptimizelySwiftSDK-iOS.xcscheme b/OptimizelySwiftSDK.xcodeproj/xcshareddata/xcschemes/OptimizelySwiftSDK-iOS.xcscheme
index 5427ba0ca..83696298d 100644
--- a/OptimizelySwiftSDK.xcodeproj/xcshareddata/xcschemes/OptimizelySwiftSDK-iOS.xcscheme
+++ b/OptimizelySwiftSDK.xcodeproj/xcshareddata/xcschemes/OptimizelySwiftSDK-iOS.xcscheme
@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <Scheme
-   LastUpgradeVersion = "1130"
+   LastUpgradeVersion = "1200"
    version = "1.3">
    <BuildAction
       parallelizeBuildables = "YES"
diff --git a/OptimizelySwiftSDK.xcodeproj/xcshareddata/xcschemes/OptimizelySwiftSDK-macOS.xcscheme b/OptimizelySwiftSDK.xcodeproj/xcshareddata/xcschemes/OptimizelySwiftSDK-macOS.xcscheme
index 6dfeb90c0..4b31a2240 100644
--- a/OptimizelySwiftSDK.xcodeproj/xcshareddata/xcschemes/OptimizelySwiftSDK-macOS.xcscheme
+++ b/OptimizelySwiftSDK.xcodeproj/xcshareddata/xcschemes/OptimizelySwiftSDK-macOS.xcscheme
@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <Scheme
-   LastUpgradeVersion = "1130"
+   LastUpgradeVersion = "1200"
    version = "1.3">
    <BuildAction
       parallelizeBuildables = "YES"
diff --git a/OptimizelySwiftSDK.xcodeproj/xcshareddata/xcschemes/OptimizelySwiftSDK-tvOS.xcscheme b/OptimizelySwiftSDK.xcodeproj/xcshareddata/xcschemes/OptimizelySwiftSDK-tvOS.xcscheme
index e8b35a9f6..d3233219d 100644
--- a/OptimizelySwiftSDK.xcodeproj/xcshareddata/xcschemes/OptimizelySwiftSDK-tvOS.xcscheme
+++ b/OptimizelySwiftSDK.xcodeproj/xcshareddata/xcschemes/OptimizelySwiftSDK-tvOS.xcscheme
@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <Scheme
-   LastUpgradeVersion = "1130"
+   LastUpgradeVersion = "1200"
    version = "1.3">
    <BuildAction
       parallelizeBuildables = "YES"
diff --git a/Podfile b/Podfile
index cebeceb65..f2ce14f9e 100644
--- a/Podfile
+++ b/Podfile
@@ -13,6 +13,10 @@ def linter_pods
   pod 'SwiftLint'
 end
 
+def common_test_pods
+  pod 'OCMock', '3.7.1'
+end
+
 target 'DemoSwiftiOS' do
   project 'DemoSwiftApp/DemoSwiftApp.xcodeproj/'
   platform :ios, '10.0'
@@ -44,3 +48,26 @@ target 'DemoObjctvOS' do
   use_frameworks!
   #pod 'OptimizelySwiftSDK','3.0.0'
 end
+
+target 'OptimizelyTests-Common-iOS' do
+  project 'OptimizelySwiftSDK.xcodeproj/'
+  platform :ios, '10.0'
+  common_test_pods
+end
+
+target 'OptimizelyTests-Common-tvOS' do
+  project 'OptimizelySwiftSDK.xcodeproj/'
+  platform :tvos, '10.0'
+  common_test_pods
+end
+
+# Disable Code Coverage for Pods projects
+post_install do |installer_representation|
+    installer_representation.pods_project.targets.each do |target|
+        target.build_configurations.each do |config|
+            config.build_settings['CLANG_ENABLE_CODE_COVERAGE'] = 'NO'
+        end
+    end
+end
+
+
diff --git a/Podfile.lock b/Podfile.lock
index a84ff107b..95e54dbe7 100644
--- a/Podfile.lock
+++ b/Podfile.lock
@@ -1,16 +1,20 @@
 PODS:
-  - SwiftLint (0.38.2)
+  - OCMock (3.7.1)
+  - SwiftLint (0.40.3)
 
 DEPENDENCIES:
+  - OCMock (= 3.7.1)
   - SwiftLint
 
 SPEC REPOS:
   trunk:
+    - OCMock
     - SwiftLint
 
 SPEC CHECKSUMS:
-  SwiftLint: 8f5d2f903e1c9bcbc832fd16771e80a263ac6cbb
+  OCMock: 75fbeaa46a9b11f8c182bbb1d1f7e9a35ccc9955
+  SwiftLint: dfd554ff0dff17288ee574814ccdd5cea85d76f7
 
-PODFILE CHECKSUM: 159491f53ea704c30be049e048d854a49f9b7433
+PODFILE CHECKSUM: 0195918f4c7b47425ae284153b642617e2ef6781
 
-COCOAPODS: 1.9.1
+COCOAPODS: 1.9.3
diff --git a/Sources/Customization/DefaultUserProfileService.swift b/Sources/Customization/DefaultUserProfileService.swift
index 2bfd049e0..439dd7a79 100644
--- a/Sources/Customization/DefaultUserProfileService.swift
+++ b/Sources/Customization/DefaultUserProfileService.swift
@@ -1,5 +1,5 @@
 /****************************************************************************
-* Copyright 2019, Optimizely, Inc. and contributors                        *
+* Copyright 2019,2021, Optimizely, Inc. and contributors                   *
 *                                                                          *
 * Licensed under the Apache License, Version 2.0 (the "License");          *
 * you may not use this file except in compliance with the License.         *
@@ -13,7 +13,6 @@
 * See the License for the specific language governing permissions and      *
 * limitations under the License.                                           *
 ***************************************************************************/
-
 import Foundation
 
 //{
diff --git a/Sources/Data Model/Audience/AttributeValue.swift b/Sources/Data Model/Audience/AttributeValue.swift
index 710058e67..96b72be69 100644
--- a/Sources/Data Model/Audience/AttributeValue.swift	
+++ b/Sources/Data Model/Audience/AttributeValue.swift	
@@ -1,5 +1,5 @@
 /****************************************************************************
-* Copyright 2019-2020, Optimizely, Inc. and contributors                   *
+* Copyright 2019-2021, Optimizely, Inc. and contributors                   *
 *                                                                          *
 * Licensed under the Apache License, Version 2.0 (the "License");          *
 * you may not use this file except in compliance with the License.         *
@@ -266,7 +266,7 @@ extension AttributeValue {
     }
     
     func isValidForExactMatcher() -> Bool {
-        switch (self) {
+        switch self {
         case (.string): return true
         case (.int): return true
         case (.double): return true
diff --git a/Sources/Data Model/Audience/SemanticVersion.swift b/Sources/Data Model/Audience/SemanticVersion.swift
index c8db063c8..bb12ca4d6 100644
--- a/Sources/Data Model/Audience/SemanticVersion.swift	
+++ b/Sources/Data Model/Audience/SemanticVersion.swift	
@@ -28,46 +28,44 @@ extension SemanticVersion {
             return 0
           }
         
-
         let targetedVersionParts = try targetedVersion.splitSemanticVersion()
         let versionParts = try self.splitSemanticVersion()
 
         // Up to the precision of targetedVersion, expect version to match exactly.
-        for (idx, _) in targetedVersionParts.enumerated() {
+        for idx in targetedVersionParts.indices {
             if versionParts.count <= idx {
                 // even if they are equal at this point. if the target is a prerelease then it must be greater than the pre release.
                 return targetedVersion.isPreRelease ?  1 : -1
             } else if !versionParts[idx].isNumber {
                 //Compare strings
                 if versionParts[idx] < targetedVersionParts[idx] {
-                    return targetedVersion.isPreRelease && !self.isPreRelease ? 1: -1;
-                }
-                else if versionParts[idx] > targetedVersionParts[idx] {
-                    return !targetedVersion.isPreRelease && self.isPreRelease ? -1: 1;
+                    return targetedVersion.isPreRelease && !self.isPreRelease ? 1 : -1
+                } else if versionParts[idx] > targetedVersionParts[idx] {
+                    return !targetedVersion.isPreRelease && self.isPreRelease ? -1 : 1
                 }
                 
-            } else if let part = Int(versionParts[idx]), let target = Int(targetedVersionParts[idx]){
-                if (part < target) {
-                  return -1;
+            } else if let part = Int(versionParts[idx]), let target = Int(targetedVersionParts[idx]) {
+                if part < target {
+                  return -1
                 } else if part > target {
-                  return 1;
+                  return 1
                 }
             } else {
-                return -1;
+                return -1
             }
         }
         
         if self.isPreRelease && !targetedVersion.isPreRelease {
-            return -1;
+            return -1
         }
     
-        return 0;
+        return 0
     }
     
     func splitSemanticVersion() throws -> [Substring] {
-        var targetParts:[Substring]?
+        var targetParts: [Substring]?
         var targetPrefix = self
-        var targetSuffix:ArraySlice<Substring>?
+        var targetSuffix: ArraySlice<Substring>?
         
         if hasWhiteSpace {
             throw OptimizelyError.attributeFormatInvalid
@@ -114,10 +112,10 @@ extension SemanticVersion {
         return firstIndex(of: "+")?.utf16Offset(in: self) ?? Int.max < firstIndex(of: "-")?.utf16Offset(in: self) ?? Int.max
     }
     
-    var buildSeperator:Character {
+    var buildSeperator: Character {
         return "+"
     }
-    var preReleaseSeperator:Character {
+    var preReleaseSeperator: Character {
         return "-"
     }
 }
diff --git a/Sources/Data Model/Audience/UserAttribute.swift b/Sources/Data Model/Audience/UserAttribute.swift
index 407a31eea..7f0406613 100644
--- a/Sources/Data Model/Audience/UserAttribute.swift	
+++ b/Sources/Data Model/Audience/UserAttribute.swift	
@@ -174,7 +174,7 @@ extension UserAttribute {
         }
     }
     
-    private func targetAsAttributeValue(value:Any?, attribute:AttributeValue?, nameFinal:String) throws -> AttributeValue {
+    private func targetAsAttributeValue(value: Any?, attribute: AttributeValue?, nameFinal: String) throws -> AttributeValue {
         guard let targetValue = AttributeValue(value: value), targetValue.isComparable(with: attribute!) else {
             throw OptimizelyError.evaluateAttributeInvalidCondition("attribute value \(nameFinal) invalid type")
          }
diff --git a/Sources/Data Model/Project.swift b/Sources/Data Model/Project.swift
index 3355834d2..c52a033e4 100644
--- a/Sources/Data Model/Project.swift	
+++ b/Sources/Data Model/Project.swift	
@@ -1,5 +1,5 @@
 /****************************************************************************
- * Copyright 2019-2020, Optimizely, Inc. and contributors                   *
+ * Copyright 2019-2021, Optimizely, Inc. and contributors                   *
  *                                                                          *
  * Licensed under the Apache License, Version 2.0 (the "License");          *
  * you may not use this file except in compliance with the License.         *
@@ -57,9 +57,12 @@ struct Project: Codable, Equatable {
     }
     
     // Required since logger is not equatable
-    static func ==(lhs: Project, rhs: Project) -> Bool {
+    static func == (lhs: Project, rhs: Project) -> Bool {
         return lhs.version == rhs.version && lhs.projectId == rhs.projectId && lhs.experiments == rhs.experiments &&
-            lhs.audiences == rhs.audiences && lhs.groups == rhs.groups && lhs.attributes == rhs.attributes && lhs.accountId == rhs.accountId && lhs.events == rhs.events && lhs.revision == rhs.revision && lhs.anonymizeIP == rhs.anonymizeIP && lhs.rollouts == rhs.rollouts && lhs.typedAudiences == rhs.typedAudiences && lhs.featureFlags == rhs.featureFlags && lhs.botFiltering == rhs.botFiltering && lhs.sendFlagDecisions == rhs.sendFlagDecisions
+            lhs.audiences == rhs.audiences && lhs.groups == rhs.groups && lhs.attributes == rhs.attributes &&
+            lhs.accountId == rhs.accountId && lhs.events == rhs.events && lhs.revision == rhs.revision &&
+            lhs.anonymizeIP == rhs.anonymizeIP && lhs.rollouts == rhs.rollouts && lhs.typedAudiences == rhs.typedAudiences &&
+            lhs.featureFlags == rhs.featureFlags && lhs.botFiltering == rhs.botFiltering && lhs.sendFlagDecisions == rhs.sendFlagDecisions
     }
 }
 
diff --git a/Sources/Data Model/ProjectConfig.swift b/Sources/Data Model/ProjectConfig.swift
index a2325169f..f0fdf7e5e 100644
--- a/Sources/Data Model/ProjectConfig.swift	
+++ b/Sources/Data Model/ProjectConfig.swift	
@@ -1,5 +1,5 @@
 /****************************************************************************
- * Copyright 2019-2020, Optimizely, Inc. and contributors                   *
+ * Copyright 2019-2021, Optimizely, Inc. and contributors                   *
  *                                                                          *
  * Licensed under the Apache License, Version 2.0 (the "License");          *
  * you may not use this file except in compliance with the License.         *
@@ -74,6 +74,10 @@ class ProjectConfig {
         return map
     }()
     
+    lazy var featureFlagKeys: [String] = {
+        return project.featureFlags.map { $0.key }
+    }()
+
     lazy var rolloutIdMap: [String: Rollout] = {
         var map = [String: Rollout]()
         project.rollouts.forEach { map[$0.id] = $0 }
@@ -278,23 +282,31 @@ extension ProjectConfig {
     /**
      * Get forced variation for a given experiment key and user id.
      */
-    func getForcedVariation(experimentKey: String, userId: String) -> Variation? {
+    func getForcedVariation(experimentKey: String, userId: String) -> DecisionResponse<Variation> {
+        let reasons = DecisionReasons()
+        
         guard let experiment = getExperiment(key: experimentKey) else {
-            return nil
+            return DecisionResponse(result: nil, reasons: reasons)
         }
         
         if let id = getWhitelistedVariationId(userId: userId, experimentId: experiment.id) {
             if let variation = experiment.getVariation(id: id) {
-                logger.d(.userHasForcedVariation(userId, experiment.key, variation.key))
-                return variation
+                let info = LogMessage.userHasForcedVariation(userId, experiment.key, variation.key)
+                logger.d(info)
+                reasons.addInfo(info)
+
+                return DecisionResponse(result: variation, reasons: reasons)
             }
             
-            logger.d(.userHasForcedVariationButInvalid(userId, experiment.key))
-            return nil
+            let info = LogMessage.userHasForcedVariationButInvalid(userId, experiment.key)
+            logger.d(info)
+            reasons.addInfo(info)
+
+            return DecisionResponse(result: nil, reasons: reasons)
         }
         
         logger.d(.userHasNoForcedVariationForExperiment(userId, experiment.key))
-        return nil
+        return DecisionResponse(result: nil, reasons: reasons)
     }
     
     /**
diff --git a/Sources/Extensions/OptimizelyClient+Extension.swift b/Sources/Extensions/OptimizelyClient+Extension.swift
index 0a0ba04fe..39d62cdc0 100644
--- a/Sources/Extensions/OptimizelyClient+Extension.swift
+++ b/Sources/Extensions/OptimizelyClient+Extension.swift
@@ -1,5 +1,5 @@
 /****************************************************************************
-* Copyright 2019-2020, Optimizely, Inc. and contributors                   *
+* Copyright 2019-2021, Optimizely, Inc. and contributors                   *
 *                                                                          *
 * Licensed under the Apache License, Version 2.0 (the "License");          *
 * you may not use this file except in compliance with the License.         *
@@ -56,15 +56,22 @@ extension OptimizelyClient {
     ///         The recommended value is 10 * 60 secs (you can also set this to nil to use the recommended value).
     ///         Set this to 0 to disable periodic downloading.
     ///   - defaultLogLevel: default log level (optional. default = .info)
+    ///   - defaultDecisionOptions: default decision optiopns (optional)
     public convenience init(sdkKey: String,
                             logger: OPTLogger? = nil,
                             eventDispatcher: OPTEventDispatcher? = nil,
                             userProfileService: OPTUserProfileService? = nil,
                             periodicDownloadInterval: Int?,
-                            defaultLogLevel: OptimizelyLogLevel? = nil) {
+                            defaultLogLevel: OptimizelyLogLevel? = nil,
+                            defaultDecideOptions: [OptimizelyDecideOption]? = nil) {
         let interval = periodicDownloadInterval ?? 10 * 60
         
-        self.init(sdkKey: sdkKey, logger: logger, eventDispatcher: eventDispatcher, userProfileService: userProfileService, defaultLogLevel: defaultLogLevel)
+        self.init(sdkKey: sdkKey,
+                  logger: logger,
+                  eventDispatcher: eventDispatcher,
+                  userProfileService: userProfileService,
+                  defaultLogLevel: defaultLogLevel,
+                  defaultDecideOptions: defaultDecideOptions)
         
         if let handler = datafileHandler as? DefaultDatafileHandler, interval > 0 {
             handler.setTimer(sdkKey: sdkKey, interval: interval)
diff --git a/Sources/Implementation/Datastore/DataStoreFile.swift b/Sources/Implementation/Datastore/DataStoreFile.swift
index 61b241c17..666377532 100644
--- a/Sources/Implementation/Datastore/DataStoreFile.swift
+++ b/Sources/Implementation/Datastore/DataStoreFile.swift
@@ -64,8 +64,7 @@ public class DataStoreFile<T>: OPTDataStore where T: Codable {
                     if isArray() {
                         let item = try JSONDecoder().decode(T.self, from: contents)
                         returnItem = item
-                    }
-                    else {
+                    } else {
                         let item = try JSONDecoder().decode([T].self, from: contents)
                         returnItem = item.first
                     }
@@ -97,15 +96,16 @@ public class DataStoreFile<T>: OPTDataStore where T: Codable {
             do {
                 if let value = value as? T {
                     var data: Data?
+                    
                     // don't bother to convert... otherwise, do
                     if let value = value as? Data {
                         data = value
                     } else if (value as? NSArray) != nil {
                         data = try JSONEncoder().encode(value)
-                    }
-                    else {
+                    } else {
                         data = try JSONEncoder().encode([value])
                     }
+                    
                     if let data = data {
                         try data.write(to: self.url, options: .atomic)
                     }
diff --git a/Sources/Implementation/DecisionInfo.swift b/Sources/Implementation/DecisionInfo.swift
new file mode 100644
index 000000000..40ae0d703
--- /dev/null
+++ b/Sources/Implementation/DecisionInfo.swift
@@ -0,0 +1,150 @@
+//
+/****************************************************************************
+* Copyright 2021, Optimizely, Inc. and contributors                        *
+*                                                                          *
+* Licensed under the Apache License, Version 2.0 (the "License");          *
+* you may not use this file except in compliance with the License.         *
+* You may obtain a copy of the License at                                  *
+*                                                                          *
+*    http://www.apache.org/licenses/LICENSE-2.0                            *
+*                                                                          *
+* Unless required by applicable law or agreed to in writing, software      *
+* distributed under the License is distributed on an "AS IS" BASIS,        *
+* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. *
+* See the License for the specific language governing permissions and      *
+* limitations under the License.                                           *
+***************************************************************************/
+    
+import Foundation
+
+struct DecisionInfo {
+    
+    /// The decision type.
+    let decisionType: Constants.DecisionType
+    
+    /// The experiment that the decision variation belongs to.
+    var experiment: Experiment?
+    
+    /// The variation selected by the decision.
+    var variation: Variation?
+    
+    // The source of the decision
+    var source: String?
+    
+    /// The flag for which the decision has been made.
+    var feature: FeatureFlag?
+    
+    /// The boolean value indicating the flag is enabled or not.
+    var featureEnabled: Bool?
+    
+    /// The key of the requested flag variable.
+    var variableKey: String?
+    
+    /// The type of the requested flag variable.
+    var variableType: String?
+    
+    /// The value of the requested flag variable.
+    var variableValue: Any?
+    
+    /// The map of all the requested flag variable values.
+    var variableValues: [String: Any]?
+    
+    /// The ruleKey for the decision (for .flag type only).
+    var ruleKey: String?
+    
+    /// The array of decision reason messages (for .flag type only).
+    var reasons: [String]?
+    
+    /// The boolean value indicating an decision event has been sent for the decision (for .flag type only).
+    var decisionEventDispatched: Bool
+    
+    init(decisionType: Constants.DecisionType,
+         experiment: Experiment? = nil,
+         variation: Variation? = nil,
+         source: String? = nil,
+         feature: FeatureFlag? = nil,
+         featureEnabled: Bool? = nil,
+         variableKey: String? = nil,
+         variableType: String? = nil,
+         variableValue: Any? = nil,
+         variableValues: [String: Any]? = nil,
+         ruleKey: String? = nil,
+         reasons: [String]? = nil,
+         decisionEventDispatched: Bool = false) {
+        
+        self.decisionType = decisionType
+        self.experiment = experiment
+        self.variation = variation
+        self.source = source
+        self.feature = feature
+        self.featureEnabled = featureEnabled
+        self.variableKey = variableKey
+        self.variableType = variableType
+        self.variableValue = variableValue
+        self.variableValues = variableValues
+        self.ruleKey = ruleKey
+        self.reasons = reasons
+        self.decisionEventDispatched = decisionEventDispatched
+    }
+    
+    var toMap: [String: Any] {
+        var decisionInfo = [String: Any]()
+        
+        switch decisionType {
+        case .featureTest, .abTest:
+            guard let experiment = experiment else { return decisionInfo }
+            
+            decisionInfo[Constants.ExperimentDecisionInfoKeys.experiment] = experiment.key
+            decisionInfo[Constants.ExperimentDecisionInfoKeys.variation] = variation?.key ?? NSNull()
+            
+        case .feature, .featureVariable, .allFeatureVariables:
+            guard let feature = feature, let featureEnabled = featureEnabled else { return decisionInfo }
+            
+            decisionInfo[Constants.DecisionInfoKeys.feature] = feature.key
+            decisionInfo[Constants.DecisionInfoKeys.featureEnabled] = featureEnabled
+            
+            let decisionSource: Constants.DecisionSource = experiment != nil ? .featureTest : .rollout
+            decisionInfo[Constants.DecisionInfoKeys.source] = source ?? decisionSource.rawValue
+            
+            var sourceInfo = [String: Any]()
+            if let experiment = experiment, let variation = variation {
+                sourceInfo[Constants.ExperimentDecisionInfoKeys.experiment] = experiment.key
+                sourceInfo[Constants.ExperimentDecisionInfoKeys.variation] = variation.key
+            }
+            decisionInfo[Constants.DecisionInfoKeys.sourceInfo] = sourceInfo
+            
+            // featureVariable
+            
+            if decisionType == .featureVariable {
+                guard let variableKey = variableKey, let variableType = variableType, let variableValue = variableValue else {
+                    return decisionInfo
+                }
+                
+                decisionInfo[Constants.DecisionInfoKeys.variable] = variableKey
+                decisionInfo[Constants.DecisionInfoKeys.variableType] = variableType
+                decisionInfo[Constants.DecisionInfoKeys.variableValue] = variableValue
+            } else if  decisionType == .allFeatureVariables {
+                guard let variableValues = variableValues else {
+                    return decisionInfo
+                }
+                decisionInfo[Constants.DecisionInfoKeys.variableValues] = variableValues
+            }
+            
+        // Decide-APIs
+            
+        case .flag:
+            guard let flagKey = feature?.key, let enabled = featureEnabled else { return decisionInfo }
+            
+            decisionInfo[Constants.DecisionInfoKeys.flagKey] = flagKey
+            decisionInfo[Constants.DecisionInfoKeys.enabled] = enabled
+            decisionInfo[Constants.DecisionInfoKeys.variables] = variableValues
+            decisionInfo[Constants.DecisionInfoKeys.variationKey] = variation?.key
+            decisionInfo[Constants.DecisionInfoKeys.ruleKey] = ruleKey
+            decisionInfo[Constants.DecisionInfoKeys.reasons] = reasons
+            decisionInfo[Constants.DecisionInfoKeys.decisionEventDispatched] = decisionEventDispatched
+        }
+        
+        return decisionInfo
+    }
+
+}
diff --git a/Sources/Implementation/DecisionReasons.swift b/Sources/Implementation/DecisionReasons.swift
new file mode 100644
index 000000000..ddafd418f
--- /dev/null
+++ b/Sources/Implementation/DecisionReasons.swift
@@ -0,0 +1,55 @@
+/****************************************************************************
+* Copyright 2021, Optimizely, Inc. and contributors                        *
+*                                                                          *
+* Licensed under the Apache License, Version 2.0 (the "License");          *
+* you may not use this file except in compliance with the License.         *
+* You may obtain a copy of the License at                                  *
+*                                                                          *
+*    http://www.apache.org/licenses/LICENSE-2.0                            *
+*                                                                          *
+* Unless required by applicable law or agreed to in writing, software      *
+* distributed under the License is distributed on an "AS IS" BASIS,        *
+* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. *
+* See the License for the specific language governing permissions and      *
+* limitations under the License.                                           *
+***************************************************************************/
+
+import Foundation
+
+protocol ReasonProtocol {
+    var reason: String { get }
+}
+
+class DecisionReasons {
+    var errors: [ReasonProtocol]
+    var infos: [ReasonProtocol]?
+    
+    init(includeInfos: Bool = true) {
+        errors = []
+        if includeInfos {
+            infos = []
+        }
+    }
+
+    convenience init(options: [OptimizelyDecideOption]?) {
+        // include infos if options is not provided (default)
+        self.init(includeInfos: options?.contains(.includeReasons) ?? true)
+    }
+    
+    func addError(_ error: ReasonProtocol) {
+        errors.append(error)
+    }
+    
+    func addInfo(_ info: ReasonProtocol) {
+        infos?.append(info)
+    }
+    
+    func merge(_ reasons: DecisionReasons) {
+        errors.append(contentsOf: reasons.errors)
+        infos?.append(contentsOf: reasons.infos ?? [])
+    }
+    
+    func toReport() -> [String] {
+        return (errors + (infos ?? [])).map { $0.reason }
+    }
+}
diff --git a/Sources/Implementation/DecisionResponse.swift b/Sources/Implementation/DecisionResponse.swift
new file mode 100644
index 000000000..8cc03863a
--- /dev/null
+++ b/Sources/Implementation/DecisionResponse.swift
@@ -0,0 +1,35 @@
+/***************************************************************************
+* Copyright 2021, Optimizely, Inc. and contributors                        *
+*                                                                          *
+* Licensed under the Apache License, Version 2.0 (the "License");          *
+* you may not use this file except in compliance with the License.         *
+* You may obtain a copy of the License at                                  *
+*                                                                          *
+*    http://www.apache.org/licenses/LICENSE-2.0                            *
+*                                                                          *
+* Unless required by applicable law or agreed to in writing, software      *
+* distributed under the License is distributed on an "AS IS" BASIS,        *
+* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. *
+* See the License for the specific language governing permissions and      *
+* limitations under the License.                                           *
+***************************************************************************/
+
+import Foundation
+
+class DecisionResponse<T> {
+    var result: T?
+    var reasons: DecisionReasons
+    
+    init(result: T?, reasons: DecisionReasons) {
+        self.result = result
+        self.reasons = reasons
+    }
+    
+    static func responseNoReasons(result: T?) -> DecisionResponse {
+        return DecisionResponse(result: result, reasons: DecisionReasons(includeInfos: false))
+    }
+    
+    static func nilNoReasons() -> DecisionResponse {
+        return DecisionResponse(result: nil, reasons: DecisionReasons(includeInfos: false))
+    }
+}
diff --git a/Sources/Implementation/DefaultBucketer.swift b/Sources/Implementation/DefaultBucketer.swift
index 99dd148a7..2b17332d7 100644
--- a/Sources/Implementation/DefaultBucketer.swift
+++ b/Sources/Implementation/DefaultBucketer.swift
@@ -1,18 +1,18 @@
 /****************************************************************************
-* Copyright 2019-2020, Optimizely, Inc. and contributors                   *
-*                                                                          *
-* Licensed under the Apache License, Version 2.0 (the "License");          *
-* you may not use this file except in compliance with the License.         *
-* You may obtain a copy of the License at                                  *
-*                                                                          *
-*    http://www.apache.org/licenses/LICENSE-2.0                            *
-*                                                                          *
-* Unless required by applicable law or agreed to in writing, software      *
-* distributed under the License is distributed on an "AS IS" BASIS,        *
-* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. *
-* See the License for the specific language governing permissions and      *
-* limitations under the License.                                           *
-***************************************************************************/
+ * Copyright 2019-2021, Optimizely, Inc. and contributors                   *
+ *                                                                          *
+ * Licensed under the Apache License, Version 2.0 (the "License");          *
+ * you may not use this file except in compliance with the License.         *
+ * You may obtain a copy of the License at                                  *
+ *                                                                          *
+ *    http://www.apache.org/licenses/LICENSE-2.0                            *
+ *                                                                          *
+ * Unless required by applicable law or agreed to in writing, software      *
+ * distributed under the License is distributed on an "AS IS" BASIS,        *
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. *
+ * See the License for the specific language governing permissions and      *
+ * limitations under the License.                                           *
+ ***************************************************************************/
 
 import Foundation
 
@@ -27,8 +27,12 @@ class DefaultBucketer: OPTBucketer {
     init() {
         MAX_HASH_VALUE = MAX_HASH_SEED << 32
     }
-
-    func bucketExperiment(config: ProjectConfig, experiment: Experiment, bucketingId: String) -> Variation? {
+    
+    func bucketExperiment(config: ProjectConfig,
+                          experiment: Experiment,
+                          bucketingId: String) -> DecisionResponse<Variation> {
+        let reasons = DecisionReasons()
+        
         var mutexAllowed = true
         
         // check for mutex
@@ -40,82 +44,110 @@ class DefaultBucketer: OPTBucketer {
             case .overlapping:
                 break
             case .random:
-                let mutexExperiment = bucketToExperiment(config: config, group: group, bucketingId: bucketingId)
-                if let mutexExperiment = mutexExperiment {
+                let decisionResponse = bucketToExperiment(config: config,
+                                                          group: group,
+                                                          bucketingId: bucketingId)
+                reasons.merge(decisionResponse.reasons)
+                if let mutexExperiment = decisionResponse.result {
                     if mutexExperiment.id == experiment.id {
                         mutexAllowed = true
-                        logger.i(.userBucketedIntoExperimentInGroup(bucketingId, experiment.key, group.id))
+                        
+                        let info = LogMessage.userBucketedIntoExperimentInGroup(bucketingId, experiment.key, group.id)
+                        logger.i(info)
+                        reasons.addInfo(info)
                     } else {
                         mutexAllowed = false
-                        logger.i(.userNotBucketedIntoExperimentInGroup(bucketingId, experiment.key, group.id))
+                        
+                        let info = LogMessage.userNotBucketedIntoExperimentInGroup(bucketingId, experiment.key, group.id)
+                        logger.i(info)
+                        reasons.addInfo(info)
                     }
                 } else {
                     mutexAllowed = false
-                    logger.i(.userNotBucketedIntoAnyExperimentInGroup(bucketingId, group.id))
+                    
+                    let info = LogMessage.userNotBucketedIntoAnyExperimentInGroup(bucketingId, group.id)
+                    logger.i(info)
+                    reasons.addInfo(info)
                 }
             }
         }
         
-        if !mutexAllowed { return nil }
+        if !mutexAllowed { return DecisionResponse(result: nil, reasons: reasons) }
         
         // bucket to variation only if experiment passes Mutex check
-
-        if let variation = bucketToVariation(experiment: experiment, bucketingId: bucketingId) {
-            return variation
-        } else {
-            return nil
-        }
+        
+        let decisionResponse = bucketToVariation(experiment: experiment,
+                                                 bucketingId: bucketingId)
+        reasons.merge(decisionResponse.reasons)
+        let variation = decisionResponse.result
+        return DecisionResponse(result: variation, reasons: reasons)
     }
     
-    func bucketToExperiment(config: ProjectConfig, group: Group, bucketingId: String) -> Experiment? {
+    func bucketToExperiment(config: ProjectConfig,
+                            group: Group,
+                            bucketingId: String) -> DecisionResponse<Experiment> {
+        let reasons = DecisionReasons()
+        
         let hashId = makeHashIdFromBucketingId(bucketingId: bucketingId, entityId: group.id)
         let bucketValue = self.generateBucketValue(bucketingId: hashId)
-        logger.d(.userAssignedToBucketValue(bucketValue, bucketingId))
+        
+        let info = LogMessage.userAssignedToBucketValue(bucketValue, bucketingId)
+        logger.d(info)
+        reasons.addInfo(info)
         
         if group.trafficAllocation.count == 0 {
-            logger.e(.groupHasNoTrafficAllocation(group.id))
-            return nil
+            let info = OptimizelyError.groupHasNoTrafficAllocation(group.id)
+            logger.e(info)
+            reasons.addInfo(info)
+            return DecisionResponse(result: nil, reasons: reasons)
         }
         
         if let experimentId = allocateTraffic(trafficAllocation: group.trafficAllocation, bucketValue: bucketValue) {
             if let experiment = config.getExperiment(id: experimentId) {
-                return experiment
+                return DecisionResponse(result: experiment, reasons: reasons)
             } else {
-                logger.e(.userBucketedIntoInvalidExperiment(experimentId))
-                return nil
+                let info = LogMessage.userBucketedIntoInvalidExperiment(experimentId)
+                logger.e(info)
+                reasons.addInfo(info)
+                return DecisionResponse(result: nil, reasons: reasons)
             }
         }
         
-        return nil
+        return DecisionResponse(result: nil, reasons: reasons)
     }
-
-    func bucketToVariation(experiment: Experiment, bucketingId: String) -> Variation? {
+    
+    func bucketToVariation(experiment: Experiment,
+                           bucketingId: String) -> DecisionResponse<Variation> {
+        let reasons = DecisionReasons()
+        
         let hashId = makeHashIdFromBucketingId(bucketingId: bucketingId, entityId: experiment.id)
         let bucketValue = generateBucketValue(bucketingId: hashId)
         logger.d(.userAssignedToBucketValue(bucketValue, bucketingId))
-
+        
         if experiment.trafficAllocation.count == 0 {
-            logger.e(.experimentHasNoTrafficAllocation(experiment.key))
-            return nil
+            let info = OptimizelyError.experimentHasNoTrafficAllocation(experiment.key)
+            logger.e(info)
+            reasons.addInfo(info)
+            return DecisionResponse(result: nil, reasons: reasons)
         }
-
+        
         if let variationId = allocateTraffic(trafficAllocation: experiment.trafficAllocation, bucketValue: bucketValue) {
             if let variation = experiment.getVariation(id: variationId) {
-                return variation
+                return DecisionResponse(result: variation, reasons: reasons)
             } else {
-                logger.e(.userBucketedIntoInvalidVariation(variationId))
-                return nil
+                let info = LogMessage.userBucketedIntoInvalidVariation(variationId)
+                logger.e(info)
+                reasons.addInfo(info)
+                return DecisionResponse(result: nil, reasons: reasons)
             }
         } else {
-            return nil
+            return DecisionResponse(result: nil, reasons: reasons)
         }
     }
     
     func allocateTraffic(trafficAllocation: [TrafficAllocation], bucketValue: Int) -> String? {
-        for bucket in trafficAllocation {
-            if bucketValue < bucket.endOfRange {
-                return bucket.entityId
-            }
+        for bucket in trafficAllocation where bucketValue < bucket.endOfRange {
+            return bucket.entityId
         }
         
         return nil
diff --git a/Sources/Implementation/DefaultDecisionService.swift b/Sources/Implementation/DefaultDecisionService.swift
index 4a33c2344..0e595672c 100644
--- a/Sources/Implementation/DefaultDecisionService.swift
+++ b/Sources/Implementation/DefaultDecisionService.swift
@@ -1,5 +1,5 @@
 /****************************************************************************
- * Copyright 2019-2020, Optimizely, Inc. and contributors                   *
+ * Copyright 2019-2021, Optimizely, Inc. and contributors                   *
  *                                                                          *
  * Licensed under the Apache License, Version 2.0 (the "License");          *
  * you may not use this file except in compliance with the License.         *
@@ -16,6 +16,12 @@
 
 import Foundation
 
+struct FeatureDecision {
+    let experiment: Experiment
+    let variation: Variation
+    let source: String
+}
+
 class DefaultDecisionService: OPTDecisionService {
     
     let bucketer: OPTBucketer
@@ -27,7 +33,13 @@ class DefaultDecisionService: OPTDecisionService {
         self.userProfileService = userProfileService
     }
     
-    func getVariation(config: ProjectConfig, userId: String, experiment: Experiment, attributes: OptimizelyAttributes) -> Variation? {
+    func getVariation(config: ProjectConfig,
+                      experiment: Experiment,
+                      userId: String,
+                      attributes: OptimizelyAttributes,
+                      options: [OptimizelyDecideOption]? = nil) -> DecisionResponse<Variation> {
+        let reasons = DecisionReasons(options: options)
+        
         let experimentId = experiment.id
         
         // Acquire bucketingId .
@@ -35,56 +47,93 @@ class DefaultDecisionService: OPTDecisionService {
         
         // ---- check if the experiment is running ----
         if !experiment.isActivated {
-            logger.i(.experimentNotRunning(experiment.key))
-            return nil
+            let info = LogMessage.experimentNotRunning(experiment.key)
+            logger.i(info)
+            reasons.addInfo(info)
+            return DecisionResponse(result: nil, reasons: reasons)
         }
         
         // ---- check if the user is forced into a variation ----
-        if let variationId = config.getForcedVariation(experimentKey: experiment.key, userId: userId)?.id,
+        let decisionResponse = config.getForcedVariation(experimentKey: experiment.key, userId: userId)
+        reasons.merge(decisionResponse.reasons)
+        if let variationId = decisionResponse.result?.id,
            let variation = experiment.getVariation(id: variationId) {
-            return variation
+            return DecisionResponse(result: variation, reasons: reasons)
         }
         
         // ---- check to see if user is white-listed for a certain variation ----
         if let variationKey = experiment.forcedVariations[userId] {
             if let variation = experiment.getVariation(key: variationKey) {
-                logger.i(.forcedVariationFound(variationKey, userId))
-                return variation
+                let info = LogMessage.forcedVariationFound(variationKey, userId)
+                logger.i(info)
+                reasons.addInfo(info)
+                return DecisionResponse(result: variation, reasons: reasons)
             }
             
-            // mapped to invalid variation - ignore and continue for other decisions
-            logger.e(.forcedVariationFoundButInvalid(variationKey, userId))
+            // mapped to invalid variation - ignore and continue for other deciesions
+            let info = LogMessage.forcedVariationFoundButInvalid(variationKey, userId)
+            logger.e(info)
+            reasons.addInfo(info)
         }
         
         // ---- check if a valid variation is stored in the user profile ----
-        if let variationId = self.getVariationIdFromProfile(userId: userId, experimentId: experimentId),
+        let ignoreUPS = (options ?? []).contains(.ignoreUserProfileService)
+        
+        if !ignoreUPS,
+           let variationId = getVariationIdFromProfile(userId: userId, experimentId: experimentId),
            let variation = experiment.getVariation(id: variationId) {
-            logger.i(.gotVariationFromUserProfile(variation.key, experiment.key, userId))
-            return variation
+            
+            let info = LogMessage.gotVariationFromUserProfile(variation.key, experiment.key, userId)
+            logger.i(info)
+            reasons.addInfo(info)
+            return DecisionResponse(result: variation, reasons: reasons)
         }
         
         var bucketedVariation: Variation?
         // ---- check if the user passes audience targeting before bucketing ----
-        if doesMeetAudienceConditions(config: config, experiment: experiment, userId: userId, attributes: attributes) {
+        let audienceResponse = doesMeetAudienceConditions(config: config,
+                                                          experiment: experiment,
+                                                          userId: userId,
+                                                          attributes: attributes)
+        reasons.merge(audienceResponse.reasons)
+        if audienceResponse.result ?? false {
             // bucket user into a variation
-            bucketedVariation = bucketer.bucketExperiment(config: config, experiment: experiment, bucketingId: bucketingId)
+            let decisionResponse = bucketer.bucketExperiment(config: config,
+                                                             experiment: experiment,
+                                                             bucketingId: bucketingId)
+            reasons.merge(decisionResponse.reasons)
+            bucketedVariation = decisionResponse.result
             
-            if let bucketedVariation = bucketedVariation {
-                logger.i(.userBucketedIntoVariationInExperiment(userId, experiment.key, bucketedVariation.key))
+            if let variation = bucketedVariation {
+                let info = LogMessage.userBucketedIntoVariationInExperiment(userId, experiment.key, variation.key)
+                logger.i(info)
+                reasons.addInfo(info)
                 // save to user profile
-                self.saveProfile(userId: userId, experimentId: experimentId, variationId: bucketedVariation.id)
+                if !ignoreUPS {
+                    self.saveProfile(userId: userId, experimentId: experimentId, variationId: variation.id)
+                }
             } else {
-                logger.i(.userNotBucketedIntoVariation(userId))
+                let info = LogMessage.userNotBucketedIntoVariation(userId)
+                logger.i(info)
+                reasons.addInfo(info)
             }
             
         } else {
-            logger.i(.userNotInExperiment(userId, experiment.key))
+            let info = LogMessage.userNotInExperiment(userId, experiment.key)
+            logger.i(info)
+            reasons.addInfo(info)
         }
         
-        return bucketedVariation
+        return DecisionResponse(result: bucketedVariation, reasons: reasons)
     }
     
-    func doesMeetAudienceConditions(config: ProjectConfig, experiment: Experiment, userId: String, attributes: OptimizelyAttributes, logType: Constants.EvaluationLogType = .experiment, loggingKey: String? = nil) -> Bool {
+    func doesMeetAudienceConditions(config: ProjectConfig,
+                                    experiment: Experiment,
+                                    userId: String,
+                                    attributes: OptimizelyAttributes,
+                                    logType: Constants.EvaluationLogType = .experiment,
+                                    loggingKey: String? = nil) -> DecisionResponse<Bool> {
+        let reasons = DecisionReasons()
         
         var result = true   // success as default (no condition, etc)
         let evType = logType.rawValue
@@ -122,108 +171,187 @@ class DefaultDecisionService: OPTDecisionService {
                 result = try holder.evaluate(project: config.project, attributes: attributes)
             }
         } catch {
-            logger.i(error as? OptimizelyError)
+            if let error = error as? OptimizelyError {
+                logger.i(error)
+                reasons.addInfo(error)
+            }
             result = false
         }
         
         logger.i(.audienceEvaluationResultCombined(evType, finalLoggingKey, result.description))
         
-        return result
+        return DecisionResponse(result: result, reasons: reasons)
     }
     
-    func getVariationForFeature(config: ProjectConfig, featureFlag: FeatureFlag, userId: String, attributes: OptimizelyAttributes) -> (experiment: Experiment, variation: Variation, source: String)? {
+    func getVariationForFeature(config: ProjectConfig,
+                                featureFlag: FeatureFlag,
+                                userId: String,
+                                attributes: OptimizelyAttributes,
+                                options: [OptimizelyDecideOption]? = nil) -> DecisionResponse<FeatureDecision> {
+        let reasons = DecisionReasons(options: options)
+        
         //Evaluate in this order:
         
         //1. Attempt to bucket user into experiment using feature flag.
         // Check if the feature flag is under an experiment and the the user is bucketed into one of these experiments
-        if let pair = getVariationForFeatureExperiment(config: config, featureFlag: featureFlag, userId: userId, attributes: attributes) {
-            return pair
+        var decisionResponse = getVariationForFeatureExperiment(config: config,
+                                                                featureFlag: featureFlag,
+                                                                userId: userId,
+                                                                attributes: attributes,
+                                                                options: options)
+        reasons.merge(decisionResponse.reasons)
+        if let decision = decisionResponse.result {
+            return DecisionResponse(result: decision, reasons: reasons)
         }
         
         //2. Attempt to bucket user into rollout using the feature flag.
         // Check if the feature flag has rollout and the user is bucketed into one of it's rules
-        if let pair = getVariationForFeatureRollout(config: config, featureFlag: featureFlag, userId: userId, attributes: attributes) {
-            return pair
+        decisionResponse = getVariationForFeatureRollout(config: config,
+                                                         featureFlag: featureFlag,
+                                                         userId: userId,
+                                                         attributes: attributes,
+                                                         options: options)
+        reasons.merge(decisionResponse.reasons)
+        if let decision = decisionResponse.result {
+            return DecisionResponse(result: decision, reasons: reasons)
         }
         
-        return nil
+        return DecisionResponse(result: nil, reasons: reasons)
         
     }
     
     func getVariationForFeatureExperiment(config: ProjectConfig,
                                           featureFlag: FeatureFlag,
                                           userId: String,
-                                          attributes: OptimizelyAttributes) -> (experiment: Experiment, variation: Variation, source: String)? {
+                                          attributes: OptimizelyAttributes,
+                                          options: [OptimizelyDecideOption]? = nil) -> DecisionResponse<FeatureDecision> {
+        let reasons = DecisionReasons(options: options)
         
         let experimentIds = featureFlag.experimentIds
         if experimentIds.isEmpty {
-            logger.d(.featureHasNoExperiments(featureFlag.key))
+            let info = LogMessage.featureHasNoExperiments(featureFlag.key)
+            logger.d(info)
+            reasons.addInfo(info)
         }
         
         // Check if there are any experiment IDs inside feature flag
         // Evaluate each experiment ID and return the first bucketed experiment variation
         for experimentId in experimentIds {
-            if let experiment = config.getExperiment(id: experimentId),
-               let variation = getVariation(config: config, userId: userId, experiment: experiment, attributes: attributes) {
-                return (experiment, variation, Constants.DecisionSource.featureTest.rawValue)
+            if let experiment = config.getExperiment(id: experimentId) {
+                let decisionResponse = getVariation(config: config,
+                                                    experiment: experiment,
+                                                    userId: userId,
+                                                    attributes: attributes,
+                                                    options: options)
+                reasons.merge(decisionResponse.reasons)
+                if let variation = decisionResponse.result {
+                    let featureDecision = FeatureDecision(experiment: experiment, variation: variation, source: Constants.DecisionSource.featureTest.rawValue)
+                    return DecisionResponse(result: featureDecision, reasons: reasons)
+                }
             }
         }
-        return nil
+        
+        return DecisionResponse(result: nil, reasons: reasons)
     }
     
     func getVariationForFeatureRollout(config: ProjectConfig,
                                        featureFlag: FeatureFlag,
                                        userId: String,
-                                       attributes: OptimizelyAttributes) -> (experiment: Experiment, variation: Variation, source: String)? {
+                                       attributes: OptimizelyAttributes,
+                                       options: [OptimizelyDecideOption]? = nil) -> DecisionResponse<FeatureDecision> {
+        let reasons = DecisionReasons(options: options)
         
         let bucketingId = getBucketingId(userId: userId, attributes: attributes)
         
         let rolloutId = featureFlag.rolloutId.trimmingCharacters(in: CharacterSet.whitespaces)
         
         guard !rolloutId.isEmpty else {
-            logger.d(.noRolloutExists(featureFlag.key))
-            return nil
+            let info = LogMessage.noRolloutExists(featureFlag.key)
+            logger.d(info)
+            reasons.addInfo(info)
+            return DecisionResponse(result: nil, reasons: reasons)
         }
         
         guard let rollout = config.getRollout(id: rolloutId) else {
-            logger.d(.rolloutIdInvalid(rolloutId, featureFlag.key))
-            return nil
+            let info = OptimizelyError.rolloutIdInvalid(rolloutId, featureFlag.key)
+            logger.d(info)
+            reasons.addInfo(info)
+            return DecisionResponse(result: nil, reasons: reasons)
         }
         
         let rolloutRules = rollout.experiments
         if rolloutRules.isEmpty {
-            logger.e(.rolloutHasNoExperiments(rolloutId))
-            return nil
+            let info = LogMessage.rolloutHasNoExperiments(rolloutId)
+            logger.e(info)
+            reasons.addInfo(info)
+            return DecisionResponse(result: nil, reasons: reasons)
         }
         
         // Evaluate all rollout rules except for last one
         for index in 0..<rolloutRules.count.advanced(by: -1) {
             let loggingKey = index + 1
             let experiment = rolloutRules[index]
-            if doesMeetAudienceConditions(config: config, experiment: experiment, userId: userId, attributes: attributes, logType: .rolloutRule, loggingKey: "\(loggingKey)") {
-                logger.d(.userMeetsConditionsForTargetingRule(userId, loggingKey))
-                if let variation = bucketer.bucketExperiment(config: config, experiment: experiment, bucketingId: bucketingId) {
-                    logger.d(.userBucketedIntoTargetingRule(userId, loggingKey))
-                    return (experiment, variation, Constants.DecisionSource.rollout.rawValue)
+            let decisionResponse = doesMeetAudienceConditions(config: config,
+                                                              experiment: experiment,
+                                                              userId: userId,
+                                                              attributes: attributes,
+                                                              logType: .rolloutRule,
+                                                              loggingKey: String(loggingKey))
+            reasons.merge(decisionResponse.reasons)
+            if decisionResponse.result ?? false {
+                var info = LogMessage.userMeetsConditionsForTargetingRule(userId, loggingKey)
+                logger.d(info)
+                reasons.addInfo(info)
+                
+                let decisionResponse = bucketer.bucketExperiment(config: config,
+                                                                 experiment: experiment,
+                                                                 bucketingId: bucketingId)
+                reasons.merge(decisionResponse.reasons)
+                if let variation = decisionResponse.result {
+                    info = LogMessage.userBucketedIntoTargetingRule(userId, loggingKey)
+                    logger.d(info)
+                    reasons.addInfo(info)
+                    
+                    let featureDecision = FeatureDecision(experiment: experiment, variation: variation, source: Constants.DecisionSource.rollout.rawValue)
+                    return DecisionResponse(result: featureDecision, reasons: reasons)
                 }
-                logger.d(.userNotBucketedIntoTargetingRule(userId, loggingKey))
+                info = LogMessage.userNotBucketedIntoTargetingRule(userId, loggingKey)
+                logger.d(info)
+                reasons.addInfo(info)
                 break
             } else {
-                logger.d(.userDoesntMeetConditionsForTargetingRule(userId, loggingKey))
+                let info = LogMessage.userDoesntMeetConditionsForTargetingRule(userId, loggingKey)
+                logger.d(info)
+                reasons.addInfo(info)
             }
         }
+        
         // Evaluate fall back rule / last rule now
         let experiment = rolloutRules[rolloutRules.count - 1]
         
-        if doesMeetAudienceConditions(config: config, experiment: experiment, userId: userId, attributes: attributes, logType: .rolloutRule, loggingKey: "Everyone Else") {
-            if let variation = bucketer.bucketExperiment(config: config, experiment: experiment, bucketingId: bucketingId) {
-                logger.d(.userBucketedIntoEveryoneTargetingRule(userId))
+        let decisionResponse = doesMeetAudienceConditions(config: config,
+                                                          experiment: experiment,
+                                                          userId: userId,
+                                                          attributes: attributes,
+                                                          logType: .rolloutRule,
+                                                          loggingKey: "Everyone Else")
+        reasons.merge(decisionResponse.reasons)
+        if decisionResponse.result ?? false {
+            let decisionResponse = bucketer.bucketExperiment(config: config,
+                                                             experiment: experiment,
+                                                             bucketingId: bucketingId)
+            reasons.merge(decisionResponse.reasons)
+            if let variation = decisionResponse.result {
+                let info = LogMessage.userBucketedIntoEveryoneTargetingRule(userId)
+                logger.d(info)
+                reasons.addInfo(info)
                 
-                return (experiment, variation, Constants.DecisionSource.rollout.rawValue)
+                let featureDecision = FeatureDecision(experiment: experiment, variation: variation, source: Constants.DecisionSource.rollout.rawValue)
+                return DecisionResponse(result: featureDecision, reasons: reasons)
             }
         }
         
-        return nil
+        return DecisionResponse(result: nil, reasons: reasons)
     }
     
     func getBucketingId(userId: String, attributes: OptimizelyAttributes) -> String {
@@ -245,7 +373,8 @@ class DefaultDecisionService: OPTDecisionService {
 
 extension DefaultDecisionService {
     
-    func getVariationIdFromProfile(userId: String, experimentId: String) -> String? {
+    func getVariationIdFromProfile(userId: String,
+                                   experimentId: String) -> String? {
         if let profile = userProfileService.lookup(userId: userId),
            let bucketMap = profile[UserProfileKeys.kBucketMap] as? OPTUserProfileService.UPBucketMap,
            let experimentMap = bucketMap[experimentId],
@@ -256,7 +385,9 @@ extension DefaultDecisionService {
         }
     }
     
-    func saveProfile(userId: String, experimentId: String, variationId: String) {
+    func saveProfile(userId: String,
+                     experimentId: String,
+                     variationId: String) {
         var profile = userProfileService.lookup(userId: userId) ?? OPTUserProfileService.UPProfile()
         
         var bucketMap = profile[UserProfileKeys.kBucketMap] as? OPTUserProfileService.UPBucketMap ?? OPTUserProfileService.UPBucketMap()
diff --git a/Sources/Optimizely+Decide/OptimizelyClient+Decide.swift b/Sources/Optimizely+Decide/OptimizelyClient+Decide.swift
new file mode 100644
index 000000000..98aabaf56
--- /dev/null
+++ b/Sources/Optimizely+Decide/OptimizelyClient+Decide.swift
@@ -0,0 +1,204 @@
+/****************************************************************************
+ * Copyright 2021, Optimizely, Inc. and contributors                        *
+ *                                                                          *
+ * Licensed under the Apache License, Version 2.0 (the "License");          *
+ * you may not use this file except in compliance with the License.         *
+ * You may obtain a copy of the License at                                  *
+ *                                                                          *
+ *    http://www.apache.org/licenses/LICENSE-2.0                            *
+ *                                                                          *
+ * Unless required by applicable law or agreed to in writing, software      *
+ * distributed under the License is distributed on an "AS IS" BASIS,        *
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. *
+ * See the License for the specific language governing permissions and      *
+ * limitations under the License.                                           *
+ ***************************************************************************/
+
+import Foundation
+
+extension OptimizelyClient {
+    
+    /// Create a context of the user for which decision APIs will be called.
+    ///
+    /// A user context will be created successfully even when the SDK is not fully configured yet.
+    ///
+    /// - Parameters:
+    ///   - userId: The user ID to be used for bucketing.
+    ///   - attributes: A map of attribute names to current user attribute values.
+    /// - Returns: An OptimizelyUserContext associated with this OptimizelyClient
+    public func createUserContext(userId: String,
+                                  attributes: [String: Any]? = nil) -> OptimizelyUserContext {
+        return OptimizelyUserContext(optimizely: self, userId: userId, attributes: attributes)
+    }
+    
+    func decide(user: OptimizelyUserContext,
+                key: String,
+                options: [OptimizelyDecideOption]? = nil) -> OptimizelyDecision {
+        
+        guard let config = self.config else {
+            return OptimizelyDecision.errorDecision(key: key, user: user, error: .sdkNotReady)
+        }
+        
+        guard let feature = config.getFeatureFlag(key: key) else {
+            return OptimizelyDecision.errorDecision(key: key, user: user, error: .featureKeyInvalid(key))
+        }
+        
+        let userId = user.userId
+        let attributes = user.attributes
+        let allOptions = defaultDecideOptions + (options ?? [])
+        let reasons = DecisionReasons(options: allOptions)
+        var decisionEventDispatched = false
+        var enabled = false
+        
+        let decisionResponse = decisionService.getVariationForFeature(config: config,
+                                                                      featureFlag: feature,
+                                                                      userId: userId,
+                                                                      attributes: attributes,
+                                                                      options: allOptions)
+        reasons.merge(decisionResponse.reasons)
+        let decision = decisionResponse.result
+        if let featureEnabled = decision?.variation.featureEnabled {
+            enabled = featureEnabled
+        }
+        
+        if !allOptions.contains(.disableDecisionEvent) {
+            sendImpressionEvent(experiment: decision?.experiment,
+                                variation: decision?.variation,
+                                userId: userId,
+                                attributes: attributes,
+                                flagKey: feature.key,
+                                ruleType: decision?.source ?? Constants.DecisionSource.rollout.rawValue,
+                                enabled: enabled)
+            decisionEventDispatched = true
+        }
+        
+        var variableMap = [String: Any]()
+        if !allOptions.contains(.excludeVariables) {
+            let decisionResponse = getDecisionVariableMap(feature: feature,
+                                                          variation: decision?.variation,
+                                                          enabled: enabled)
+            reasons.merge(decisionResponse.reasons)
+            variableMap = decisionResponse.result ?? [:]
+        }
+        
+        var optimizelyJSON: OptimizelyJSON
+        if let opt = OptimizelyJSON(map: variableMap) {
+            optimizelyJSON = opt
+        } else {
+            reasons.addError(OptimizelyError.invalidJSONVariable)
+            optimizelyJSON = OptimizelyJSON.createEmpty()
+        }
+        
+        // TODO: add ruleKey values when available later. Use a copy of experimentKey for now.
+        let ruleKey = decision?.experiment.key
+        let reasonsToReport = reasons.toReport()
+        
+        sendDecisionNotification(userId: userId,
+                                 attributes: attributes,
+                                 decisionInfo: DecisionInfo(decisionType: .flag,
+                                                            experiment: decision?.experiment,
+                                                            variation: decision?.variation,
+                                                            feature: feature,
+                                                            featureEnabled: enabled,
+                                                            variableValues: variableMap,
+                                                            ruleKey: ruleKey,
+                                                            reasons: reasonsToReport,
+                                                            decisionEventDispatched: decisionEventDispatched))
+        
+        return OptimizelyDecision(variationKey: decision?.variation.key,
+                                  enabled: enabled,
+                                  variables: optimizelyJSON,
+                                  ruleKey: ruleKey,
+                                  flagKey: feature.key,
+                                  userContext: user,
+                                  reasons: reasonsToReport)
+    }
+    
+    func decide(user: OptimizelyUserContext,
+                keys: [String],
+                options: [OptimizelyDecideOption]? = nil) -> [String: OptimizelyDecision] {
+        guard config != nil else {
+            logger.e(OptimizelyError.sdkNotReady)
+            return [:]
+        }
+        
+        guard keys.count > 0 else { return [:] }
+        
+        let allOptions = defaultDecideOptions + (options ?? [])
+        
+        var decisions = [String: OptimizelyDecision]()
+        
+        let enabledFlagsOnly = allOptions.contains(.enabledFlagsOnly)
+        keys.forEach { key in
+            let decision = decide(user: user, key: key, options: options)
+            if !enabledFlagsOnly || decision.enabled {
+                decisions[key] = decision
+            }
+        }
+        
+        return decisions
+    }
+    
+    func decideAll(user: OptimizelyUserContext,
+                   options: [OptimizelyDecideOption]? = nil) -> [String: OptimizelyDecision] {
+        guard let config = self.config else {
+            logger.e(OptimizelyError.sdkNotReady)
+            return [:]
+        }
+        
+        return decide(user: user, keys: config.featureFlagKeys, options: options)
+    }
+    
+}
+
+// MARK: - Utils
+
+extension OptimizelyClient {
+    
+    func getDecisionVariableMap(feature: FeatureFlag,
+                                variation: Variation?,
+                                enabled: Bool) -> DecisionResponse<[String: Any]> {
+        let reasons = DecisionReasons()
+        
+        var variableMap = [String: Any]()
+        
+        for (_, v) in feature.variablesMap {
+            var featureValue = v.value
+            if enabled, let variable = variation?.getVariable(id: v.id) {
+                featureValue = variable.value
+            }
+            
+            if let value = parseFeatureVaraible(value: featureValue, type: v.type) {
+                variableMap[v.key] = value
+            } else {
+                let info = OptimizelyError.variableValueInvalid(v.key)
+                logger.e(info)
+                reasons.addError(info)
+            }
+        }
+        
+        return DecisionResponse(result: variableMap, reasons: reasons)
+    }
+    
+    func parseFeatureVaraible(value: String, type: String) -> Any? {
+        var valueParsed: Any? = value
+        
+        if let valueType = Constants.VariableValueType(rawValue: type) {
+            switch valueType {
+            case .string:
+                break
+            case .integer:
+                valueParsed = Int(value)
+            case .double:
+                valueParsed = Double(value)
+            case .boolean:
+                valueParsed = Bool(value)
+            case .json:
+                valueParsed = OptimizelyJSON(payload: value)?.toMap()
+            }
+        }
+        
+        return valueParsed
+    }
+    
+}
diff --git a/Sources/Optimizely+Decide/OptimizelyDecideOption.swift b/Sources/Optimizely+Decide/OptimizelyDecideOption.swift
new file mode 100644
index 000000000..6bc9af1c9
--- /dev/null
+++ b/Sources/Optimizely+Decide/OptimizelyDecideOption.swift
@@ -0,0 +1,35 @@
+/****************************************************************************
+* Copyright 2021, Optimizely, Inc. and contributors                        *
+*                                                                          *
+* Licensed under the Apache License, Version 2.0 (the "License");          *
+* you may not use this file except in compliance with the License.         *
+* You may obtain a copy of the License at                                  *
+*                                                                          *
+*    http://www.apache.org/licenses/LICENSE-2.0                            *
+*                                                                          *
+* Unless required by applicable law or agreed to in writing, software      *
+* distributed under the License is distributed on an "AS IS" BASIS,        *
+* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. *
+* See the License for the specific language governing permissions and      *
+* limitations under the License.                                           *
+***************************************************************************/
+    
+import Foundation
+
+/// Options controlling flag decisions.
+@objc public enum OptimizelyDecideOption: Int {
+    /// disable decision event tracking.
+    case disableDecisionEvent
+    
+    /// return decisions only for flags which are enabled (decideAll only).
+    case enabledFlagsOnly
+    
+    /// skip user profile service for decision.
+    case ignoreUserProfileService
+    
+    /// include info and debug messages in the decision reasons.
+    case includeReasons
+    
+    /// exclude variable values from the decision result.
+    case excludeVariables
+}
diff --git a/Sources/Optimizely+Decide/OptimizelyDecision.swift b/Sources/Optimizely+Decide/OptimizelyDecision.swift
new file mode 100644
index 000000000..3681931e0
--- /dev/null
+++ b/Sources/Optimizely+Decide/OptimizelyDecision.swift
@@ -0,0 +1,70 @@
+/****************************************************************************
+* Copyright 2021, Optimizely, Inc. and contributors                        *
+*                                                                          *
+* Licensed under the Apache License, Version 2.0 (the "License");          *
+* you may not use this file except in compliance with the License.         *
+* You may obtain a copy of the License at                                  *
+*                                                                          *
+*    http://www.apache.org/licenses/LICENSE-2.0                            *
+*                                                                          *
+* Unless required by applicable law or agreed to in writing, software      *
+* distributed under the License is distributed on an "AS IS" BASIS,        *
+* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. *
+* See the License for the specific language governing permissions and      *
+* limitations under the License.                                           *
+***************************************************************************/
+    
+import Foundation
+
+/// A decision struct that the SDK makes for a flag key and a user context.
+public struct OptimizelyDecision {
+    
+    /// The variation key of the decision. This value will be nil when decision making fails.
+    public let variationKey: String?
+    
+    /// The boolean value indicating if the flag is enabled or not.
+    public let enabled: Bool
+    
+    /// The collection of variables associated with the decision.
+    public let variables: OptimizelyJSON
+    
+    /// The rule key of the decision.
+    public let ruleKey: String?
+
+    /// The flag key for which the decision has been made for.
+    public let flagKey: String
+    
+    /// A copy of the user context for which the decision has been made for.
+    public let userContext: OptimizelyUserContext
+    
+    /// An array of error/info messages describing why the decision has been made.
+    public let reasons: [String]
+}
+
+extension OptimizelyDecision {
+    static func errorDecision(key: String, user: OptimizelyUserContext, error: OptimizelyError) -> OptimizelyDecision {
+        return OptimizelyDecision(variationKey: nil,
+                                  enabled: false,
+                                  variables: OptimizelyJSON.createEmpty(),
+                                  ruleKey: nil,
+                                  flagKey: key,
+                                  userContext: user,
+                                  reasons: [error.reason])
+    }
+    
+    var hasFailed: Bool {
+        return variationKey == nil
+    }
+}
+
+extension OptimizelyDecision: Equatable {
+    public static func == (lhs: OptimizelyDecision, rhs: OptimizelyDecision) -> Bool {
+        return lhs.variationKey == rhs.variationKey &&
+            lhs.enabled == rhs.enabled &&
+            lhs.variables == rhs.variables &&
+            lhs.ruleKey == rhs.ruleKey &&
+            lhs.flagKey == rhs.flagKey &&
+            lhs.userContext == rhs.userContext &&
+            lhs.reasons == rhs.reasons
+    }
+}
diff --git a/Sources/Optimizely+Decide/OptimizelyUserContext+ObjC.swift b/Sources/Optimizely+Decide/OptimizelyUserContext+ObjC.swift
new file mode 100644
index 000000000..3165e2b0a
--- /dev/null
+++ b/Sources/Optimizely+Decide/OptimizelyUserContext+ObjC.swift
@@ -0,0 +1,125 @@
+/****************************************************************************
+* Copyright 2021, Optimizely, Inc. and contributors                        *
+*                                                                          *
+* Licensed under the Apache License, Version 2.0 (the "License");          *
+* you may not use this file except in compliance with the License.         *
+* You may obtain a copy of the License at                                  *
+*                                                                          *
+*    http://www.apache.org/licenses/LICENSE-2.0                            *
+*                                                                          *
+* Unless required by applicable law or agreed to in writing, software      *
+* distributed under the License is distributed on an "AS IS" BASIS,        *
+* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. *
+* See the License for the specific language governing permissions and      *
+* limitations under the License.                                           *
+***************************************************************************/
+
+import Foundation
+
+@objc(OptimizelyUserContext)
+@objcMembers public class ObjcOptimizelyUserContext: NSObject {
+    var userContext: OptimizelyUserContext
+    
+    public var userId: String {
+        return userContext.userId
+    }
+    
+    public var attributes: [String: Any] {
+        return userContext.attributes as [String : Any]
+    }
+    
+    public var optimizely: OptimizelyClient? {
+        return userContext.optimizely
+    }
+
+    public init(optimizely: OptimizelyClient, userId: String, attributes: [String: Any]? = nil) {
+        userContext = OptimizelyUserContext(optimizely: optimizely, userId: userId, attributes: attributes)
+    }
+    
+    public init(user: OptimizelyUserContext) {
+        self.userContext = user
+    }
+
+    public func setAttribute(key: String, value: Any) {
+        userContext.setAttribute(key: key, value: value)
+    }
+    
+    public func decide(key: String, options: [Int]? = nil) -> ObjcOptimizelyDecision {
+        let decision = userContext.decide(key: key, options: mapOptionsObjcToSwift(options))
+        return ObjcOptimizelyDecision(decision: decision)
+    }
+    
+    public func decide(keys: [String], options: [Int]? = nil) -> [String: ObjcOptimizelyDecision] {
+        let decisionsMap = userContext.decide(keys: keys, options: mapOptionsObjcToSwift(options))
+        return decisionsMap.mapValues { ObjcOptimizelyDecision(decision: $0) }
+    }
+    
+    public func decideAll(options: [Int]? = nil) -> [String: ObjcOptimizelyDecision] {
+        let decisionsMap = userContext.decideAll(options: mapOptionsObjcToSwift(options))
+        return decisionsMap.mapValues { ObjcOptimizelyDecision(decision: $0) }
+    }
+    
+    public func trackEvent(eventKey: String, eventTags: [String: Any]? = nil) throws {
+        try userContext.trackEvent(eventKey: eventKey, eventTags: eventTags)
+    }
+
+}
+
+@objc(OptimizelyDecision)
+@objcMembers public class ObjcOptimizelyDecision: NSObject {
+    public let variationKey: String?
+    public let enabled: Bool
+    public let variables: OptimizelyJSON
+    public let ruleKey: String?
+
+    public let flagKey: String
+    public let userContext: ObjcOptimizelyUserContext
+    public let reasons: [String]
+    
+    init(decision: OptimizelyDecision) {
+        variationKey = decision.variationKey
+        variables = decision.variables
+        enabled = decision.enabled
+        ruleKey = decision.ruleKey
+        
+        flagKey = decision.flagKey
+        userContext = ObjcOptimizelyUserContext(user: decision.userContext)
+        reasons = decision.reasons
+    }
+}
+
+extension OptimizelyClient {
+    
+    @available(swift, obsoleted: 1.0)
+    @objc(createUserContextWithUserId:attributes:)
+    public func objcCreateUserContext(userId: String, attributes: [String: Any]? = nil) -> ObjcOptimizelyUserContext {
+        let user = createUserContext(userId: userId, attributes: attributes)
+        return ObjcOptimizelyUserContext(user: user)
+    }
+    
+    @available(swift, obsoleted: 1.0)
+    @objc public convenience init(sdkKey: String,
+                                  logger: OPTLogger?,
+                                  eventDispatcher: _ObjcOPTEventDispatcher?,
+                                  userProfileService: OPTUserProfileService?,
+                                  periodicDownloadInterval: NSNumber?,
+                                  defaultLogLevel: OptimizelyLogLevel,
+                                  defaultDecideOptions: [Int]?) {
+        self.init(sdkKey: sdkKey,
+                  logger: logger,
+                  eventDispatcher: SwiftEventDispatcher(eventDispatcher),
+                  userProfileService: userProfileService,
+                  periodicDownloadInterval: periodicDownloadInterval?.intValue,
+                  defaultLogLevel: defaultLogLevel,
+                  defaultDecideOptions: mapOptionsObjcToSwift(defaultDecideOptions))
+    }
+
+}
+
+fileprivate func mapOptionsObjcToSwift(_ options: [Int]?) -> [OptimizelyDecideOption]? {
+    return options?.compactMap { OptimizelyDecideOption(rawValue: $0) }
+}
+
+fileprivate func mapOptionsSwiftToObjc(_ options: [OptimizelyDecideOption]?) -> [Int]? {
+    return options?.compactMap { $0.rawValue }
+}
diff --git a/Sources/Optimizely+Decide/OptimizelyUserContext.swift b/Sources/Optimizely+Decide/OptimizelyUserContext.swift
new file mode 100644
index 000000000..755dc9aec
--- /dev/null
+++ b/Sources/Optimizely+Decide/OptimizelyUserContext.swift
@@ -0,0 +1,141 @@
+/****************************************************************************
+* Copyright 2021, Optimizely, Inc. and contributors                        *
+*                                                                          *
+* Licensed under the Apache License, Version 2.0 (the "License");          *
+* you may not use this file except in compliance with the License.         *
+* You may obtain a copy of the License at                                  *
+*                                                                          *
+*    http://www.apache.org/licenses/LICENSE-2.0                            *
+*                                                                          *
+* Unless required by applicable law or agreed to in writing, software      *
+* distributed under the License is distributed on an "AS IS" BASIS,        *
+* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. *
+* See the License for the specific language governing permissions and      *
+* limitations under the License.                                           *
+***************************************************************************/
+
+import Foundation
+
+/// An object for user contexts that the SDK will use to make decisions for.
+public class OptimizelyUserContext {
+    weak var optimizely: OptimizelyClient?
+    public var userId: String
+    
+    var atomicAttributes: AtomicProperty<[String: Any?]>
+    public var attributes: [String: Any?] {
+        return atomicAttributes.property ?? [:]
+    }
+    
+    var clone: OptimizelyUserContext? {
+        guard let optimizely = self.optimizely else { return nil }
+        return OptimizelyUserContext(optimizely: optimizely, userId: userId, attributes: attributes)
+    }
+    
+    lazy var logger = OPTLoggerFactory.getLogger()
+    
+    /// OptimizelyUserContext init
+    ///
+    /// - Parameters:
+    ///   - optimizely: An instance of OptimizelyClient to be used for decisions.
+    ///   - userId: The user ID to be used for bucketing.
+    ///   - attributes: A map of attribute names to current user attribute values.
+    public init(optimizely: OptimizelyClient,
+                userId: String,
+                attributes: [String: Any?]? = nil) {
+        self.optimizely = optimizely
+        self.userId = userId
+        self.atomicAttributes = AtomicProperty(property: attributes ?? [:])
+    }
+    
+    /// Set an attribute for a given key.
+    /// - Parameters:
+    ///   - key: An attribute key
+    ///   - value: An attribute value
+    public func setAttribute(key: String, value: Any?) {
+        atomicAttributes.performAtomic { attributes in
+            attributes[key] = value
+        }
+    }
+    
+    /// Returns a decision result for a given flag key and a user context, which contains all data required to deliver the flag or experiment.
+    ///
+    /// If the SDK finds an error (__sdkNotReady__, etc), it’ll return a decision with `nil` for `enabled` and `variationKey`. The decision will include an error message in `reasons` (regardless of the __includeReasons__ option).
+    ///
+    /// - Parameters:
+    ///   - key: A flag key for which a decision will be made.
+    ///   - user: A user context. This is optional when a user context has been set before.
+    ///   - options: An array of options for decision-making.
+    /// - Returns: A decision result.
+    public func decide(key: String,
+                       options: [OptimizelyDecideOption]? = nil) -> OptimizelyDecision {
+        
+        guard let optimizely = self.optimizely, let clone = self.clone else {
+            return OptimizelyDecision.errorDecision(key: key, user: self, error: .sdkNotReady)
+        }
+        
+        return optimizely.decide(user: clone, key: key, options: options)
+    }
+
+    /// Returns a key-map of decision results for multiple flag keys and a user context.
+    ///
+    /// - If the SDK finds an error (__flagKeyInvalid__, etc) for a key, the response will include a decision for the key showing `reasons` for the error (regardless of __includeReasons__ in options).
+    /// - The SDK will always return key-mapped decisions. When it can not process requests (on __sdkNotReady__ error), it’ll return an empty map after logging the errors.
+    ///
+    /// - Parameters:
+    ///   - keys: An array of flag keys for which decisions will be made. When set to `nil`, the SDK will return decisions for all active flag keys.
+    ///   - options: An array of options for decision-making.
+    /// - Returns: A dictionary of all decision results, mapped by flag keys.
+    public func decide(keys: [String],
+                       options: [OptimizelyDecideOption]? = nil) -> [String: OptimizelyDecision] {
+
+        guard let optimizely = self.optimizely, let clone = self.clone else {
+            logger.e(OptimizelyError.sdkNotReady)
+            return [:]
+        }
+        
+        return optimizely.decide(user: clone, keys: keys, options: options)
+    }
+    
+    /// Returns a key-map of decision results for all active flag keys.
+    ///
+    /// - Parameters:
+    ///   - options: An array of options for decision-making.
+    /// - Returns: A dictionary of all decision results, mapped by flag keys.
+    public func decideAll(options: [OptimizelyDecideOption]? = nil) -> [String: OptimizelyDecision] {
+        guard let optimizely = self.optimizely, let clone = self.clone else {
+            logger.e(OptimizelyError.sdkNotReady)
+            return [:]
+        }
+
+        return optimizely.decideAll(user: clone, options: options)
+    }
+
+    /// Track an event.
+    ///
+    /// - Parameters:
+    ///   - eventKey: The event name.
+    ///   - eventTags: A map of event tag names to event tag values (NSString or NSNumber containing float, double, integer, or boolean).
+    /// - Throws: `OptimizelyError` if an error is detected.
+    public func trackEvent(eventKey: String,
+                           eventTags: OptimizelyEventTags? = nil) throws {
+        
+        guard let optimizely = self.optimizely, optimizely.config != nil else {
+            throw OptimizelyError.sdkNotReady
+        }
+
+        try optimizely.track(eventKey: eventKey,
+                             userId: userId,
+                             attributes: attributes,
+                             eventTags: eventTags)
+    }
+
+}
+
+extension OptimizelyUserContext: Equatable {
+    
+    public static func == (lhs: OptimizelyUserContext, rhs: OptimizelyUserContext) -> Bool {
+        return lhs.userId == rhs.userId &&
+            (lhs.attributes as NSDictionary).isEqual(to: rhs.attributes as [AnyHashable: Any])
+    }
+    
+}
diff --git a/Sources/Optimizely/OptimizelyClient.swift b/Sources/Optimizely/OptimizelyClient.swift
index 9be8fd43e..4c8d4df55 100644
--- a/Sources/Optimizely/OptimizelyClient.swift
+++ b/Sources/Optimizely/OptimizelyClient.swift
@@ -1,5 +1,5 @@
 /****************************************************************************
- * Copyright 2019-2020, Optimizely, Inc. and contributors                   *
+ * Copyright 2019-2021, Optimizely, Inc. and contributors                   *
  *                                                                          *
  * Licensed under the Apache License, Version 2.0 (the "License");          *
  * you may not use this file except in compliance with the License.         *
@@ -24,8 +24,8 @@ open class OptimizelyClient: NSObject {
     // MARK: - Properties
     
     var sdkKey: String
-    
-    private var atomicConfig: AtomicProperty<ProjectConfig> = AtomicProperty<ProjectConfig>()
+
+    private var atomicConfig = AtomicProperty<ProjectConfig>()
     var config: ProjectConfig? {
         get {
             return atomicConfig.property
@@ -35,6 +35,8 @@ open class OptimizelyClient: NSObject {
         }
     }
     
+    var defaultDecideOptions: [OptimizelyDecideOption]
+
     public var version: String {
         return Utils.sdkVersion
     }
@@ -81,13 +83,16 @@ open class OptimizelyClient: NSObject {
     ///   - eventDispatcher: custom EventDispatcher (optional)
     ///   - userProfileService: custom UserProfileService (optional)
     ///   - defaultLogLevel: default log level (optional. default = .info)
+    ///   - defaultDecisionOptions: default decision optiopns (optional)
     public init(sdkKey: String,
                 logger: OPTLogger? = nil,
                 eventDispatcher: OPTEventDispatcher? = nil,
                 userProfileService: OPTUserProfileService? = nil,
-                defaultLogLevel: OptimizelyLogLevel? = nil) {
+                defaultLogLevel: OptimizelyLogLevel? = nil,
+                defaultDecideOptions: [OptimizelyDecideOption]? = nil) {
         
         self.sdkKey = sdkKey
+        self.defaultDecideOptions = defaultDecideOptions ?? []
         
         super.init()
         
@@ -114,7 +119,14 @@ open class OptimizelyClient: NSObject {
     ///   - resourceTimeout: timeout for datafile download (optional)
     ///   - completion: callback when initialization is completed
     public func start(resourceTimeout: Double? = nil, completion: ((OptimizelyResult<Data>) -> Void)? = nil) {
-        datafileHandler?.downloadDatafile(sdkKey: sdkKey, returnCacheIfNoChange: true, resourceTimeoutInterval: resourceTimeout) { result in
+        datafileHandler?.downloadDatafile(sdkKey: sdkKey,
+                                          returnCacheIfNoChange: true,
+                                          resourceTimeoutInterval: resourceTimeout) { [weak self] result in
+            guard let self = self else {
+                completion?(.failure(.sdkNotReady))
+                return
+            }
+            
             switch result {
             case .success(let datafile):
                 guard let datafile = datafile else {
@@ -169,7 +181,9 @@ open class OptimizelyClient: NSObject {
         
         if !doFetchDatafileBackground { return }
         
-        datafileHandler?.downloadDatafile(sdkKey: sdkKey, returnCacheIfNoChange: false) { result in
+        datafileHandler?.downloadDatafile(sdkKey: sdkKey, returnCacheIfNoChange: false) { [weak self] result in
+            guard let self = self else { return }
+
             // override to update always if periodic datafile polling is enabled
             // this is necessary for the case that the first cache download gets the updated datafile
             guard doUpdateConfigOnNewDatafile || self.isPeriodicPollingEnabled else { return }
@@ -293,16 +307,17 @@ open class OptimizelyClient: NSObject {
         }
         
         let variation = decisionService.getVariation(config: config,
-                                                     userId: userId,
                                                      experiment: experiment,
-                                                     attributes: attributes ?? OptimizelyAttributes())
+                                                     userId: userId,
+                                                     attributes: attributes ?? OptimizelyAttributes(),
+                                                     options: nil).result
         
         let decisionType: Constants.DecisionType = config.isFeatureExperiment(id: experiment.id) ? .featureTest : .abTest
-        sendDecisionNotification(decisionType: decisionType,
-                                 userId: userId,
+        sendDecisionNotification(userId: userId,
                                  attributes: attributes,
-                                 experiment: experiment,
-                                 variation: variation)
+                                 decisionInfo: DecisionInfo(decisionType: decisionType,
+                                                            experiment: experiment,
+                                                            variation: variation))
         
         if let variation = variation {
             return variation
@@ -331,7 +346,7 @@ open class OptimizelyClient: NSObject {
     public func getForcedVariation(experimentKey: String, userId: String) -> String? {
         guard let config = self.config else { return nil }
         
-        let variaion = config.getForcedVariation(experimentKey: experimentKey, userId: userId)
+        let variaion = config.getForcedVariation(experimentKey: experimentKey, userId: userId).result
         return variaion?.key
     }
     
@@ -378,7 +393,8 @@ open class OptimizelyClient: NSObject {
         let pair = decisionService.getVariationForFeature(config: config,
                                                           featureFlag: featureFlag,
                                                           userId: userId,
-                                                          attributes: attributes ?? OptimizelyAttributes())
+                                                          attributes: attributes ?? OptimizelyAttributes(),
+                                                          options: nil).result
         
         let source = pair?.source ?? Constants.DecisionSource.rollout.rawValue
         let featureEnabled = pair?.variation.featureEnabled ?? false
@@ -387,18 +403,23 @@ open class OptimizelyClient: NSObject {
         } else {
             logger.i(.featureNotEnabledForUser(featureKey, userId))
         }
+
+        sendImpressionEvent(experiment: pair?.experiment,
+                            variation: pair?.variation,
+                            userId: userId,
+                            attributes: attributes,
+                            flagKey: featureKey,
+                            ruleType: source,
+                            enabled: featureEnabled)
         
-        sendImpressionEvent(experiment: pair?.experiment, variation: pair?.variation, userId: userId, attributes: attributes, flagKey: featureKey, ruleType: source, enabled: featureEnabled)
-        
-        sendDecisionNotification(decisionType: .feature,
-                                 userId: userId,
+        sendDecisionNotification(userId: userId,
                                  attributes: attributes,
-                                 experiment: pair?.experiment,
-                                 variation: pair?.variation,
-                                 source: source,
-                                 feature: featureFlag,
-                                 featureEnabled: featureEnabled)
-        
+                                 decisionInfo: DecisionInfo(decisionType: .feature,
+                                                            experiment: pair?.experiment,
+                                                            variation: pair?.variation,
+                                                            source: source,
+                                                            feature: featureFlag,
+                                                            featureEnabled: featureEnabled))
         return featureEnabled
     }
     
@@ -519,10 +540,11 @@ open class OptimizelyClient: NSObject {
         
         var featureValue = variable.defaultValue ?? ""
         
-        let decision = self.decisionService.getVariationForFeature(config: config,
+        let decision = decisionService.getVariationForFeature(config: config,
                                                                    featureFlag: featureFlag,
                                                                    userId: userId,
-                                                                   attributes: attributes ?? OptimizelyAttributes())
+                                                                   attributes: attributes ?? OptimizelyAttributes(),
+                                                                   options: nil).result
         if let decision = decision {
             if let featureVariable = decision.variation.variables?.filter({$0.id == variable.id}).first {
                 if let featureEnabled = decision.variation.featureEnabled, featureEnabled {
@@ -577,18 +599,17 @@ open class OptimizelyClient: NSObject {
         let variation = decision?.variation
         let featureEnabled = variation?.featureEnabled ?? false
         
-        sendDecisionNotification(decisionType: .featureVariable,
-                                 userId: userId,
+        sendDecisionNotification(userId: userId,
                                  attributes: attributes,
-                                 experiment: experiment,
-                                 variation: variation,
-                                 source: decision?.source,
-                                 feature: featureFlag,
-                                 featureEnabled: featureEnabled,
-                                 variableKey: variableKey,
-                                 variableType: variable.type,
-                                 variableValue: notificationValue)
-        
+                                 decisionInfo: DecisionInfo(decisionType: .featureVariable,
+                                                            experiment: experiment,
+                                                            variation: variation,
+                                                            source: decision?.source,
+                                                            feature: featureFlag,
+                                                            featureEnabled: featureEnabled,
+                                                            variableKey: variableKey,
+                                                            variableType: variable.type,
+                                                            variableValue: notificationValue))
         return value
     }
     
@@ -611,10 +632,11 @@ open class OptimizelyClient: NSObject {
             throw OptimizelyError.featureKeyInvalid(featureKey)
         }
         
-        let decision = self.decisionService.getVariationForFeature(config: config,
+        let decision = decisionService.getVariationForFeature(config: config,
                                                                    featureFlag: featureFlag,
                                                                    userId: userId,
-                                                                   attributes: attributes ?? OptimizelyAttributes())
+                                                                   attributes: attributes ?? OptimizelyAttributes(),
+                                                                   options: nil).result
         if let featureEnabled = decision?.variation.featureEnabled {
             enabled = featureEnabled
             if featureEnabled {
@@ -640,16 +662,12 @@ open class OptimizelyClient: NSObject {
                     break
                 case .integer:
                     valueParsed = Int(featureValue)
-                    break
                 case .double:
                     valueParsed = Double(featureValue)
-                    break
                 case .boolean:
                     valueParsed = Bool(featureValue)
-                    break
                 case .json:
                     valueParsed = OptimizelyJSON(payload: featureValue)?.toMap()
-                    break
                 }
             }
             
@@ -661,18 +679,18 @@ open class OptimizelyClient: NSObject {
         }
         
         guard let optimizelyJSON = OptimizelyJSON(map: variableMap) else {
-            throw OptimizelyError.invalidDictionary
+            throw OptimizelyError.invalidJSONVariable
         }
         
-        sendDecisionNotification(decisionType: .allFeatureVariables,
-                                 userId: userId,
+        sendDecisionNotification(userId: userId,
                                  attributes: attributes,
-                                 experiment: decision?.experiment,
-                                 variation: decision?.variation,
-                                 source: decision?.source,
-                                 feature: featureFlag,
-                                 featureEnabled: enabled,
-                                 variableValues: variableMap)
+                                 decisionInfo: DecisionInfo(decisionType: .allFeatureVariables,
+                                                            experiment: decision?.experiment,
+                                                            variation: decision?.variation,
+                                                            source: decision?.source,
+                                                            feature: featureFlag,
+                                                            featureEnabled: enabled,
+                                                            variableValues: variableMap))
         return optimizelyJSON
     }
     
@@ -704,8 +722,9 @@ open class OptimizelyClient: NSObject {
     /// - Parameters:
     ///   - eventKey: The event name
     ///   - userId: The user ID associated with the event to track
+    ///   - attributes: The user's attributes.
     ///   - eventTags: A map of event tag names to event tag values (NSString or NSNumber containing float, double, integer, or boolean)
-    /// - Throws: `OptimizelyError` if event parameter is not valid
+    /// - Throws: `OptimizelyError` if error is detected
     public func track(eventKey: String,
                       userId: String,
                       attributes: OptimizelyAttributes? = nil,
@@ -860,98 +879,22 @@ extension OptimizelyClient {
                               async: async)
     }
     
-    func sendDecisionNotification(decisionType: Constants.DecisionType,
-                                  userId: String,
+    func sendDecisionNotification(userId: String,
                                   attributes: OptimizelyAttributes?,
-                                  experiment: Experiment? = nil,
-                                  variation: Variation? = nil,
-                                  source: String? = nil,
-                                  feature: FeatureFlag? = nil,
-                                  featureEnabled: Bool? = nil,
-                                  variableKey: String? = nil,
-                                  variableType: String? = nil,
-                                  variableValue: Any? = nil,
-                                  variableValues: [String: Any]? = nil,
+                                  decisionInfo: DecisionInfo,
                                   async: Bool = true) {
         self.sendNotification(type: .decision,
-                              args: [decisionType.rawValue,
+                              args: [decisionInfo.decisionType.rawValue,
                                      userId,
                                      attributes ?? OptimizelyAttributes(),
-                                     self.makeDecisionInfo(decisionType: decisionType,
-                                                           experiment: experiment,
-                                                           variation: variation,
-                                                           source: source,
-                                                           feature: feature,
-                                                           featureEnabled: featureEnabled,
-                                                           variableKey: variableKey,
-                                                           variableType: variableType,
-                                                           variableValue: variableValue,
-                                                           variableValues: variableValues)],
+                                     decisionInfo.toMap],
                               async: async)
     }
-    
+        
     func sendDatafileChangeNotification(data: Data, async: Bool = true) {
         self.sendNotification(type: .datafileChange, args: [data], async: async)
     }
     
-    func makeDecisionInfo(decisionType: Constants.DecisionType,
-                          experiment: Experiment? = nil,
-                          variation: Variation? = nil,
-                          source: String? = nil,
-                          feature: FeatureFlag? = nil,
-                          featureEnabled: Bool? = nil,
-                          variableKey: String? = nil,
-                          variableType: String? = nil,
-                          variableValue: Any? = nil,
-                          variableValues: [String: Any]? = nil) -> [String: Any] {
-        
-        var decisionInfo = [String: Any]()
-        
-        switch decisionType {
-        case .featureTest, .abTest:
-            guard let experiment = experiment else { return decisionInfo }
-            
-            decisionInfo[Constants.ExperimentDecisionInfoKeys.experiment] = experiment.key
-            decisionInfo[Constants.ExperimentDecisionInfoKeys.variation] = variation?.key ?? NSNull()
-            
-        case .feature, .featureVariable, .allFeatureVariables:
-            guard let feature = feature, let featureEnabled = featureEnabled else { return decisionInfo }
-            
-            decisionInfo[Constants.DecisionInfoKeys.feature] = feature.key
-            decisionInfo[Constants.DecisionInfoKeys.featureEnabled] = featureEnabled
-            
-            let decisionSource: Constants.DecisionSource = experiment != nil ? .featureTest : .rollout
-            decisionInfo[Constants.DecisionInfoKeys.source] = source ?? decisionSource.rawValue
-            
-            
-            var sourceInfo = [String: Any]()
-            if let experiment = experiment, let variation = variation {
-                sourceInfo[Constants.ExperimentDecisionInfoKeys.experiment] = experiment.key
-                sourceInfo[Constants.ExperimentDecisionInfoKeys.variation] = variation.key
-            }
-            decisionInfo[Constants.DecisionInfoKeys.sourceInfo] = sourceInfo
-            
-            // featureVariable
-            
-            if decisionType == .featureVariable {
-                guard let variableKey = variableKey, let variableType = variableType, let variableValue = variableValue else {
-                    return decisionInfo
-                }
-                
-                decisionInfo[Constants.DecisionInfoKeys.variable] = variableKey
-                decisionInfo[Constants.DecisionInfoKeys.variableType] = variableType
-                decisionInfo[Constants.DecisionInfoKeys.variableValue] = variableValue
-            } else if  decisionType == .allFeatureVariables {
-                guard let variableValues = variableValues else {
-                    return decisionInfo
-                }
-                decisionInfo[Constants.DecisionInfoKeys.variableValues] = variableValues
-            }
-        }
-        
-        return decisionInfo
-    }
-    
     func sendNotification(type: NotificationType, args: [Any?], async: Bool = true) {
         let notify = {
             // make sure that notificationCenter is not-nil (still registered when async notification is called)
diff --git a/Sources/Optimizely/OptimizelyError.swift b/Sources/Optimizely/OptimizelyError.swift
index c78984b1f..3fc56ad64 100644
--- a/Sources/Optimizely/OptimizelyError.swift
+++ b/Sources/Optimizely/OptimizelyError.swift
@@ -1,5 +1,5 @@
 /****************************************************************************
-* Copyright 2019-2020, Optimizely, Inc. and contributors                   *
+* Copyright 2019-2021, Optimizely, Inc. and contributors                   *
 *                                                                          *
 * Licensed under the Apache License, Version 2.0 (the "License");          *
 * you may not use this file except in compliance with the License.         *
@@ -18,21 +18,22 @@ import Foundation
 public enum OptimizelyError: Error {
     case generic
 
-    // MARK: - SDK
+    // MARK: - Decision errors
     
     case sdkNotReady
-    
+    case featureKeyInvalid(_ key: String)
+    case variableValueInvalid(_ key: String)
+    case invalidJSONVariable
+
     // MARK: - Experiment
     
     case experimentKeyInvalid(_ key: String)
     case experimentIdInvalid(_ id: String)
     case experimentHasNoTrafficAllocation(_ key: String)
-    case featureKeyInvalid(_ key: String)
     case variationKeyInvalid(_ expKey: String, _ varKey: String)
     case variationIdInvalid(_ expKey: String, _ varKey: String)
     case variationUnknown(_ userId: String, _ key: String)
     case variableKeyInvalid(_ varKey: String, _ feature: String)
-    case variableValueInvalid(_ key: String)
     case eventKeyInvalid(_ key: String)
     case eventBuildFailure(_ key: String)
     case eventTagsFormatInvalid
@@ -77,15 +78,11 @@ public enum OptimizelyError: Error {
     
     case eventDispatchFailed(_ reason: String)
     case eventDispatcherConfigError(_ reason: String)
-    
-    // MARK: - OptimizelyJSON Errors
-    
-    case invalidDictionary
 }
 
 // MARK: - CustomStringConvertible
 
-extension OptimizelyError: CustomStringConvertible {
+extension OptimizelyError: CustomStringConvertible, ReasonProtocol {
     public var description: String {
         return "[Optimizely][Error] " + self.reason
     }
@@ -98,17 +95,20 @@ extension OptimizelyError: CustomStringConvertible {
         var message: String
         
         switch self {
-        case .generic:                                      message = "Unknown reason"
-        case .sdkNotReady:                                  message = "Optimizely SDK not configured properly yet"
+        case .generic:                                      message = "Unknown reason."
+            
+        case .sdkNotReady:                                  message = "Optimizely SDK not configured properly yet."
+        case .featureKeyInvalid(let key):                   message = "No flag was found for key \"\(key)\"."
+        case .variableValueInvalid(let key):                message = "Variable value for key \"\(key)\" is invalid or wrong type."
+        case .invalidJSONVariable:                          message = "Invalid variables for OptimizelyJSON."
+
         case .experimentKeyInvalid(let key):                message = "Experiment key (\(key)) is not in datafile. It is either invalid, paused, or archived."
         case .experimentIdInvalid(let id):                  message = "Experiment ID (\(id)) is not in datafile."
         case .experimentHasNoTrafficAllocation(let key):    message = "No traffic allocation rules are defined for experiement (\(key))."
-        case .featureKeyInvalid(let key):                   message = "Feature key (\(key)) is not in datafile."
         case .variationKeyInvalid(let expKey, let varKey):  message = "No variation key (\(varKey)) defined in datafile for experiment (\(expKey))."
         case .variationIdInvalid(let expKey, let varId):    message = "No variation ID (\(varId)) defined in datafile for experiment (\(expKey))."
         case .variationUnknown(let userId, let key):        message = "User (\(userId)) does not meet conditions to be in experiment/feature (\(key))."
         case .variableKeyInvalid(let varKey, let feature):  message = "Variable with key (\(varKey)) associated with feature with key (\(feature)) is not in datafile."
-        case .variableValueInvalid(let key):                message = "Variable value for key (\(key)) is invalid or wrong type"
         case .eventKeyInvalid(let key):                     message = "Event key (\(key)) is not in datafile."
         case .eventBuildFailure(let key):                   message = "Failed to create a dispatch event (\(key))"
         case .eventTagsFormatInvalid:                       message = "Provided event tags are in an invalid format."
@@ -116,16 +116,16 @@ extension OptimizelyError: CustomStringConvertible {
         case .attributeValueInvalid(let key):               message = "Attribute value for (\(key)) is invalid."
         case .attributeFormatInvalid:                       message = "Provided attributes are in an invalid format."
         case .groupIdInvalid(let id):                       message = "Group ID (\(id)) is not in datafile."
-        case .groupHasNoTrafficAllocation(let id):          message = "No traffic allocation rules are defined for group (\(id))"
-        case .rolloutIdInvalid(let id, let feature):        message = "Invalid rollout ID (\(id)) attached to feature (\(feature))"
+        case .groupHasNoTrafficAllocation(let id):          message = "No traffic allocation rules are defined for group (\(id))."
+        case .rolloutIdInvalid(let id, let feature):        message = "Invalid rollout ID (\(id)) attached to feature (\(feature))."
             
         case .conditionNoMatchingAudience(let id):          message = "Audience (\(id)) is not in datafile."
-        case .conditionInvalidFormat(let hint):             message = "Condition has an invalid format (\(hint))"
-        case .conditionCannotBeEvaluated(let hint):         message = "Condition cannot be evaluated (\(hint))"
+        case .conditionInvalidFormat(let hint):             message = "Condition has an invalid format (\(hint))."
+        case .conditionCannotBeEvaluated(let hint):         message = "Condition cannot be evaluated (\(hint))."
         case .evaluateAttributeInvalidCondition(let condition): message = "Audience condition (\(condition)) has an unsupported condition value. You may need to upgrade to a newer release of the Optimizely SDK."
         case .evaluateAttributeInvalidType(let condition, let value, let key):       message = "Audience condition (\(condition)) evaluated to UNKNOWN because a value of type (\(value)) was passed for user attribute (\(key))."
         case .evaluateAttributeValueOutOfRange(let condition, let key):   message = "Audience condition (\(condition)) evaluated to UNKNOWN because the number value for user attribute (\(key)) is not in the range [-2^53, +2^53]."
-        case .evaluateAttributeInvalidFormat(let hint):     message = "Evaluation attribute has an invalid format (\(hint))"
+        case .evaluateAttributeInvalidFormat(let hint):     message = "Evaluation attribute has an invalid format (\(hint))."
         case .userAttributeInvalidType(let condition):      message = "Audience condition (\(condition)) uses an unknown condition type. You may need to upgrade to a newer release of the Optimizely SDK."
         case .userAttributeInvalidMatch(let condition):     message = "Audience condition (\(condition)) uses an unknown match type. You may need to upgrade to a newer release of the Optimizely SDK."
         case .userAttributeNilValue(let condition):         message = "Audience condition (\(condition)) evaluated to UNKNOWN because of null value."
@@ -133,18 +133,17 @@ extension OptimizelyError: CustomStringConvertible {
         case .nilAttributeValue(let condition, let key):    message = "Audience condition (\(condition)) evaluated to UNKNOWN because a null value was passed for user attribute (\(key))."
         case .missingAttributeValue(let condition, let key):    message = "Audience condition (\(condition)) evaluated to UNKNOWN because no value was passed for user attribute (\(key))."
         case .userIdInvalid:                                message = "Provided user ID is in an invalid format."
-        case .bucketingIdInvalid (let id):                  message = "Invalid bucketing ID (\(id))"
+        case .bucketingIdInvalid (let id):                  message = "Invalid bucketing ID (\(id))."
         case .userProfileInvalid:                           message = "Provided user profile object is invalid."
             
-        case .datafileDownloadFailed(let hint):             message = "Datafile download failed (\(hint))"
+        case .datafileDownloadFailed(let hint):             message = "Datafile download failed (\(hint))."
         case .dataFileInvalid:                              message = "Provided datafile is in an invalid format."
         case .dataFileVersionInvalid (let version):         message = "Provided datafile version (\(version)) is not supported."
-        case .datafileSavingFailed(let hint):               message = "Datafile save failed (\(hint))"
-        case .datafileLoadingFailed(let hint):              message = "Datafile load failed (\(hint))"
+        case .datafileSavingFailed(let hint):               message = "Datafile save failed (\(hint))."
+        case .datafileLoadingFailed(let hint):              message = "Datafile load failed (\(hint))."
             
-        case .eventDispatchFailed(let hint):                message = "Event dispatch failed (\(hint))"
-        case .eventDispatcherConfigError(let hint):         message = "EventDispatcher config error (\(hint))"
-        case .invalidDictionary:                          message = "Unable to initialize OptimizelyJSON with the provided dictionary."
+        case .eventDispatchFailed(let hint):                message = "Event dispatch failed (\(hint))."
+        case .eventDispatcherConfigError(let hint):         message = "EventDispatcher config error (\(hint))."
         }
         
         return message
diff --git a/Sources/Optimizely/OptimizelyJSON+ObjC.swift b/Sources/Optimizely/OptimizelyJSON+ObjC.swift
index e40f2e7d6..b2d93cebf 100644
--- a/Sources/Optimizely/OptimizelyJSON+ObjC.swift
+++ b/Sources/Optimizely/OptimizelyJSON+ObjC.swift
@@ -1,5 +1,5 @@
 /****************************************************************************
-* Copyright 2020, Optimizely, Inc. and contributors                        *
+* Copyright 2020-2021, Optimizely, Inc. and contributors                   *
 *                                                                          *
 * Licensed under the Apache License, Version 2.0 (the "License");          *
 * you may not use this file except in compliance with the License.         *
@@ -30,6 +30,13 @@ extension OptimizelyJSON {
         self.init(map: m)
     }
     
+    @available(swift, obsoleted: 1.0)
+    @objc(isEmpty)
+    /// - Returns: true when one or more variables are included.
+    public func objcIsEmpty() -> Bool {
+        return self.isEmpty
+    }
+
     @available(swift, obsoleted: 1.0)
     @objc(toString)
     /// - Returns: The string representation of json
diff --git a/Sources/Optimizely/OptimizelyJSON.swift b/Sources/Optimizely/OptimizelyJSON.swift
index 7ff6c9cdb..b079beb6e 100644
--- a/Sources/Optimizely/OptimizelyJSON.swift
+++ b/Sources/Optimizely/OptimizelyJSON.swift
@@ -1,5 +1,5 @@
 /****************************************************************************
-* Copyright 2020, Optimizely, Inc. and contributors                        *
+* Copyright 2020-2021, Optimizely, Inc. and contributors                   *
 *                                                                          *
 * Licensed under the Apache License, Version 2.0 (the "License");          *
 * you may not use this file except in compliance with the License.         *
@@ -45,6 +45,14 @@ public class OptimizelyJSON: NSObject {
         self.map = map
     }
     
+    static func createEmpty() -> OptimizelyJSON {
+        return OptimizelyJSON(map: [:])!
+    }
+    
+    public var isEmpty: Bool {
+        return map.isEmpty
+    }
+    
     // MARK: - OptimizelyJSON Implementation
     
     /// - Returns: The string representation of json
@@ -181,3 +189,13 @@ public class OptimizelyJSON: NSObject {
         return nil
     }
 }
+
+extension OptimizelyJSON {
+    
+    // override NSObject Equatable ('==' overriding not working for NSObject)
+    override public func isEqual(_ object: Any?) -> Bool {
+        guard let object = object as? OptimizelyJSON else { return false }
+        return NSDictionary(dictionary: map).isEqual(to: object.toMap())
+    }
+    
+}
diff --git a/Sources/Protocols/OPTBucketer.swift b/Sources/Protocols/OPTBucketer.swift
index 7362889c5..73707982d 100644
--- a/Sources/Protocols/OPTBucketer.swift
+++ b/Sources/Protocols/OPTBucketer.swift
@@ -1,5 +1,5 @@
 /****************************************************************************
-* Copyright 2019-2020, Optimizely, Inc. and contributors                   *
+* Copyright 2019-2021, Optimizely, Inc. and contributors                   *
 *                                                                          *
 * Licensed under the Apache License, Version 2.0 (the "License");          *
 * you may not use this file except in compliance with the License.         *
@@ -23,7 +23,9 @@ protocol OPTBucketer {
      - Parameter bucketingId: Id to be used for bucketing the user.
      - Returns: experiment which represent Experiment.
      */
-    func bucketToExperiment(config: ProjectConfig, group: Group, bucketingId: String) -> Experiment?
+    func bucketToExperiment(config: ProjectConfig,
+                            group: Group,
+                            bucketingId: String) -> DecisionResponse<Experiment>
     
     /**
      Bucket a bucketingId into an experiment.
@@ -31,7 +33,9 @@ protocol OPTBucketer {
      - Parameter bucketingId: The ID to bucket. This must be a non-null, non-empty string.
      - Returns: The variation the bucketingId was bucketed into.
      */
-    func bucketExperiment(config: ProjectConfig, experiment: Experiment, bucketingId: String) -> Variation?
+    func bucketExperiment(config: ProjectConfig,
+                          experiment: Experiment,
+                          bucketingId: String) -> DecisionResponse<Variation>
 
     /**
      Hash the bucketing ID and map it to the range [0, 10000).
diff --git a/Sources/Protocols/OPTDataStore.swift b/Sources/Protocols/OPTDataStore.swift
index 4cb0b911b..7b6b0f1f8 100644
--- a/Sources/Protocols/OPTDataStore.swift
+++ b/Sources/Protocols/OPTDataStore.swift
@@ -1,5 +1,5 @@
 /****************************************************************************
-* Copyright 2019, Optimizely, Inc. and contributors                        *
+* Copyright 2019,2021, Optimizely, Inc. and contributors                   *
 *                                                                          *
 * Licensed under the Apache License, Version 2.0 (the "License");          *
 * you may not use this file except in compliance with the License.         *
@@ -29,5 +29,5 @@ public protocol OPTDataStore {
     func saveItem(forKey: String, value: Any)
     /// removeItem - remove the item to the datastore.
     /// - Parameter forKey: key to save value
-    func removeItem(forKey:String)
+    func removeItem(forKey: String)
 }
diff --git a/Sources/Protocols/OPTDecisionService.swift b/Sources/Protocols/OPTDecisionService.swift
index c20792a8f..dc2273be3 100644
--- a/Sources/Protocols/OPTDecisionService.swift
+++ b/Sources/Protocols/OPTDecisionService.swift
@@ -1,5 +1,5 @@
 /****************************************************************************
-* Copyright 2019-2020, Optimizely, Inc. and contributors                   *
+* Copyright 2019-2021, Optimizely, Inc. and contributors                   *
 *                                                                          *
 * Licensed under the Apache License, Version 2.0 (the "License");          *
 * you may not use this file except in compliance with the License.         *
@@ -31,19 +31,34 @@ protocol OPTDecisionService {
      b. Is the experiment that the user bucketed into NOT mutually excluded?
      c. Does traffic allocation exclude the user?
      
-     - Parameter userId: The ID of the user.
+     - Parameter config: The project configuration.
      - Parameter experiment: The experiment in which to bucket the user.
+     - Parameter userId: The ID of the user.
+     - Parameter attributes: User attributes
+     - Parameter options: An array of decision options
+     - Parameter reasons: A struct to collect decision reasons
      - Returns: The variation assigned to the specified user ID for an experiment.
      */
-    func getVariation(config: ProjectConfig, userId: String, experiment: Experiment, attributes: OptimizelyAttributes) -> Variation?
+    func getVariation(config: ProjectConfig,
+                      experiment: Experiment,
+                      userId: String,
+                      attributes: OptimizelyAttributes,
+                      options: [OptimizelyDecideOption]?) -> DecisionResponse<Variation>
     
     /**
      Get a variation the user is bucketed into for the given FeatureFlag
+     - Parameter config: The project configuration.
      - Parameter featureFlag: The feature flag the user wants to access.
      - Parameter userId: The ID of the user.
      - Parameter attributes: User attributes
+     - Parameter options: An array of decision options
+     - Parameter reasons: A struct to collect decision reasons
      - Returns: The variation assigned to the specified user ID for a feature flag.
      */
-    func getVariationForFeature(config: ProjectConfig, featureFlag: FeatureFlag, userId: String, attributes: OptimizelyAttributes) -> (experiment: Experiment, variation: Variation, source: String)?
+    func getVariationForFeature(config: ProjectConfig,
+                                featureFlag: FeatureFlag,
+                                userId: String,
+                                attributes: OptimizelyAttributes,
+                                options: [OptimizelyDecideOption]?) -> DecisionResponse<FeatureDecision>
     
 }
diff --git a/Sources/Utils/Constants.swift b/Sources/Utils/Constants.swift
index bedb676a6..fd3ec8ba0 100644
--- a/Sources/Utils/Constants.swift
+++ b/Sources/Utils/Constants.swift
@@ -1,5 +1,5 @@
 /****************************************************************************
-* Copyright 2019, Optimizely, Inc. and contributors                        *
+* Copyright 2019-2021, Optimizely, Inc. and contributors                   *
 *                                                                          *
 * Licensed under the Apache License, Version 2.0 (the "License");          *
 * you may not use this file except in compliance with the License.         *
@@ -29,11 +29,11 @@ struct Constants {
     }
     
     enum VariableValueType: String {
-        case string = "string"
-        case integer  = "integer"
-        case double  = "double"
-        case boolean = "boolean"
-        case json = "json"
+        case string
+        case integer
+        case double
+        case boolean
+        case json
     }
     
     enum DecisionType: String {
@@ -42,8 +42,10 @@ struct Constants {
         case featureVariable  = "feature-variable"
         case allFeatureVariables = "all-feature-variables"
         case featureTest = "feature-test"
+        // Decide-APIs
+        case flag = "flag"
     }
-    
+        
     enum DecisionSource: String {
         case experiment = "experiment"
         case featureTest = "feature-test"
@@ -59,6 +61,23 @@ struct Constants {
         static let variableType = "variableType"
         static let variableValue = "variableValue"
         static let variableValues = "variableValues"
+        
+        // Decide-API
+        
+        /// The flag key for which the decision has been made for.
+        static let flagKey = "flagKey"
+        /// The boolean value indicating if the flag is enabled or not.
+        static let enabled = "enabled"
+        /// The collection of variables assocaited with the decision.
+        static let variables = "variables"
+        /// The variation key of the decision. This value will be nil when decision making fails.
+        static let variationKey = "variationKey"
+        /// The rule key of the decision.
+        static let ruleKey = "ruleKey"
+        /// An array of error/info/debug messages describing why the decision has been made.
+        static let reasons = "reasons"
+        /// The boolean value indicating an decision event has been sent for the decision.
+        static let decisionEventDispatched = "decisionEventDispatched"
     }
     
     struct ExperimentDecisionInfoKeys {
diff --git a/Sources/Utils/LogMessage.swift b/Sources/Utils/LogMessage.swift
index fe1d3f123..e88e8dc84 100644
--- a/Sources/Utils/LogMessage.swift
+++ b/Sources/Utils/LogMessage.swift
@@ -1,5 +1,5 @@
 /****************************************************************************
- * Copyright 2019-2020, Optimizely, Inc. and contributors                   *
+ * Copyright 2019-2021, Optimizely, Inc. and contributors                   *
  *                                                                          *
  * Licensed under the Apache License, Version 2.0 (the "License");          *
  * you may not use this file except in compliance with the License.         *
@@ -125,3 +125,9 @@ extension LogMessage: CustomStringConvertible {
         return message
     }
 }
+
+extension LogMessage: ReasonProtocol {
+    var reason: String {
+        return description
+    }
+}
diff --git a/Tests/OptimizelyTests-APIs/OptimizelyClientTests_Decide.swift b/Tests/OptimizelyTests-APIs/OptimizelyClientTests_Decide.swift
new file mode 100644
index 000000000..26d607040
--- /dev/null
+++ b/Tests/OptimizelyTests-APIs/OptimizelyClientTests_Decide.swift
@@ -0,0 +1,76 @@
+/****************************************************************************
+* Copyright 2021, Optimizely, Inc. and contributors                        *
+*                                                                          *
+* Licensed under the Apache License, Version 2.0 (the "License");          *
+* you may not use this file except in compliance with the License.         *
+* You may obtain a copy of the License at                                  *
+*                                                                          *
+*    http://www.apache.org/licenses/LICENSE-2.0                            *
+*                                                                          *
+* Unless required by applicable law or agreed to in writing, software      *
+* distributed under the License is distributed on an "AS IS" BASIS,        *
+* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. *
+* See the License for the specific language governing permissions and      *
+* limitations under the License.                                           *
+***************************************************************************/
+    
+import XCTest
+
+class OptimizelyClientTests_Decide: XCTestCase {
+
+    var optimizely: OptimizelyClient!
+
+    override func setUp() {
+        super.setUp()
+        
+        let datafile = OTUtils.loadJSONDatafile("api_datafile")!
+        optimizely = OptimizelyClient(sdkKey: OTUtils.randomSdkKey)
+        try! optimizely.start(datafile: datafile)
+    }
+   
+    func testCreateUserContext() {
+        let userId = "tester"
+        let attributes: [String: Any] = [
+            "country": "us",
+            "age": 100,
+            "old": true
+        ]
+        
+        let user = optimizely.createUserContext(userId: "tester", attributes: attributes)
+        
+        XCTAssert(user.optimizely == optimizely)
+        XCTAssert(user.userId == userId)
+        XCTAssert(user.attributes["country"] as! String == "us")
+        XCTAssert(user.attributes["age"] as! Int == 100)
+        XCTAssert(user.attributes["old"] as! Bool == true)
+    }
+    
+    func testCreateUserContext_multiple() {
+        let attributes: [String: Any] = [
+            "country": "us",
+            "age": 100,
+            "old": true
+        ]
+        let user1 = optimizely.createUserContext(userId: "tester1", attributes: attributes)
+        let user2 = optimizely.createUserContext(userId: "tester2", attributes: [:])
+        
+        XCTAssert(user1.userId == "tester1")
+        XCTAssert(user2.userId == "tester2")
+    }
+    
+    func testDefaultDecideOptions() {
+        let expOptions: [OptimizelyDecideOption] = [.ignoreUserProfileService,
+                                                    .disableDecisionEvent,
+                                                    .enabledFlagsOnly,
+                                                    .includeReasons]
+        
+        optimizely = OptimizelyClient(sdkKey: OTUtils.randomSdkKey)
+        XCTAssert(optimizely.defaultDecideOptions.count == 0)
+
+        optimizely = OptimizelyClient(sdkKey: OTUtils.randomSdkKey,
+                                      defaultDecideOptions: expOptions)
+        XCTAssert(optimizely.defaultDecideOptions == expOptions)
+    }
+    
+}
+
diff --git a/Tests/OptimizelyTests-APIs/OptimizelyClientTests_OptimizelyJSON.swift b/Tests/OptimizelyTests-APIs/OptimizelyClientTests_OptimizelyJSON.swift
index b4ed8cc49..344280144 100644
--- a/Tests/OptimizelyTests-APIs/OptimizelyClientTests_OptimizelyJSON.swift
+++ b/Tests/OptimizelyTests-APIs/OptimizelyClientTests_OptimizelyJSON.swift
@@ -1,5 +1,5 @@
 /****************************************************************************
- * Copyright 2020, Optimizely, Inc. and contributors                        *
+ * Copyright 2020-2021, Optimizely, Inc. and contributors                   *
  *                                                                          *
  * Licensed under the Apache License, Version 2.0 (the "License");          *
  * you may not use this file except in compliance with the License.         *
@@ -191,6 +191,41 @@ extension OptimizelyClientTests_OptimizelyJSON {
         XCTAssertEqual(optimizelyJSONToString, self.payload)
     }
     
+    func testEqual() {
+        let map1: [String: Any] = [
+            "v1": 1,
+            "v2": "three",
+            "v3": [
+                "v31": 3.0,
+                "v32": ["1","2",3.01,4.23,true]
+            ],
+            "v4": true
+        ]
+        
+        var map2 = map1
+        XCTAssertEqual(OptimizelyJSON(map: map1)!, OptimizelyJSON(map: map2)!)
+        
+        map2 = map1
+        map2["v1"] = 2
+        XCTAssertNotEqual(OptimizelyJSON(map: map1)!, OptimizelyJSON(map: map2)!)
+        
+        map2 = map1
+        map2["v4"] = false
+        XCTAssertNotEqual(OptimizelyJSON(map: map1)!, OptimizelyJSON(map: map2)!)
+
+        map2 = map1
+        map2["v3"] = ["v31": 10.0, "v32": ["1","2",3.01,4.23,true]]
+        XCTAssertNotEqual(OptimizelyJSON(map: map1)!, OptimizelyJSON(map: map2)!)
+
+        map2 = map1
+        map2["v3"] = ["v31": 3.0, "v32": ["1","2",3.01,4.23,false]]
+        XCTAssertNotEqual(OptimizelyJSON(map: map1)!, OptimizelyJSON(map: map2)!)
+
+        map2 = map1
+        map2["v3"] = ["v31": 3.000, "v32": ["1", "2", 3.010, 4.230, true]]
+        XCTAssertEqual(OptimizelyJSON(map: map1)!, OptimizelyJSON(map: map2)!)
+    }
+    
     func testGetValueForInvalidJSONKeyAndEmptyDecodableStruct() {
         let value: EmptyDecodableStruct? = self.optimizelyJSON.getValue(jsonPath: "field4.")
         XCTAssertNil(value)
diff --git a/Tests/OptimizelyTests-Common/BucketTests_BucketVariation.swift b/Tests/OptimizelyTests-Common/BucketTests_BucketVariation.swift
index c78e86b3e..445f7fea7 100644
--- a/Tests/OptimizelyTests-Common/BucketTests_BucketVariation.swift
+++ b/Tests/OptimizelyTests-Common/BucketTests_BucketVariation.swift
@@ -1,5 +1,5 @@
 /****************************************************************************
-* Copyright 2019, Optimizely, Inc. and contributors                        *
+* Copyright 2019,2021, Optimizely, Inc. and contributors                   *
 *                                                                          *
 * Licensed under the Apache License, Version 2.0 (the "License");          *
 * you may not use this file except in compliance with the License.         *
@@ -131,7 +131,7 @@ extension BucketTests_BucketVariation {
                      ["userId": "a very very very very very very very very very very very very very very very long ppd string", "expect": kVariationKeyC]]
 
         for (idx, test) in tests.enumerated() {
-            variation = bucketer.bucketExperiment(config: self.config, experiment: experiment, bucketingId: test["userId"]!)
+            variation = bucketer.bucketExperiment(config: self.config, experiment: experiment, bucketingId: test["userId"]!).result
             XCTAssertEqual(test["expect"], variation?.key, "test[\(idx)] failed")
         }
     }
@@ -149,7 +149,7 @@ extension BucketTests_BucketVariation {
                      ["userId": "a very very very very very very very very very very very very very very very long ppd string", "expect": kVariationKeyC]]
 
         for (idx, test) in tests.enumerated() {
-            variation = bucketer.bucketExperiment(config: self.config, experiment: experiment, bucketingId: test["userId"]!)
+            variation = bucketer.bucketExperiment(config: self.config, experiment: experiment, bucketingId: test["userId"]!).result
             XCTAssertEqual(test["expect"], variation?.key, "test[\(idx)] failed")
         }
     }
@@ -168,7 +168,7 @@ extension BucketTests_BucketVariation {
                      ["userId": "a very very very very very very very very very very very very very very very long ppd string", "expect": kVariationKeyD]]
         
         for test in tests {
-            variation = bucketer.bucketExperiment(config: self.config, experiment: experiment, bucketingId: test["userId"]!)
+            variation = bucketer.bucketExperiment(config: self.config, experiment: experiment, bucketingId: test["userId"]!).result
             XCTAssertNil(variation)
         }
     }
@@ -187,7 +187,7 @@ extension BucketTests_BucketVariation {
                      ["userId": "a very very very very very very very very very very very very very very very long ppd string", "expect": kVariationKeyC]]
 
         for (idx, test) in tests.enumerated() {
-            variation = bucketer.bucketExperiment(config: self.config, experiment: experiment, bucketingId: test["userId"]!)
+            variation = bucketer.bucketExperiment(config: self.config, experiment: experiment, bucketingId: test["userId"]!).result
             XCTAssertEqual(test["expect"], variation?.key, "test[\(idx)] failed")
         }
     }
diff --git a/Tests/OptimizelyTests-Common/BucketTests_ExpToVariation.swift b/Tests/OptimizelyTests-Common/BucketTests_ExpToVariation.swift
index 9ef6c6135..733730ce9 100644
--- a/Tests/OptimizelyTests-Common/BucketTests_ExpToVariation.swift
+++ b/Tests/OptimizelyTests-Common/BucketTests_ExpToVariation.swift
@@ -1,5 +1,5 @@
 /****************************************************************************
-* Copyright 2019, Optimizely, Inc. and contributors                        *
+* Copyright 2019,2021, Optimizely, Inc. and contributors                   *
 *                                                                          *
 * Licensed under the Apache License, Version 2.0 (the "License");          *
 * you may not use this file except in compliance with the License.         *
@@ -116,7 +116,7 @@ extension BucketTests_ExpToVariation {
                      ["userId": "a very very very very very very very very very very very very very very very long ppd string", "expect": kVariationKeyC]]
         
         for (idx, test) in tests.enumerated() {
-            variation = bucketer.bucketToVariation(experiment: experiment, bucketingId: test["userId"]!)
+            variation = bucketer.bucketToVariation(experiment: experiment, bucketingId: test["userId"]!).result
             XCTAssertEqual(test["expect"], variation?.key, "test[\(idx)] failed")
         }
     }
@@ -131,7 +131,7 @@ extension BucketTests_ExpToVariation {
                      ["userId": "a very very very very very very very very very very very very very very very long ppd string"]]
 
         for test in tests {
-            variation = bucketer.bucketToVariation(experiment: experiment, bucketingId: test["userId"]!)
+            variation = bucketer.bucketToVariation(experiment: experiment, bucketingId: test["userId"]!).result
             XCTAssertNil(variation)
         }
     }
@@ -147,7 +147,7 @@ extension BucketTests_ExpToVariation {
                      ["userId": "a very very very very very very very very very very very very very very very long ppd string"]]
 
         for test in tests {
-            variation = bucketer.bucketToVariation(experiment: experiment, bucketingId: test["userId"]!)
+            variation = bucketer.bucketToVariation(experiment: experiment, bucketingId: test["userId"]!).result
             XCTAssertNil(variation)
         }
     }
@@ -165,7 +165,7 @@ extension BucketTests_ExpToVariation {
                      ["userId": "a very very very very very very very very very very very very very very very long ppd string"]]
 
         for test in tests {
-            variation = bucketer.bucketToVariation(experiment: experiment, bucketingId: test["userId"]!)
+            variation = bucketer.bucketToVariation(experiment: experiment, bucketingId: test["userId"]!).result
             XCTAssertNil(variation)
         }
     }
diff --git a/Tests/OptimizelyTests-Common/BucketTests_GroupToExp.swift b/Tests/OptimizelyTests-Common/BucketTests_GroupToExp.swift
index a39c4b145..aff36789c 100644
--- a/Tests/OptimizelyTests-Common/BucketTests_GroupToExp.swift
+++ b/Tests/OptimizelyTests-Common/BucketTests_GroupToExp.swift
@@ -1,5 +1,5 @@
 /****************************************************************************
-* Copyright 2019, Optimizely, Inc. and contributors                        *
+* Copyright 2019-2021, Optimizely, Inc. and contributors                   *
 *                                                                          *
 * Licensed under the Apache License, Version 2.0 (the "License");          *
 * you may not use this file except in compliance with the License.         *
@@ -20,7 +20,7 @@ class BucketTests_GroupToExp: XCTestCase {
 
     var optimizely: OptimizelyClient!
     var config: ProjectConfig!
-    var bucketer: OPTBucketer!
+    var bucketer: DefaultBucketer!
     
     var kUserId = "12345"
     var kGroupId = "333333"
@@ -126,7 +126,7 @@ extension BucketTests_GroupToExp {
         let group = self.config.getGroup(id: kGroupId)
         
         for (idx, test) in tests.enumerated() {
-            let experiment = bucketer.bucketToExperiment(config: self.config, group: group!, bucketingId: test["userId"]!)
+            let experiment = bucketer.bucketToExperiment(config: self.config, group: group!, bucketingId: test["userId"]!).result
             XCTAssertEqual(test["expect"], experiment?.key, "test[\(idx)] failed")
         }
     }
@@ -142,7 +142,7 @@ extension BucketTests_GroupToExp {
                      ["userId": "a very very very very very very very very very very very very very very very long ppd string"]]
         
         for test in tests {
-            let experiment = bucketer.bucketToExperiment(config: self.config, group: group, bucketingId: test["userId"]!)
+            let experiment = bucketer.bucketToExperiment(config: self.config, group: group, bucketingId: test["userId"]!).result
             XCTAssertNil(experiment)
         }
     }
@@ -159,7 +159,7 @@ extension BucketTests_GroupToExp {
                      ["userId": "a very very very very very very very very very very very very very very very long ppd string"]]
         
         for test in tests {
-            let experiment = bucketer.bucketToExperiment(config: self.config, group: group, bucketingId: test["userId"]!)
+            let experiment = bucketer.bucketToExperiment(config: self.config, group: group, bucketingId: test["userId"]!).result
             XCTAssertNil(experiment)
         }
     }
@@ -177,7 +177,7 @@ extension BucketTests_GroupToExp {
                      ["userId": "a very very very very very very very very very very very very very very very long ppd string"]]
         
         for test in tests {
-            let experiment = bucketer.bucketToExperiment(config: self.config, group: group, bucketingId: test["userId"]!)
+            let experiment = bucketer.bucketToExperiment(config: self.config, group: group, bucketingId: test["userId"]!).result
             XCTAssertNil(experiment)
         }
     }
diff --git a/Tests/OptimizelyTests-Common/BucketTests_Others.swift b/Tests/OptimizelyTests-Common/BucketTests_Others.swift
index d07117b61..9170f38c8 100644
--- a/Tests/OptimizelyTests-Common/BucketTests_Others.swift
+++ b/Tests/OptimizelyTests-Common/BucketTests_Others.swift
@@ -1,5 +1,5 @@
 /****************************************************************************
-* Copyright 2019, Optimizely, Inc. and contributors                        *
+* Copyright 2019,2021, Optimizely, Inc. and contributors                   *
 *                                                                          *
 * Licensed under the Apache License, Version 2.0 (the "License");          *
 * you may not use this file except in compliance with the License.         *
@@ -79,7 +79,7 @@ extension BucketTests_Others {
         let group = config?.getGroup(id: groupId)
         
         for test in tests {
-            let experiment = bucketer.bucketToExperiment(config: config!, group: group!, bucketingId: test["userId"]!)
+            let experiment = bucketer.bucketToExperiment(config: config!, group: group!, bucketingId: test["userId"]!).result
             XCTAssertEqual(test["expect"]!, experiment?.key)
         }
     }
@@ -97,7 +97,7 @@ extension BucketTests_Others {
         let group = config?.getGroup(id: groupId)
         
         for test in tests {
-            let experiment = bucketer.bucketToExperiment(config: config!, group: group!, bucketingId: test["userId"]!)
+            let experiment = bucketer.bucketToExperiment(config: config!, group: group!, bucketingId: test["userId"]!).result
             XCTAssertNil(experiment)
         }
     }
@@ -164,7 +164,7 @@ extension BucketTests_Others {
                      ["userId": "a very very very very very very very very very very very very very very very long ppd string", "expect": "Variation_B"]]
 
         for test in tests {
-            let variation = bucketer.bucketToVariation(experiment: experiment, bucketingId: test["userId"]!)!
+            let variation = bucketer.bucketToVariation(experiment: experiment, bucketingId: test["userId"]!).result!
             XCTAssert(variation.key == test["expect"])
         }
     }
@@ -189,7 +189,7 @@ extension BucketTests_Others {
                      ["userId": "a very very very very very very very very very very very very very very very long ppd string", "expect": "null"]]
 
         for test in tests {
-            let experiment = bucketer.bucketToExperiment(config: optimizely.config!, group: group, bucketingId: test["userId"]!)
+            let experiment = bucketer.bucketToExperiment(config: optimizely.config!, group: group, bucketingId: test["userId"]!).result
             let expected = test["expect"]
             if expected != "null" {
                 XCTAssert(experiment!.key == expected)
@@ -216,21 +216,21 @@ extension BucketTests_Others {
 
         for test in tests {
             if test["experiment"] == "experiment1" {
-                var variation = bucketer.bucketExperiment(config: config, experiment: experiment1, bucketingId: test["userId"]!)
+                var variation = bucketer.bucketExperiment(config: config, experiment: experiment1, bucketingId: test["userId"]!).result
                 XCTAssertNotNil(variation)
                 XCTAssert(variation!.key == test["expect"])
-                variation = bucketer.bucketExperiment(config: config, experiment: experiment2, bucketingId: test["userId"]!)
+                variation = bucketer.bucketExperiment(config: config, experiment: experiment2, bucketingId: test["userId"]!).result
                 XCTAssertNil(variation)
             } else if test["experiment"] == "experiment2" {
-                var variation = bucketer.bucketExperiment(config: config, experiment: experiment2, bucketingId: test["userId"]!)
+                var variation = bucketer.bucketExperiment(config: config, experiment: experiment2, bucketingId: test["userId"]!).result
                 XCTAssertNotNil(variation)
                 XCTAssert(variation!.key == test["expect"])
-                variation = bucketer.bucketExperiment(config: config, experiment: experiment1, bucketingId: test["userId"]!)
+                variation = bucketer.bucketExperiment(config: config, experiment: experiment1, bucketingId: test["userId"]!).result
                 XCTAssertNil(variation)
             } else {
-                var variation = bucketer.bucketExperiment(config: config, experiment: experiment1, bucketingId: test["userId"]!)
+                var variation = bucketer.bucketExperiment(config: config, experiment: experiment1, bucketingId: test["userId"]!).result
                 XCTAssertNil(variation)
-                variation = bucketer.bucketExperiment(config: config, experiment: experiment2, bucketingId: test["userId"]!)
+                variation = bucketer.bucketExperiment(config: config, experiment: experiment2, bucketingId: test["userId"]!).result
                 XCTAssertNil(variation)
             }
         }
@@ -243,7 +243,7 @@ extension BucketTests_Others {
 
         let experiment = config.getExperiment(key: "experiment2")!
         XCTAssertNotNil(experiment)
-        let variation = bucketer.bucketExperiment(config: config, experiment: experiment, bucketingId: "user")
+        let variation = bucketer.bucketExperiment(config: config, experiment: experiment, bucketingId: "user").result
         XCTAssertNil(variation)
     }
 
@@ -256,12 +256,12 @@ extension BucketTests_Others {
         XCTAssertNotNil(experiment)
     
         // check testBucketingIdControl is bucketed into "control" variation
-        var variation = bucketer.bucketExperiment(config: config, experiment: experiment, bucketingId: testBucketingIdControl)
+        var variation = bucketer.bucketExperiment(config: config, experiment: experiment, bucketingId: testBucketingIdControl).result
         XCTAssertNotNil(variation)
         XCTAssert(variation!.key == "control", "Unexpected variationKey")
         
         // check testBucketingIdVariation is bucketed into "variation" variation
-        variation = bucketer.bucketExperiment(config: config, experiment: experiment, bucketingId: testBucketingIdVariation)
+        variation = bucketer.bucketExperiment(config: config, experiment: experiment, bucketingId: testBucketingIdVariation).result
         XCTAssertNotNil(variation)
         XCTAssert(variation!.key == "variation", "Unexpected variationKey")
     }
@@ -275,24 +275,24 @@ extension BucketTests_Others {
 
         var experiment = config.getExperiment(key: "group_experiment_2")!
         XCTAssertNotNil(experiment)
-        var variation = bucketer.bucketExperiment(config: config, experiment: experiment, bucketingId: testBucketingIdVariation)
+        var variation = bucketer.bucketExperiment(config: config, experiment: experiment, bucketingId: testBucketingIdVariation).result
         XCTAssertNotNil(variation)
         XCTAssert(variation!.key == "group_exp_2_var_2")
     
         experiment = config.getExperiment(key: "group_experiment_1")!
         XCTAssertNotNil(experiment)
-        variation = bucketer.bucketExperiment(config: config, experiment: experiment, bucketingId: testBucketingIdVariation)
+        variation = bucketer.bucketExperiment(config: config, experiment: experiment, bucketingId: testBucketingIdVariation).result
         XCTAssertNil(variation)
 
         experiment = config.getExperiment(key: "group_experiment_2")!
         XCTAssertNotNil(experiment)
-        variation = bucketer.bucketExperiment(config: config, experiment: experiment, bucketingId: "testUserId")
+        variation = bucketer.bucketExperiment(config: config, experiment: experiment, bucketingId: "testUserId").result
         XCTAssertNotNil(variation)
         XCTAssert(variation!.key == "group_exp_2_var_1")
 
         experiment = config.getExperiment(key: "group_experiment_1")!
         XCTAssertNotNil(experiment)
-        variation = bucketer.bucketExperiment(config: config, experiment: experiment, bucketingId: "testUserId")
+        variation = bucketer.bucketExperiment(config: config, experiment: experiment, bucketingId: "testUserId").result
         XCTAssertNil(variation)
     }
 
diff --git a/Tests/OptimizelyTests-Common/DatafileHandlerTests.swift b/Tests/OptimizelyTests-Common/DatafileHandlerTests.swift
index 3eb86abc6..ce5f85de5 100644
--- a/Tests/OptimizelyTests-Common/DatafileHandlerTests.swift
+++ b/Tests/OptimizelyTests-Common/DatafileHandlerTests.swift
@@ -1,5 +1,5 @@
 /****************************************************************************
-* Copyright 2019, Optimizely, Inc. and contributors                        *
+* Copyright 2019,2021, Optimizely, Inc. and contributors                   *
 *                                                                          *
 * Licensed under the Apache License, Version 2.0 (the "License");          *
 * you may not use this file except in compliance with the License.         *
@@ -507,11 +507,9 @@ class DatafileHandlerTests: XCTestCase {
         }
         
         wait(for: [expectation], timeout: 5.0)
-
     }
     
     func testDownloadWithoutTimeout() {
-
         let handler = TimoutDatafileHandler()
         // create a dummy file at a url to use as or datafile cdn location
         let localUrl = OTUtils.saveAFile(name: "invalidKeyXXXXX", data: "{}".data(using: .utf8)!)
@@ -524,12 +522,11 @@ class DatafileHandlerTests: XCTestCase {
                 print(data ?? "")
                 XCTAssert(true)
                 expectation.fulfill()
-                OTUtils.removeAFile(name: "invalidKeyXXXXX")
+                _ = OTUtils.removeAFile(name: "invalidKeyXXXXX")
             }
         }
 
         wait(for: [expectation], timeout: 10.0)
-        
     }
     
     func testDatafileCacheFormatCompatibilty() {
diff --git a/Tests/OptimizelyTests-Common/DecisionListenerTests.swift b/Tests/OptimizelyTests-Common/DecisionListenerTests.swift
index 31826d7b8..948d03163 100644
--- a/Tests/OptimizelyTests-Common/DecisionListenerTests.swift
+++ b/Tests/OptimizelyTests-Common/DecisionListenerTests.swift
@@ -1,5 +1,5 @@
 /****************************************************************************
- * Copyright 2019-2020, Optimizely, Inc. and contributors                   *
+ * Copyright 2019-2021, Optimizely, Inc. and contributors                   *
  *                                                                          *
  * Licensed under the Apache License, Version 2.0 (the "License");          *
  * you may not use this file except in compliance with the License.         *
@@ -850,6 +850,284 @@ class DecisionListenerTests: XCTestCase {
         _ = self.optimizely.isFeatureEnabled(featureKey: kFeatureKey, userId: kUserId)
         wait(for: [exp], timeout: 1)
     }
+    
+}
+    
+// MARK: - decide apis
+    
+extension DecisionListenerTests {
+    
+    func testDecisionListenerDecideWithUserInExperiment_featureEnabled() {
+        let exp = expectation(description: "x")
+
+        let user = optimizely.createUserContext(userId: kUserId, attributes:["country": "US"])
+        let experiment: Experiment = (self.optimizely.config?.allExperiments.first)!
+        var variation: Variation = (experiment.variations.first)!
+        variation.featureEnabled = true
+        variation.variables?.append(Variable(id: "2696150066", value: "123"))
+        self.optimizely.setDecisionServiceData(experiment: experiment, variation: variation, source: "")
+        
+        notificationCenter.clearAllNotificationListeners()
+        _ = notificationCenter.addDecisionNotificationListener { (type, userId, attributes, decisionInfo) in
+            XCTAssertEqual(type, Constants.DecisionType.flag.rawValue)
+            XCTAssertEqual(userId, user.userId)
+            XCTAssertEqual(attributes!["country"] as! String, "US")
+            
+            XCTAssertEqual(decisionInfo[Constants.DecisionInfoKeys.flagKey] as! String, self.kFeatureKey)
+            XCTAssertEqual(decisionInfo[Constants.DecisionInfoKeys.enabled] as! Bool, true)
+            
+            XCTAssertNotNil(decisionInfo[Constants.DecisionInfoKeys.variables])
+            let variableValues = decisionInfo[Constants.DecisionInfoKeys.variables] as! [String: Any]
+            XCTAssertEqual(variableValues[self.kVariableKeyString] as! String, "123")
+            XCTAssertEqual(variableValues[self.kVariableKeyInt] as! Int, self.kVariableValueInt)
+            XCTAssertEqual(variableValues[self.kVariableKeyDouble] as! Double, self.kVariableValueDouble)
+            XCTAssertEqual(variableValues[self.kVariableKeyBool] as! Bool, self.kVariableValueBool)
+            let jsonMap = (variableValues[self.kVariableKeyJSON] as! [String: Any])
+            XCTAssertEqual(jsonMap["value"] as! Int, 1)
+
+            XCTAssertEqual(decisionInfo[Constants.DecisionInfoKeys.variationKey] as! String, "a")  //exp = "exp_with_audience"
+            XCTAssertEqual(decisionInfo[Constants.DecisionInfoKeys.ruleKey] as! String, "exp_with_audience")
+            XCTAssertNotNil(decisionInfo[Constants.DecisionInfoKeys.reasons])
+            XCTAssertEqual(decisionInfo[Constants.DecisionInfoKeys.decisionEventDispatched] as! Bool, true)
+            exp.fulfill()
+        }
+        
+        _ = user.decide(key: kFeatureKey)
+        wait(for: [exp], timeout: 1)
+    }
+    
+    func testDecisionListenerDecideWithUserInExperiment_featureDisabled() {
+        let exp = expectation(description: "x")
+
+        let user = optimizely.createUserContext(userId: kUserId, attributes:["country": "US"])
+        let experiment: Experiment = (self.optimizely.config?.allExperiments.first)!
+        var variation: Variation = (experiment.variations.first)!
+        variation.featureEnabled = false
+        self.optimizely.setDecisionServiceData(experiment: experiment, variation: variation, source: "")
+        
+        notificationCenter.clearAllNotificationListeners()
+        _ = notificationCenter.addDecisionNotificationListener { (_, _, _, decisionInfo) in
+            XCTAssertEqual(decisionInfo[Constants.DecisionInfoKeys.flagKey] as! String, self.kFeatureKey)
+            XCTAssertEqual(decisionInfo[Constants.DecisionInfoKeys.enabled] as! Bool, false)
+            
+            XCTAssertNotNil(decisionInfo[Constants.DecisionInfoKeys.variables])
+            let variableValues = decisionInfo[Constants.DecisionInfoKeys.variables] as! [String: Any]
+            XCTAssertEqual(variableValues[self.kVariableKeyString] as! String, self.kVariableValueString)
+            XCTAssertEqual(variableValues[self.kVariableKeyInt] as! Int, self.kVariableValueInt)
+            XCTAssertEqual(variableValues[self.kVariableKeyDouble] as! Double, self.kVariableValueDouble)
+            XCTAssertEqual(variableValues[self.kVariableKeyBool] as! Bool, self.kVariableValueBool)
+            let jsonMap = (variableValues[self.kVariableKeyJSON] as! [String: Any])
+            XCTAssertEqual(jsonMap["value"] as! Int, 1)
+
+            XCTAssertEqual(decisionInfo[Constants.DecisionInfoKeys.variationKey] as! String, "a")  //exp = "exp_with_audience"
+            XCTAssertEqual(decisionInfo[Constants.DecisionInfoKeys.ruleKey] as! String, "exp_with_audience")
+            XCTAssertNotNil(decisionInfo[Constants.DecisionInfoKeys.reasons])
+            XCTAssertEqual(decisionInfo[Constants.DecisionInfoKeys.decisionEventDispatched] as! Bool, true)
+            exp.fulfill()
+        }
+        
+        _ = user.decide(key: kFeatureKey)
+        wait(for: [exp], timeout: 1)
+    }
+    
+    func testDecisionListenerDecideWithUserNotInExperimentAndRollout() {
+        let exp = expectation(description: "x")
+        
+        let user = optimizely.createUserContext(userId: kUserId, attributes:["country": "US"])
+
+        self.optimizely.setDecisionServiceData(experiment: nil, variation: nil, source: "")
+        
+        notificationCenter.clearAllNotificationListeners()
+        _ = notificationCenter.addDecisionNotificationListener { (type, userId, attributes, decisionInfo) in
+            XCTAssertEqual(type, Constants.DecisionType.flag.rawValue)
+            XCTAssertEqual(userId, user.userId)
+            XCTAssertEqual(attributes!["country"] as! String, "US")
+
+            XCTAssertEqual(decisionInfo[Constants.DecisionInfoKeys.flagKey] as! String, self.kFeatureKey)
+            XCTAssertEqual(decisionInfo[Constants.DecisionInfoKeys.enabled] as! Bool, false)
+            
+            XCTAssertNotNil(decisionInfo[Constants.DecisionInfoKeys.variables])
+            let variableValues = decisionInfo[Constants.DecisionInfoKeys.variables] as! [String: Any]
+            XCTAssertEqual(variableValues[self.kVariableKeyString] as! String, self.kVariableValueString)
+            XCTAssertEqual(variableValues[self.kVariableKeyInt] as! Int, self.kVariableValueInt)
+            XCTAssertEqual(variableValues[self.kVariableKeyDouble] as! Double, self.kVariableValueDouble)
+            XCTAssertEqual(variableValues[self.kVariableKeyBool] as! Bool, self.kVariableValueBool)
+            let jsonMap = (variableValues[self.kVariableKeyJSON] as! [String: Any])
+            XCTAssertEqual(jsonMap["value"] as! Int, 1)
+
+            XCTAssertNil(decisionInfo[Constants.DecisionInfoKeys.variationKey])
+            XCTAssertNil(decisionInfo[Constants.DecisionInfoKeys.ruleKey])
+            XCTAssertNotNil(decisionInfo[Constants.DecisionInfoKeys.reasons])
+            XCTAssertEqual(decisionInfo[Constants.DecisionInfoKeys.decisionEventDispatched] as! Bool, true)
+            exp.fulfill()
+        }
+        _ = user.decide(key: kFeatureKey)
+
+        wait(for: [exp], timeout: 1)
+    }
+
+    func testDecisionListenerDecide_featureEnabled() {
+        let exp = expectation(description: "x")
+        
+        let user = optimizely.createUserContext(userId: kUserId, attributes:["country": "US"])
+        let experiment: Experiment = (self.optimizely.config?.allExperiments.first)!
+        var variation: Variation = (experiment.variations.first)!
+        variation.featureEnabled = true
+        variation.variables?.append(Variable(id: "2696150066", value: "123"))
+        self.optimizely.setDecisionServiceData(experiment: experiment, variation: variation, source: "")
+        
+        notificationCenter.clearAllNotificationListeners()
+        _ = notificationCenter.addDecisionNotificationListener { (_, _, _, decisionInfo) in
+            XCTAssertEqual(decisionInfo[Constants.DecisionInfoKeys.flagKey] as! String, self.kFeatureKey)
+            XCTAssertEqual(decisionInfo[Constants.DecisionInfoKeys.enabled] as! Bool, true)
+            
+            XCTAssertNotNil(decisionInfo[Constants.DecisionInfoKeys.variables])
+            let variableValues = decisionInfo[Constants.DecisionInfoKeys.variables] as! [String: Any]
+            XCTAssertEqual(variableValues[self.kVariableKeyString] as! String, "123")
+            XCTAssertEqual(variableValues[self.kVariableKeyInt] as! Int, self.kVariableValueInt)
+            XCTAssertEqual(variableValues[self.kVariableKeyDouble] as! Double, self.kVariableValueDouble)
+            XCTAssertEqual(variableValues[self.kVariableKeyBool] as! Bool, self.kVariableValueBool)
+            let jsonMap = (variableValues[self.kVariableKeyJSON] as! [String: Any])
+            XCTAssertEqual(jsonMap["value"] as! Int, 1)
+
+            XCTAssertEqual(decisionInfo[Constants.DecisionInfoKeys.variationKey] as! String, "a")
+            XCTAssertEqual(decisionInfo[Constants.DecisionInfoKeys.ruleKey] as! String, "exp_with_audience")
+            XCTAssertNotNil(decisionInfo[Constants.DecisionInfoKeys.reasons])
+            XCTAssertEqual(decisionInfo[Constants.DecisionInfoKeys.decisionEventDispatched] as! Bool, true)
+            exp.fulfill()
+        }
+        _ = user.decide(key: kFeatureKey)
+        wait(for: [exp], timeout: 1)
+        
+    }
+    
+    func testDecisionListenerDecide_featureDisabled() {
+        let exp = expectation(description: "x")
+        
+        let user = optimizely.createUserContext(userId: kUserId, attributes:["country": "US"])
+        let experiment: Experiment = (self.optimizely.config?.allExperiments.first)!
+        var variation: Variation = (experiment.variations.first)!
+        variation.featureEnabled = false
+        self.optimizely.setDecisionServiceData(experiment: experiment, variation: variation, source: "")
+        
+        notificationCenter.clearAllNotificationListeners()
+        _ = notificationCenter.addDecisionNotificationListener { (_, _, _, decisionInfo) in
+            XCTAssertEqual(decisionInfo[Constants.DecisionInfoKeys.flagKey] as! String, self.kFeatureKey)
+            XCTAssertEqual(decisionInfo[Constants.DecisionInfoKeys.enabled] as! Bool, false)
+            
+            XCTAssertNotNil(decisionInfo[Constants.DecisionInfoKeys.variables])
+            let variableValues = decisionInfo[Constants.DecisionInfoKeys.variables] as! [String: Any]
+            XCTAssertEqual(variableValues[self.kVariableKeyString] as! String, self.kVariableValueString)
+            XCTAssertEqual(variableValues[self.kVariableKeyInt] as! Int, self.kVariableValueInt)
+            XCTAssertEqual(variableValues[self.kVariableKeyDouble] as! Double, self.kVariableValueDouble)
+            XCTAssertEqual(variableValues[self.kVariableKeyBool] as! Bool, self.kVariableValueBool)
+            let jsonMap = (variableValues[self.kVariableKeyJSON] as! [String: Any])
+            XCTAssertEqual(jsonMap["value"] as! Int, 1)
+
+            XCTAssertEqual(decisionInfo[Constants.DecisionInfoKeys.variationKey] as! String, "a")  //exp = "exp_with_audience"
+            XCTAssertEqual(decisionInfo[Constants.DecisionInfoKeys.ruleKey] as! String, "exp_with_audience")
+            XCTAssertNotNil(decisionInfo[Constants.DecisionInfoKeys.reasons])
+            XCTAssertEqual(decisionInfo[Constants.DecisionInfoKeys.decisionEventDispatched] as! Bool, true)
+            exp.fulfill()
+        }
+        _ = user.decide(key: kFeatureKey)
+        wait(for: [exp], timeout: 1)
+    }
+    
+    func testDecisionListenerDecide_disableDecisionEvent() {
+        let user = optimizely.createUserContext(userId: kUserId, attributes:["country": "US"])
+        
+        // (1) default (send-decision-event)
+        
+        var exp = expectation(description: "x")
+
+        let experiment: Experiment = (self.optimizely.config?.allExperiments.first)!
+        let variation: Variation = (experiment.variations.first)!
+        self.optimizely.setDecisionServiceData(experiment: experiment, variation: variation, source: "")
+        
+        notificationCenter.clearAllNotificationListeners()
+        _ = notificationCenter.addDecisionNotificationListener { (type, userId, attributes, decisionInfo) in
+            XCTAssertEqual(decisionInfo[Constants.DecisionInfoKeys.decisionEventDispatched] as! Bool, true)
+            exp.fulfill()
+        }
+        _ = user.decide(key: kFeatureKey)
+        wait(for: [exp], timeout: 1)
+
+        // (2) disable-decision-event)
+
+        exp = expectation(description: "x")
+
+        notificationCenter.clearAllNotificationListeners()
+        _ = notificationCenter.addDecisionNotificationListener { (type, userId, attributes, decisionInfo) in
+            XCTAssertEqual(decisionInfo[Constants.DecisionInfoKeys.decisionEventDispatched] as! Bool, false)
+            exp.fulfill()
+        }
+        _ = user.decide(key: kFeatureKey, options: [.disableDecisionEvent])
+        wait(for: [exp], timeout: 1)
+    }
+
+    func testDecisionListenerDecideWithInvalidType() {
+        let exp = expectation(description: "x")
+        
+        let user = optimizely.createUserContext(userId: kUserId, attributes:["country": "US"])
+
+        for (index, featureFlag) in self.optimizely.config!.project!.featureFlags.enumerated() {
+            if featureFlag.key == kFeatureKey {
+                var flag = featureFlag
+                flag.variables.append(FeatureVariable(id: "2689660112", key: kVariableKeyBool, type: "invalid", subType: nil, defaultValue: "true"))
+                self.optimizely.config?.project.featureFlags[index] = flag
+                break
+            }
+        }
+                
+        notificationCenter.clearAllNotificationListeners()
+        _ = notificationCenter.addDecisionNotificationListener { (_, _, _, decisionInfo) in
+            XCTAssertEqual(decisionInfo[Constants.DecisionInfoKeys.flagKey] as! String, self.kFeatureKey)
+            XCTAssertEqual(decisionInfo[Constants.DecisionInfoKeys.enabled] as! Bool, false)
+            
+            XCTAssertNotNil(decisionInfo[Constants.DecisionInfoKeys.variables])
+            let variableValues = decisionInfo[Constants.DecisionInfoKeys.variables] as! [String: Any]
+            XCTAssertEqual(variableValues[self.kVariableKeyString] as! String, self.kVariableValueString)
+            XCTAssertEqual(variableValues[self.kVariableKeyInt] as! Int, self.kVariableValueInt)
+            XCTAssertEqual(variableValues[self.kVariableKeyDouble] as! Double, self.kVariableValueDouble)
+            XCTAssertEqual(variableValues[self.kVariableKeyBool] as! String, "true")
+            let jsonMap = (variableValues[self.kVariableKeyJSON] as! [String: Any])
+            XCTAssertEqual(jsonMap["value"] as! Int, 1)
+
+            XCTAssertNil(decisionInfo[Constants.DecisionInfoKeys.variationKey])
+            XCTAssertNil(decisionInfo[Constants.DecisionInfoKeys.ruleKey])
+            XCTAssertNotNil(decisionInfo[Constants.DecisionInfoKeys.reasons])
+            XCTAssertEqual(decisionInfo[Constants.DecisionInfoKeys.decisionEventDispatched] as! Bool, true)
+            exp.fulfill()
+        }
+        
+        _ = user.decide(key: kFeatureKey)
+        wait(for: [exp], timeout: 1)
+    }
+    
+    // MARK: - decide-all api
+    
+    func testDecisionListenerDecideAll() {
+        let user = optimizely.createUserContext(userId: kUserId, attributes:["country": "US"])
+
+        var count = 0
+        notificationCenter.clearAllNotificationListeners()
+        _ = notificationCenter.addDecisionNotificationListener { (type, userId, attributes, decisionInfo) in
+            XCTAssertEqual(type, Constants.DecisionType.flag.rawValue)
+            XCTAssertEqual(userId, user.userId)
+            XCTAssertEqual(attributes!["country"] as! String, "US")
+
+            XCTAssertNotNil(decisionInfo[Constants.DecisionInfoKeys.flagKey])
+            XCTAssertNotNil(decisionInfo[Constants.DecisionInfoKeys.enabled])
+            count += 1
+        }
+        
+        _ = user.decideAll()
+        sleep(1)
+        
+        XCTAssertEqual(count, 2)
+    }
+    
 }
 
 class FakeManager: OptimizelyClient {
@@ -864,9 +1142,10 @@ class FakeManager: OptimizelyClient {
                   logger: OPTLogger? = nil,
                   eventDispatcher: OPTEventDispatcher? = nil,
                   userProfileService: OPTUserProfileService? = nil,
-                  defaultLogLevel: OptimizelyLogLevel? = nil) {
+                  defaultLogLevel: OptimizelyLogLevel? = nil,
+                  defaultDecideOptions: [OptimizelyDecideOption]? = nil) {
         
-        super.init(sdkKey: sdkKey, logger: logger, eventDispatcher: eventDispatcher, userProfileService: userProfileService, defaultLogLevel: defaultLogLevel)
+        super.init(sdkKey: sdkKey, logger: logger, eventDispatcher: eventDispatcher, userProfileService: userProfileService, defaultLogLevel: defaultLogLevel, defaultDecideOptions: defaultDecideOptions)
         HandlerRegistryService.shared.removeAll()
         
         let userProfileService = userProfileService ?? DefaultUserProfileService()
@@ -895,11 +1174,17 @@ class FakeDecisionService: DefaultDecisionService {
         super.init(userProfileService: DefaultUserProfileService())
     }
     
-    override func getVariationForFeature(config: ProjectConfig, featureFlag: FeatureFlag, userId: String, attributes: OptimizelyAttributes) -> (experiment: Experiment, variation: Variation, source: String)? {
+    override func getVariationForFeature(config: ProjectConfig,
+                                         featureFlag: FeatureFlag,
+                                         userId: String,
+                                         attributes: OptimizelyAttributes,
+                                         options: [OptimizelyDecideOption]? = nil) -> DecisionResponse<FeatureDecision> {
         guard let experiment = self.experiment, let tmpVariation = self.variation else {
-            return nil
+            return DecisionResponse.nilNoReasons()
         }
-        return (experiment, tmpVariation, self.source)
+        
+        let featureDecision = FeatureDecision(experiment: experiment, variation: tmpVariation, source: source)
+        return DecisionResponse.responseNoReasons(result: featureDecision)
     }
 }
 
diff --git a/Tests/OptimizelyTests-Common/DecisionServiceTests.swift b/Tests/OptimizelyTests-Common/DecisionServiceTests.swift
index bee5ba23a..c9939ce7f 100644
--- a/Tests/OptimizelyTests-Common/DecisionServiceTests.swift
+++ b/Tests/OptimizelyTests-Common/DecisionServiceTests.swift
@@ -1,5 +1,5 @@
 /****************************************************************************
-* Copyright 2019, Optimizely, Inc. and contributors                        *
+* Copyright 2019,2021, Optimizely, Inc. and contributors                   *
 *                                                                          *
 * Licensed under the Apache License, Version 2.0 (the "License");          *
 * you may not use this file except in compliance with the License.         *
@@ -37,7 +37,7 @@ class DecisionServiceTests: XCTestCase {
         
         let experiment = config.project.experiments.filter({$0.key == "typed_audience_experiment"}).first
         let attr = ["integerKey": 1, "doubleKey": 99.0, "booleanKey": true, "nationality": "English"] as [String: Any]
-        let variation = decisionService.getVariation(config: config, userId: "1234", experiment: experiment!, attributes: attr)
+        let variation = decisionService.getVariation(config: config, experiment: experiment!, userId: "1234", attributes: attr)
         
         XCTAssertNotNil(variation)
         
diff --git a/Tests/OptimizelyTests-Common/DecisionServiceTests_Experiments.swift b/Tests/OptimizelyTests-Common/DecisionServiceTests_Experiments.swift
index a84180dee..0a0d0c239 100644
--- a/Tests/OptimizelyTests-Common/DecisionServiceTests_Experiments.swift
+++ b/Tests/OptimizelyTests-Common/DecisionServiceTests_Experiments.swift
@@ -1,5 +1,5 @@
 /****************************************************************************
-* Copyright 2019-2020, Optimizely, Inc. and contributors                   *
+* Copyright 2019-2021, Optimizely, Inc. and contributors                   *
 *                                                                          *
 * Licensed under the Apache License, Version 2.0 (the "License");          *
 * you may not use this file except in compliance with the License.         *
@@ -242,9 +242,9 @@ extension DecisionServiceTests_Experiments {
         // (0) initial - no variation mapped for invalid audience id
         
         variation = self.decisionService.getVariation(config: config,
-                                                      userId: kUserId,
                                                       experiment: experiment,
-                                                      attributes: kAttributesCountryMatch)
+                                                      userId: kUserId,
+                                                      attributes: kAttributesCountryMatch).result
         XCTAssertNil(variation, "no matching audience should return nil")
         
         // (1) non-running experiement should return nil
@@ -253,9 +253,9 @@ extension DecisionServiceTests_Experiments {
         self.config.project.experiments = [experiment]
         
         variation = self.decisionService.getVariation(config: config,
-                                                      userId: kUserId,
                                                       experiment: experiment,
-                                                      attributes: kAttributesCountryMatch)
+                                                      userId: kUserId,
+                                                      attributes: kAttributesCountryMatch).result
         XCTAssertNil(variation, "not running experiments return nil")
         
         // recover to running state for following tests
@@ -275,9 +275,9 @@ extension DecisionServiceTests_Experiments {
         
         // local forcedVariation wins
         variation = self.decisionService.getVariation(config: config,
-                                                      userId: kUserId,
                                                       experiment: experiment,
-                                                      attributes: kAttributesCountryMatch)
+                                                      userId: kUserId,
+                                                      attributes: kAttributesCountryMatch).result
         XCTAssert(variation!.key == kVariationKeyA, "local forcedVariation should override")
         
         // (3) remote whitelisting overrides
@@ -289,9 +289,9 @@ extension DecisionServiceTests_Experiments {
         
         // no local variation, so now remote variation works
         variation = self.decisionService.getVariation(config: config,
-                                                      userId: kUserId,
                                                       experiment: experiment,
-                                                      attributes: kAttributesCountryMatch)
+                                                      userId: kUserId,
+                                                      attributes: kAttributesCountryMatch).result
         XCTAssert(variation!.key == kVariationKeyB, "remote forcedVariation should override")
         
         // reset remote forcedVariations as well
@@ -306,9 +306,9 @@ extension DecisionServiceTests_Experiments {
         
         // no variation mapped for invalid audience id
         variation = self.decisionService.getVariation(config: config,
-                                                      userId: kUserId,
                                                       experiment: experiment,
-                                                      attributes: kAttributesCountryMatch)
+                                                      userId: kUserId,
+                                                      attributes: kAttributesCountryMatch).result
         XCTAssertNil(variation, "no matching audience should return nil")
         
     }
@@ -322,9 +322,9 @@ extension DecisionServiceTests_Experiments {
         // (0) no forcedVariation + no UserProfileService (reset), no attributes -> decision returns nil
         
         variation = self.decisionService.getVariation(config: config,
-                                                      userId: kUserId,
                                                       experiment: experiment,
-                                                      attributes: kAttributesEmpty)
+                                                      userId: kUserId,
+                                                      attributes: kAttributesEmpty).result
         XCTAssertNil(variation, "bucketing should return nil")
         
         // (1) desicion + bucketing
@@ -332,9 +332,9 @@ extension DecisionServiceTests_Experiments {
         // no forced variations + no UserProfileService, so local decision + bucketing should return valid variation
         
         variation = self.decisionService.getVariation(config: config,
-                                                      userId: kUserId,
                                                       experiment: experiment,
-                                                      attributes: kAttributesCountryMatch)
+                                                      userId: kUserId,
+                                                      attributes: kAttributesCountryMatch).result
         XCTAssert(variation!.key == kVariationKeyD, "bucketing should work")
         
         // (2) UserProfileService updated by previous decisions
@@ -342,9 +342,9 @@ extension DecisionServiceTests_Experiments {
         // no attributes, but UserProfile data by (1) will return valid variatin
         
         variation = self.decisionService.getVariation(config: config,
-                                                      userId: kUserId,
                                                       experiment: experiment,
-                                                      attributes: kAttributesEmpty)
+                                                      userId: kUserId,
+                                                      attributes: kAttributesEmpty).result
         XCTAssert(variation!.key == kVariationKeyD, "bucketing should work")
     }
     
@@ -360,9 +360,9 @@ extension DecisionServiceTests_Experiments {
         
         // no local variation, so now remote variation works
         variation = self.decisionService.getVariation(config: config,
-                                                      userId: kUserId,
                                                       experiment: experiment,
-                                                      attributes: kAttributesCountryMatch)
+                                                      userId: kUserId,
+                                                      attributes: kAttributesCountryMatch).result
         XCTAssert(variation!.key == kVariationKeyD, "invalid forced variation should be skipped")
     }
     
@@ -385,21 +385,21 @@ extension DecisionServiceTests_Experiments {
         result = self.decisionService.doesMeetAudienceConditions(config: config,
                                                                  experiment: experiment,
                                                                  userId: kUserId,
-                                                                 attributes: kAttributesCountryMatch)
+                                                                 attributes: kAttributesCountryMatch).result
         XCTAssert(result, "attribute should be matched to audienceConditions")
         
         // (2) matching false
         result = self.decisionService.doesMeetAudienceConditions(config: config,
                                                                  experiment: experiment,
                                                                  userId: kUserId,
-                                                                 attributes: kAttributesCountryNotMatch)
+                                                                 attributes: kAttributesCountryNotMatch).result
         XCTAssertFalse(result, "attribute should be matched to audienceConditions")
         
         // (3) other attribute
         result = self.decisionService.doesMeetAudienceConditions(config: config,
                                                                  experiment: experiment,
                                                                  userId: kUserId,
-                                                                 attributes: kAttributesAgeMatch)
+                                                                 attributes: kAttributesAgeMatch).result
         XCTAssertFalse(result, "no matching attribute provided")
     }
     
@@ -416,21 +416,21 @@ extension DecisionServiceTests_Experiments {
         result = self.decisionService.doesMeetAudienceConditions(config: config,
                                                                  experiment: experiment,
                                                                  userId: kUserId,
-                                                                 attributes: kAttributesCountryMatch)
+                                                                 attributes: kAttributesCountryMatch).result
         XCTAssert(result, "attribute should be matched to audienceConditions")
         
         // (2) matching false
         result = self.decisionService.doesMeetAudienceConditions(config: config,
                                                                  experiment: experiment,
                                                                  userId: kUserId,
-                                                                 attributes: kAttributesCountryNotMatch)
+                                                                 attributes: kAttributesCountryNotMatch).result
         XCTAssertFalse(result, "attribute should be matched to audienceConditions")
         
         // (3) other attribute
         result = self.decisionService.doesMeetAudienceConditions(config: config,
                                                                  experiment: experiment,
                                                                  userId: kUserId,
-                                                                 attributes: kAttributesAgeMatch)
+                                                                 attributes: kAttributesAgeMatch).result
         XCTAssertFalse(result, "no matching attribute provided")
     }
     
@@ -444,7 +444,7 @@ extension DecisionServiceTests_Experiments {
         result = self.decisionService.doesMeetAudienceConditions(config: config,
                                                                  experiment: experiment,
                                                                  userId: kUserId,
-                                                                 attributes: kAttributesCountryMatch)
+                                                                 attributes: kAttributesCountryMatch).result
         XCTAssert(result, "empty conditions is true always")
     }
     
@@ -458,7 +458,7 @@ extension DecisionServiceTests_Experiments {
         result = self.decisionService.doesMeetAudienceConditions(config: config,
                                                                  experiment: experiment,
                                                                  userId: kUserId,
-                                                                 attributes: kAttributesCountryMatch)
+                                                                 attributes: kAttributesCountryMatch).result
         XCTAssert(result, "empty conditions is true always")
     }
     
@@ -477,13 +477,13 @@ extension DecisionServiceTests_Experiments {
         result = self.decisionService.doesMeetAudienceConditions(config: config,
                                                                  experiment: experiment,
                                                                  userId: kUserId,
-                                                                 attributes: kAttributesCountryMatch)
+                                                                 attributes: kAttributesCountryMatch).result
         XCTAssert(result)
         
         result = self.decisionService.doesMeetAudienceConditions(config: config,
                                                                  experiment: experiment,
                                                                  userId: kUserId,
-                                                                 attributes: kAttributesEmpty)
+                                                                 attributes: kAttributesEmpty).result
         XCTAssertFalse(result)
         
         // (2) invalid string in "audienceConditions"
@@ -494,7 +494,7 @@ extension DecisionServiceTests_Experiments {
         result = self.decisionService.doesMeetAudienceConditions(config: config,
                                                                  experiment: experiment,
                                                                  userId: kUserId,
-                                                                 attributes: kAttributesCountryMatch)
+                                                                 attributes: kAttributesCountryMatch).result
         XCTAssert(result)
         
         // (2) invalid string in "audienceConditions"
@@ -505,7 +505,7 @@ extension DecisionServiceTests_Experiments {
         result = self.decisionService.doesMeetAudienceConditions(config: config,
                                                                  experiment: experiment,
                                                                  userId: kUserId,
-                                                                 attributes: kAttributesCountryMatch)
+                                                                 attributes: kAttributesCountryMatch).result
         XCTAssert(result)
     }
     
@@ -526,7 +526,7 @@ extension DecisionServiceTests_Experiments {
         result = self.decisionService.doesMeetAudienceConditions(config: config,
                                                                  experiment: experiment,
                                                                  userId: kUserId,
-                                                                 attributes: kAttributesAgeMatch)
+                                                                 attributes: kAttributesAgeMatch).result
         
         XCTAssert(MockLogger.logFound)
         XCTAssertFalse(result)
@@ -543,7 +543,7 @@ extension DecisionServiceTests_Experiments {
         result = self.decisionService.doesMeetAudienceConditions(config: config,
                                                                  experiment: experiment,
                                                                  userId: kUserId,
-                                                                 attributes: kAttributesAgeMatch)
+                                                                 attributes: kAttributesAgeMatch).result
         
         XCTAssert(MockLogger.logFound)
         XCTAssertFalse(result)
@@ -560,7 +560,7 @@ extension DecisionServiceTests_Experiments {
         result = self.decisionService.doesMeetAudienceConditions(config: config,
                                                                  experiment: experiment,
                                                                  userId: kUserId,
-                                                                 attributes: kAttributesAgeMatch)
+                                                                 attributes: kAttributesAgeMatch).result
         
         XCTAssert(MockLogger.logFound)
         XCTAssertFalse(result)
@@ -577,7 +577,7 @@ extension DecisionServiceTests_Experiments {
         result = self.decisionService.doesMeetAudienceConditions(config: config,
                                                                  experiment: experiment,
                                                                  userId: kUserId,
-                                                                 attributes: kAttributesCountryMatch)
+                                                                 attributes: kAttributesCountryMatch).result
         
         XCTAssert(MockLogger.logFound)
         XCTAssertFalse(result)
@@ -594,7 +594,7 @@ extension DecisionServiceTests_Experiments {
         result = self.decisionService.doesMeetAudienceConditions(config: config,
                                                                  experiment: experiment,
                                                                  userId: kUserId,
-                                                                 attributes: kAttributesAgeMatch)
+                                                                 attributes: kAttributesAgeMatch).result
         
         XCTAssert(MockLogger.logFound)
         XCTAssertFalse(result)
@@ -611,7 +611,7 @@ extension DecisionServiceTests_Experiments {
         result = self.decisionService.doesMeetAudienceConditions(config: config,
                                                                  experiment: experiment,
                                                                  userId: kUserId,
-                                                                 attributes: ["age": nil])
+                                                                 attributes: ["age": nil]).result
         
         XCTAssert(MockLogger.logFound)
         XCTAssertFalse(result)
@@ -628,7 +628,7 @@ extension DecisionServiceTests_Experiments {
         result = self.decisionService.doesMeetAudienceConditions(config: config,
                                                                  experiment: experiment,
                                                                  userId: kUserId,
-                                                                 attributes: kAttributesAgeMatch)
+                                                                 attributes: kAttributesAgeMatch).result
         
         XCTAssert(MockLogger.logFound)
         XCTAssertFalse(result)
@@ -645,7 +645,7 @@ extension DecisionServiceTests_Experiments {
         result = self.decisionService.doesMeetAudienceConditions(config: config,
                                                                  experiment: experiment,
                                                                  userId: kUserId,
-                                                                 attributes: ["country": ["invalid"]])
+                                                                 attributes: ["country": ["invalid"]]).result
         
         XCTAssert(MockLogger.logFound)
         XCTAssertFalse(result)
@@ -662,7 +662,7 @@ extension DecisionServiceTests_Experiments {
         result = self.decisionService.doesMeetAudienceConditions(config: config,
                                                                  experiment: experiment,
                                                                  userId: kUserId,
-                                                                 attributes: ["age": Double.infinity])
+                                                                 attributes: ["age": Double.infinity]).result
         
         XCTAssert(MockLogger.logFound)
         XCTAssertFalse(result)
@@ -679,7 +679,7 @@ extension DecisionServiceTests_Experiments {
         result = self.decisionService.doesMeetAudienceConditions(config: config,
                                                                  experiment: experiment,
                                                                  userId: kUserId,
-                                                                 attributes: kAttributesAgeMatch)
+                                                                 attributes: kAttributesAgeMatch).result
         
         XCTAssert(MockLogger.logFound)
         XCTAssertFalse(result)
@@ -696,7 +696,7 @@ extension DecisionServiceTests_Experiments {
         result = self.decisionService.doesMeetAudienceConditions(config: config,
                                                                  experiment: experiment,
                                                                  userId: kUserId,
-                                                                 attributes: ["age": ["invalid"]])
+                                                                 attributes: ["age": ["invalid"]]).result
         
         XCTAssert(MockLogger.logFound)
         XCTAssertFalse(result)
@@ -713,7 +713,7 @@ extension DecisionServiceTests_Experiments {
         result = self.decisionService.doesMeetAudienceConditions(config: config,
                                                                  experiment: experiment,
                                                                  userId: kUserId,
-                                                                 attributes: kAttributesAgeMatch)
+                                                                 attributes: kAttributesAgeMatch).result
         
         XCTAssert(MockLogger.logFound)
         XCTAssertFalse(result)
@@ -730,7 +730,7 @@ extension DecisionServiceTests_Experiments {
         result = self.decisionService.doesMeetAudienceConditions(config: config,
                                                                  experiment: experiment,
                                                                  userId: kUserId,
-                                                                 attributes: ["age": ["invalid"]])
+                                                                 attributes: ["age": ["invalid"]]).result
         
         XCTAssert(MockLogger.logFound)
         XCTAssertFalse(result)
@@ -747,7 +747,7 @@ extension DecisionServiceTests_Experiments {
         result = self.decisionService.doesMeetAudienceConditions(config: config,
                                                                  experiment: experiment,
                                                                  userId: kUserId,
-                                                                 attributes: kAttributesAgeMatch)
+                                                                 attributes: kAttributesAgeMatch).result
         
         XCTAssert(MockLogger.logFound)
         XCTAssertFalse(result)
@@ -764,7 +764,7 @@ extension DecisionServiceTests_Experiments {
         result = self.decisionService.doesMeetAudienceConditions(config: config,
                                                                  experiment: experiment,
                                                                  userId: kUserId,
-                                                                 attributes: ["age": ["invalid"]])
+                                                                 attributes: ["age": ["invalid"]]).result
         
         XCTAssert(MockLogger.logFound)
         XCTAssertFalse(result)
diff --git a/Tests/OptimizelyTests-Common/DecisionServiceTests_Features.swift b/Tests/OptimizelyTests-Common/DecisionServiceTests_Features.swift
index aae83c8b4..fe1d338df 100644
--- a/Tests/OptimizelyTests-Common/DecisionServiceTests_Features.swift
+++ b/Tests/OptimizelyTests-Common/DecisionServiceTests_Features.swift
@@ -1,5 +1,5 @@
 /****************************************************************************
-* Copyright 2019-2020, Optimizely, Inc. and contributors                   *
+* Copyright 2019-2021, Optimizely, Inc. and contributors                   *
 *                                                                          *
 * Licensed under the Apache License, Version 2.0 (the "License");          *
 * you may not use this file except in compliance with the License.         *
@@ -261,7 +261,7 @@ extension DecisionServiceTests_Features {
         let pair = self.decisionService.getVariationForFeatureExperiment(config: config,
                                                                          featureFlag: featureFlag,
                                                                          userId: kUserId,
-                                                                         attributes: kAttributesCountryMatch)
+                                                                         attributes: kAttributesCountryMatch).result
         XCTAssert(pair!.experiment.key == kExperimentKey)
         XCTAssert(pair!.variation.key == kVariationKeyD)
         XCTAssert(pair!.source == Constants.DecisionSource.featureTest.rawValue)
@@ -271,7 +271,7 @@ extension DecisionServiceTests_Features {
         let pair = self.decisionService.getVariationForFeatureExperiment(config: config,
                                                                          featureFlag: featureFlag,
                                                                          userId: kUserId,
-                                                                         attributes: kAttributesCountryNotMatch)
+                                                                         attributes: kAttributesCountryNotMatch).result
         XCTAssertNil(pair)
     }
     
@@ -283,7 +283,7 @@ extension DecisionServiceTests_Features {
         let pair = self.decisionService.getVariationForFeatureExperiment(config: config,
                                                                          featureFlag: featureFlag,
                                                                          userId: kUserId,
-                                                                         attributes: kAttributesCountryMatch)
+                                                                         attributes: kAttributesCountryMatch).result
         XCTAssertNil(pair)
     }
     
@@ -303,7 +303,7 @@ extension DecisionServiceTests_Features {
         let pair = self.decisionService.getVariationForFeatureRollout(config: config,
                                                                            featureFlag: featureFlag,
                                                                            userId: kUserId,
-                                                                           attributes: kAttributesRolloutAge1Match)
+                                                                           attributes: kAttributesRolloutAge1Match).result
         
         XCTAssert(pair?.experiment.id == kRolloutExperimentId)
         XCTAssert(pair?.variation.key == kRolloutVariationKeyA)
@@ -314,7 +314,7 @@ extension DecisionServiceTests_Features {
         let variation = self.decisionService.getVariationForFeatureRollout(config: config,
                                                                            featureFlag: featureFlag,
                                                                            userId: kUserId,
-                                                                           attributes: kAttributesEmpty)
+                                                                           attributes: kAttributesEmpty).result
         XCTAssertNil(variation)
     }
     
@@ -327,7 +327,7 @@ extension DecisionServiceTests_Features {
         let variation = self.decisionService.getVariationForFeatureRollout(config: config,
                                                                            featureFlag: featureFlag,
                                                                            userId: kUserId,
-                                                                           attributes: kAttributesEmpty)
+                                                                           attributes: kAttributesEmpty).result
         XCTAssertNil(variation)
     }
     
@@ -341,7 +341,7 @@ extension DecisionServiceTests_Features {
         let variation = self.decisionService.getVariationForFeatureRollout(config: config,
                                                                            featureFlag: featureFlag,
                                                                            userId: kUserId,
-                                                                           attributes: kAttributesRolloutAge1Match)
+                                                                           attributes: kAttributesRolloutAge1Match).result
         XCTAssertNil(variation)
     }
     
@@ -355,7 +355,7 @@ extension DecisionServiceTests_Features {
         let pair = self.decisionService.getVariationForFeatureRollout(config: config,
                                                                            featureFlag: featureFlag,
                                                                            userId: kUserId,
-                                                                           attributes: kAttributesRolloutAge1Match)
+                                                                           attributes: kAttributesRolloutAge1Match).result
         XCTAssert(pair?.experiment.id == kRolloutExperimentId3)
         XCTAssert(pair?.variation.key == kRolloutVariationKeyC)
         XCTAssert(pair?.source == Constants.DecisionSource.rollout.rawValue)
@@ -370,7 +370,7 @@ extension DecisionServiceTests_Features {
         let pair = self.decisionService.getVariationForFeatureRollout(config: config,
                                                                            featureFlag: featureFlag,
                                                                            userId: kUserId,
-                                                                           attributes: kAttributesRolloutAge2Match)
+                                                                           attributes: kAttributesRolloutAge2Match).result
         XCTAssert(pair?.experiment.id == kRolloutExperimentId2)
         XCTAssert(pair?.variation.key == kRolloutVariationKeyB)
         XCTAssert(pair?.source == Constants.DecisionSource.rollout.rawValue)
@@ -386,7 +386,7 @@ extension DecisionServiceTests_Features {
         let pair = self.decisionService.getVariationForFeatureRollout(config: config,
                                                                            featureFlag: featureFlag,
                                                                            userId: kUserId,
-                                                                           attributes: kAttributesRolloutAge1Match)
+                                                                           attributes: kAttributesRolloutAge1Match).result
         XCTAssert(pair?.experiment.id == kRolloutExperimentId)
         XCTAssert(pair?.variation.key == kRolloutVariationKeyA)
         XCTAssert(pair?.source == Constants.DecisionSource.rollout.rawValue)
@@ -404,7 +404,7 @@ extension DecisionServiceTests_Features {
         let pair = self.decisionService.getVariationForFeatureRollout(config: config,
                                                                            featureFlag: featureFlag,
                                                                            userId: kUserId,
-                                                                           attributes: kAttributesRolloutAge2Match)
+                                                                           attributes: kAttributesRolloutAge2Match).result
         XCTAssertNil(pair)
     }
     
@@ -419,7 +419,7 @@ extension DecisionServiceTests_Features {
         let pair = self.decisionService.getVariationForFeatureRollout(config: config,
                                                                            featureFlag: featureFlag,
                                                                            userId: kUserId,
-                                                                           attributes: kAttributesRolloutAge1Match)
+                                                                           attributes: kAttributesRolloutAge1Match).result
         XCTAssertNil(pair?.variation)
     }
 }
@@ -432,7 +432,7 @@ extension DecisionServiceTests_Features {
         let pair = self.decisionService.getVariationForFeature(config: config,
                                                                featureFlag: featureFlag,
                                                                userId: kUserId,
-                                                               attributes: kAttributesCountryMatch)
+                                                               attributes: kAttributesCountryMatch).result
         XCTAssertNotNil(pair)
         XCTAssert(pair!.experiment.key == kExperimentKey)
         XCTAssert(pair!.variation.key == kVariationKeyD)
@@ -442,7 +442,7 @@ extension DecisionServiceTests_Features {
         let pair = self.decisionService.getVariationForFeature(config: config,
                                                                featureFlag: featureFlag,
                                                                userId: kUserId,
-                                                               attributes: kAttributesCountryNotMatch)
+                                                               attributes: kAttributesCountryNotMatch).result
         XCTAssertNil(pair)
     }
     
@@ -455,7 +455,7 @@ extension DecisionServiceTests_Features {
         let pair = self.decisionService.getVariationForFeature(config: config,
                                                                featureFlag: featureFlag,
                                                                userId: kUserId,
-                                                               attributes: kAttributesCountryNotMatch)
+                                                               attributes: kAttributesCountryNotMatch).result
         XCTAssertNotNil(pair)
         XCTAssert(pair!.experiment.id == kRolloutExperimentId3)
         XCTAssert(pair!.variation.key == kRolloutVariationKeyC)
diff --git a/Tests/OptimizelyTests-Common/DecisionServiceTests_Others.swift b/Tests/OptimizelyTests-Common/DecisionServiceTests_Others.swift
index cf4e0bfaf..a7a617029 100644
--- a/Tests/OptimizelyTests-Common/DecisionServiceTests_Others.swift
+++ b/Tests/OptimizelyTests-Common/DecisionServiceTests_Others.swift
@@ -1,18 +1,18 @@
 /****************************************************************************
-* Copyright 2019-2020, Optimizely, Inc. and contributors                   *
-*                                                                          *
-* Licensed under the Apache License, Version 2.0 (the "License");          *
-* you may not use this file except in compliance with the License.         *
-* You may obtain a copy of the License at                                  *
-*                                                                          *
-*    http://www.apache.org/licenses/LICENSE-2.0                            *
-*                                                                          *
-* Unless required by applicable law or agreed to in writing, software      *
-* distributed under the License is distributed on an "AS IS" BASIS,        *
-* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. *
-* See the License for the specific language governing permissions and      *
-* limitations under the License.                                           *
-***************************************************************************/
+ * Copyright 2019-2021, Optimizely, Inc. and contributors                   *
+ *                                                                          *
+ * Licensed under the Apache License, Version 2.0 (the "License");          *
+ * you may not use this file except in compliance with the License.         *
+ * You may obtain a copy of the License at                                  *
+ *                                                                          *
+ *    http://www.apache.org/licenses/LICENSE-2.0                            *
+ *                                                                          *
+ * Unless required by applicable law or agreed to in writing, software      *
+ * distributed under the License is distributed on an "AS IS" BASIS,        *
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. *
+ * See the License for the specific language governing permissions and      *
+ * limitations under the License.                                           *
+ ***************************************************************************/
 
 import XCTest
 
@@ -20,26 +20,27 @@ class DecisionServiceTests_Others: XCTestCase {
     
     let ktypeAudienceDatafileName = "typed_audience_datafile"
     let kExperimentWithTypedAudienceKey = "audience_combinations_experiment"
-
+    
     let kUserId = "6369992312"
     let kAttributeKey = "browser_type"
     let kAttributeValue = "firefox"
-
+    
     func testDoesMeetAudienceConditionsWithValidAudienceIdAndEmptyAudienceConditions() {
         let optimizely = OTUtils.createOptimizely(datafileName: ktypeAudienceDatafileName, clearUserProfileService: true)!
         let config = optimizely.config!
         
         let attributes = [kAttributeKey: kAttributeValue]
-
+        
         var experiment = optimizely.config!.getExperiment(key: kExperimentWithTypedAudienceKey)!
         experiment.audienceConditions = ConditionHolder.array([])
-        let isValid = (optimizely.decisionService as! DefaultDecisionService).doesMeetAudienceConditions(config: config,
-                                                                                                         experiment: experiment,
-                                                                                                         userId: kUserId,
-                                                                                                         attributes: attributes)
+        let isValid = (optimizely.decisionService as! DefaultDecisionService)
+            .doesMeetAudienceConditions(config: config,
+                                        experiment: experiment,
+                                        userId: kUserId,
+                                        attributes: attributes).result!
         XCTAssert(isValid)
     }
     
     // TODO: transfer valid ObjC SDK tests
-
+    
 }
diff --git a/Tests/OptimizelyTests-Common/OptimizelyUserContextTests.swift b/Tests/OptimizelyTests-Common/OptimizelyUserContextTests.swift
new file mode 100644
index 000000000..21094697b
--- /dev/null
+++ b/Tests/OptimizelyTests-Common/OptimizelyUserContextTests.swift
@@ -0,0 +1,208 @@
+/****************************************************************************
+* Copyright 2021, Optimizely, Inc. and contributors                        *
+*                                                                          *
+* Licensed under the Apache License, Version 2.0 (the "License");          *
+* you may not use this file except in compliance with the License.         *
+* You may obtain a copy of the License at                                  *
+*                                                                          *
+*    http://www.apache.org/licenses/LICENSE-2.0                            *
+*                                                                          *
+* Unless required by applicable law or agreed to in writing, software      *
+* distributed under the License is distributed on an "AS IS" BASIS,        *
+* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. *
+* See the License for the specific language governing permissions and      *
+* limitations under the License.                                           *
+***************************************************************************/
+    
+
+import XCTest
+
+class OptimizelyUserContextTests: XCTestCase {
+    
+    let exp1Key = "exp_with_audience"
+    let var1AKey = "a"
+    let var1BKey = "b"
+    let exp1Id = "10390977673"
+    let var1AId = "10389729780"
+    let var1BId = "10416523121"
+
+    let exp2Key = "exp_no_audience"
+    let var2AKey = "variation_with_traffic"
+    let var2BKey = "variation_no_traffic"
+    let exp2Id = "10420810910"
+    let var2AId = "10418551353"
+    let var2BId = "10418510624"
+
+    let expUserId = "1234"
+    let expUserId2 = "3456"
+    let expOptimizely = OptimizelyClient(sdkKey: "any")
+
+    func testOptimizelyUserContext_userId() {
+        let user = OptimizelyUserContext(optimizely: expOptimizely, userId: expUserId)
+        
+        XCTAssert(user.optimizely == expOptimizely)
+        XCTAssert(user.userId == expUserId)
+        XCTAssert(user.attributes.count == 0)
+    }
+    
+    func testOptimizelyUserContext_nilAttributes() {
+        let user = OptimizelyUserContext(optimizely: expOptimizely, userId: expUserId, attributes: nil)
+        
+        XCTAssert(user.optimizely == expOptimizely)
+        XCTAssert(user.userId == expUserId)
+        XCTAssert(user.attributes.count == 0)
+    }
+
+    func testOptimizelyUserContext_attributes() {
+        let attributes: [String: Any] = [
+            "country": "us",
+            "age": 100,
+            "old": true
+        ]
+        let user = OptimizelyUserContext(optimizely: expOptimizely, userId: expUserId, attributes: attributes)
+        
+        XCTAssert(user.optimizely == expOptimizely)
+        XCTAssert(user.userId == expUserId)
+        XCTAssert(user.attributes["country"] as! String == "us")
+        XCTAssert(user.attributes["age"] as! Int == 100)
+        XCTAssert(user.attributes["old"] as! Bool == true)
+    }
+
+    func testOptimizelyUserContext_setAttribute() {
+        let user = OptimizelyUserContext(optimizely: expOptimizely, userId: expUserId, attributes: nil)
+        user.setAttribute(key: "state", value: "ca")
+        user.setAttribute(key: "num", value: 200)
+        user.setAttribute(key: "many", value: false)
+
+        XCTAssert(user.optimizely == expOptimizely)
+        XCTAssert(user.userId == expUserId)
+        XCTAssert(user.attributes["state"] as! String == "ca")
+        XCTAssert(user.attributes["num"] as! Int == 200)
+        XCTAssert(user.attributes["many"] as! Bool == false)
+    }
+
+    func testOptimizelyUserContext_setAttribute2() {
+        let attributes: [String: Any] = [
+            "country": "us",
+            "age": 100,
+            "old": true
+        ]
+        let user = OptimizelyUserContext(optimizely: expOptimizely, userId: expUserId, attributes: attributes)
+        user.setAttribute(key: "state", value: "ca")
+
+        XCTAssert(user.optimizely == expOptimizely)
+        XCTAssert(user.userId == expUserId)
+        XCTAssert(user.attributes["country"] as! String == "us")
+        XCTAssert(user.attributes["age"] as! Int == 100)
+        XCTAssert(user.attributes["old"] as! Bool == true)
+        XCTAssert(user.attributes["state"] as! String == "ca")
+    }
+    
+    func testOptimizelyUserContext_setAttribute3() {
+        let attributes: [String: Any] = ["country": "us"]
+        let user = OptimizelyUserContext(optimizely: expOptimizely, userId: expUserId, attributes: attributes)
+        XCTAssert(user.attributes["country"] as! String == "us")
+
+        user.setAttribute(key: "country", value: "fr")
+        XCTAssert(user.attributes["country"] as! String == "fr")
+    }
+    
+    func testOptimizelyUserContext_setAttribute_concurrent() {
+        let user = OptimizelyUserContext(optimizely: expOptimizely, userId: expUserId)
+        
+        user.setAttribute(key: "state", value: "ca")
+        user.setAttribute(key: "age", value: 18)
+
+        let expWrite = expectation(description: "write")
+        DispatchQueue.global().async {
+            for _ in 0..<10000 {
+                user.setAttribute(key: "state", value: "ca")
+                user.setAttribute(key: "age", value: 18)
+            }
+            expWrite.fulfill()
+        }
+        
+        let expRead = expectation(description: "read")
+        var attributes: [String: Any?]?
+        DispatchQueue.global().async {
+            for _ in 0..<10000 {
+                attributes = user.attributes
+                XCTAssert(attributes!["state"] as! String == "ca")
+                XCTAssert(attributes!["age"] as! Int == 18)
+            }
+            expRead.fulfill()
+        }
+
+        wait(for: [expWrite, expRead], timeout: 10)
+    }
+    
+    func testOptimizelyUserContext_callerAttributesChangeShouldNotBeReflected() {
+        var attributes: [String: Any] = ["country": "us"]
+        let user = OptimizelyUserContext(optimizely: expOptimizely, userId: expUserId, attributes: attributes)
+        attributes["country"] = "fr"
+        XCTAssert(user.attributes["country"] as! String == "us")
+    }
+    
+    func testOptimizelyUserContext_nilAttributeValue()  {
+        let attributes: [String: Any?] = [
+            "country": "us",
+            "age": nil,
+        ]
+        let user = OptimizelyUserContext(optimizely: expOptimizely, userId: expUserId, attributes: attributes)
+
+        XCTAssert(user.attributes["country"] as! String == "us")
+        XCTAssert(user.attributes["age"]! == nil)
+    }
+    
+    func testOptimizelyUserContext_nilAttributeValue2()  {
+        let attributes: [String: Any?] = [
+            "country": "us",
+            "age": nil,
+        ]
+        let user = OptimizelyUserContext(optimizely: expOptimizely, userId: expUserId, attributes: attributes)
+        user.setAttribute(key: "country", value: nil)
+        user.setAttribute(key: "age", value: 18)
+        user.setAttribute(key: "old", value: nil)
+
+        XCTAssert(user.attributes["country"]! == nil)
+        XCTAssert(user.attributes["age"] as! Int == 18)
+        XCTAssert(user.attributes["old"]! == nil)
+    }
+
+    func testOptimizelyUserContext_equal() {
+        let userId1 = "user1"
+        let userId2 = "user2"
+
+        let attributes1: [String: Any?] = [
+            "country": "us",
+            "age": nil,
+            "old": true
+        ]
+        
+        let attributes2: [String: Any?] = [
+            "country": "ca",
+            "age": nil,
+            "old": true
+        ]
+
+        let attributes3: [String: Any?] = [
+            "country": "us",
+            "age": nil,
+            "old": false
+        ]
+        
+        let attributes4: [String: Any?] = [
+            "country": "us",
+            "age": 18,
+            "old": true
+        ]
+
+        let user = OptimizelyUserContext(optimizely: expOptimizely, userId: userId1, attributes: attributes1)
+        XCTAssertEqual(user, OptimizelyUserContext(optimizely: expOptimizely, userId: userId1, attributes: attributes1))
+        XCTAssertNotEqual(user, OptimizelyUserContext(optimizely: expOptimizely, userId: userId2, attributes: attributes1))
+        XCTAssertNotEqual(user, OptimizelyUserContext(optimizely: expOptimizely, userId: userId1, attributes: attributes2))
+        XCTAssertNotEqual(user, OptimizelyUserContext(optimizely: expOptimizely, userId: userId1, attributes: attributes3))
+        XCTAssertNotEqual(user, OptimizelyUserContext(optimizely: expOptimizely, userId: userId1, attributes: attributes4))
+    }
+
+}
diff --git a/Tests/OptimizelyTests-Common/OptimizelyUserContextTests_Decide.swift b/Tests/OptimizelyTests-Common/OptimizelyUserContextTests_Decide.swift
new file mode 100644
index 000000000..84fd5ffa4
--- /dev/null
+++ b/Tests/OptimizelyTests-Common/OptimizelyUserContextTests_Decide.swift
@@ -0,0 +1,568 @@
+/****************************************************************************
+ * Copyright 2021, Optimizely, Inc. and contributors                        *
+ *                                                                          *
+ * Licensed under the Apache License, Version 2.0 (the "License");          *
+ * you may not use this file except in compliance with the License.         *
+ * You may obtain a copy of the License at                                  *
+ *                                                                          *
+ *    http://www.apache.org/licenses/LICENSE-2.0                            *
+ *                                                                          *
+ * Unless required by applicable law or agreed to in writing, software      *
+ * distributed under the License is distributed on an "AS IS" BASIS,        *
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. *
+ * See the License for the specific language governing permissions and      *
+ * limitations under the License.                                           *
+ ***************************************************************************/
+
+import XCTest
+
+class OptimizelyUserContextTests_Decide: XCTestCase {
+
+    let kUserId = "tester"
+    
+    var optimizely: OptimizelyClient!
+    var eventDispatcher = MockEventDispatcher()
+    var decisionService: DefaultDecisionService!
+    var ups: OPTUserProfileService!
+
+    override func setUp() {
+        super.setUp()
+        
+        let datafile = OTUtils.loadJSONDatafile("decide_datafile")!
+        optimizely = OptimizelyClient(sdkKey: OTUtils.randomSdkKey,
+                                      eventDispatcher: eventDispatcher,
+                                      userProfileService: OTUtils.createClearUserProfileService())
+        decisionService = (optimizely.decisionService as! DefaultDecisionService)
+        ups = decisionService.userProfileService
+        try! optimizely.start(datafile: datafile)
+    }
+   
+    func testCreateUserContext() {
+        let userId = "tester"
+        let attributes: [String: Any] = [
+            "country": "us",
+            "age": 100,
+            "old": true
+        ]
+        
+        let user = optimizely.createUserContext(userId: "tester", attributes: attributes)
+        
+        XCTAssert(user.optimizely == optimizely)
+        XCTAssert(user.userId == userId)
+        XCTAssert(user.attributes["country"] as! String == "us")
+        XCTAssert(user.attributes["age"] as! Int == 100)
+        XCTAssert(user.attributes["old"] as! Bool == true)
+    }
+    
+    func testCreateUserContext_multiple() {
+        let attributes: [String: Any] = [
+            "country": "us",
+            "age": 100,
+            "old": true
+        ]
+        let user1 = optimizely.createUserContext(userId: "tester1", attributes: attributes)
+        let user2 = optimizely.createUserContext(userId: "tester2", attributes: [:])
+        
+        XCTAssert(user1.userId == "tester1")
+        XCTAssert(user2.userId == "tester2")
+    }
+    
+    func testDefaultDecideOptions() {
+        let expOptions: [OptimizelyDecideOption] = [.ignoreUserProfileService,
+                                                    .disableDecisionEvent,
+                                                    .enabledFlagsOnly,
+                                                    .includeReasons,
+                                                    .excludeVariables]
+        
+        optimizely = OptimizelyClient(sdkKey: OTUtils.randomSdkKey)
+        XCTAssert(optimizely.defaultDecideOptions.count == 0)
+
+        optimizely = OptimizelyClient(sdkKey: OTUtils.randomSdkKey,
+                                      defaultDecideOptions: expOptions)
+        XCTAssert(optimizely.defaultDecideOptions == expOptions)
+    }
+    
+}
+
+// MARK: - decide
+
+extension OptimizelyUserContextTests_Decide {
+
+    func testDecide() {
+        let featureKey = "feature_2"
+        let variablesExpected = try! optimizely.getAllFeatureVariables(featureKey: featureKey, userId: kUserId)
+
+        let user = optimizely.createUserContext(userId: kUserId)
+        let decision = user.decide(key: featureKey)
+        
+        XCTAssertEqual(decision.variationKey, "variation_with_traffic")
+        XCTAssertTrue(decision.enabled)
+        XCTAssertTrue(NSDictionary(dictionary: decision.variables.toMap()).isEqual(to: variablesExpected.toMap()))
+        XCTAssertEqual(decision.ruleKey, "exp_no_audience")
+        XCTAssertEqual(decision.flagKey, featureKey)
+        XCTAssertEqual(decision.userContext, user)
+        XCTAssert(decision.reasons.isEmpty)
+    }
+    
+}
+
+// MARK: - impression events
+
+extension OptimizelyUserContextTests_Decide {
+    
+    // NOTE: we here validate impression events only.
+    //       all decision-notification tests are in "OptimizelyTests-Common/DecisionListenerTests"
+    
+    func testDecide_sendImpression() {
+        let featureKey = "feature_2"
+
+        let user = optimizely.createUserContext(userId: kUserId)
+        let decision = user.decide(key: featureKey)
+        
+        optimizely.eventLock.sync{}
+
+        XCTAssertEqual(decision.variationKey, "variation_with_traffic")
+        XCTAssertTrue(decision.enabled)
+        XCTAssertNotNil(eventDispatcher.eventSent)
+        
+        let eventSent = eventDispatcher.eventSent!
+        let event = try! JSONDecoder().decode(BatchEvent.self, from: eventSent.body)
+        let eventDecision: Decision = event.visitors[0].snapshots[0].decisions![0]
+        let metadata = eventDecision.metaData
+
+        let desc = eventDispatcher.eventSent!.description
+        XCTAssert(desc.contains("campaign_activated"))
+        
+        XCTAssertEqual(eventDecision.experimentID, "10420810910")
+        XCTAssertEqual(eventDecision.variationID, "10418551353")
+
+        XCTAssertEqual(metadata.flagKey, "feature_2")
+        XCTAssertEqual(metadata.ruleKey, "exp_no_audience")
+        XCTAssertEqual(metadata.ruleType, "feature-test")
+        XCTAssertEqual(metadata.variationKey, "variation_with_traffic")
+        XCTAssertEqual(metadata.enabled, true)
+    }
+    
+    func testDecide_sendImpressionForNullVariation() {
+        let featureKey = "feature_3"
+
+        let user = optimizely.createUserContext(userId: kUserId)
+        _ = user.decide(key: featureKey)
+        
+        optimizely.eventLock.sync{}
+
+        XCTAssertNotNil(eventDispatcher.eventSent)
+        
+        let eventSent = eventDispatcher.eventSent!
+        let event = try! JSONDecoder().decode(BatchEvent.self, from: eventSent.body)
+        let eventDecision: Decision = event.visitors[0].snapshots[0].decisions![0]
+        let metadata = eventDecision.metaData
+        
+        let desc = eventDispatcher.eventSent!.description
+        XCTAssert(desc.contains("campaign_activated"))
+        
+        XCTAssertEqual(eventDecision.variationID, "")
+        XCTAssertEqual(eventDecision.experimentID, "")
+
+        XCTAssertEqual(metadata.flagKey, "feature_3")
+        XCTAssertEqual(metadata.ruleKey, "")
+        XCTAssertEqual(metadata.ruleType, "rollout")
+        XCTAssertEqual(metadata.variationKey, "")
+        XCTAssertEqual(metadata.enabled, false)
+    }
+
+    func testDecide_doNotSendImpression() {
+        let featureKey = "invalid"   // invalid flag
+
+        let user = optimizely.createUserContext(userId: kUserId)
+        let decision = user.decide(key: featureKey)
+        
+        optimizely.eventLock.sync{}
+
+        XCTAssertNil(decision.variationKey)
+        XCTAssertFalse(decision.enabled)
+        XCTAssertNil(eventDispatcher.eventSent)
+    }
+    
+}
+
+// MARK: - decideForKeys API
+
+extension OptimizelyUserContextTests_Decide {
+
+    func testDecideForKeys_oneFeature() {
+        let featureKey = "feature_2"
+        let featureKeys = [featureKey]
+        let variablesExpected = try! optimizely.getAllFeatureVariables(featureKey: featureKey, userId: kUserId)
+        let user = optimizely.createUserContext(userId: kUserId)
+        let decisions = user.decide(keys: featureKeys)
+        
+        XCTAssert(decisions.count == 1)
+        let decision = decisions[featureKey]!
+        
+        let expDecision = OptimizelyDecision(variationKey: "variation_with_traffic",
+                                             enabled: true,
+                                             variables: variablesExpected,
+                                             ruleKey: "exp_no_audience",
+                                             flagKey: featureKey,
+                                             userContext: user,
+                                             reasons: [])
+        XCTAssertEqual(decision, expDecision)
+    }
+    
+    func testDecideForKeys_twoFeatures() {
+        let featureKey1 = "feature_1"
+        let featureKey2 = "feature_2"
+        
+        let featureKeys = [featureKey1, featureKey2]
+        let variablesExpected1 = try! optimizely.getAllFeatureVariables(featureKey: featureKey1, userId: kUserId)
+        let variablesExpected2 = try! optimizely.getAllFeatureVariables(featureKey: featureKey2, userId: kUserId)
+        
+        let user = optimizely.createUserContext(userId: kUserId, attributes: ["gender": "f"])
+        let decisions = user.decide(keys: featureKeys)
+        
+        XCTAssert(decisions.count == 2)
+        
+        XCTAssert(decisions[featureKey1]! == OptimizelyDecision(variationKey: "a",
+                                                                enabled: true,
+                                                                variables: variablesExpected1,
+                                                                ruleKey: "exp_with_audience",
+                                                                flagKey: featureKey1,
+                                                                userContext: user,
+                                                                reasons: []))
+        XCTAssert(decisions[featureKey2]! == OptimizelyDecision(variationKey: "variation_with_traffic",
+                                                                enabled: true,
+                                                                variables: variablesExpected2,
+                                                                ruleKey: "exp_no_audience",
+                                                                flagKey: featureKey2,
+                                                                userContext: user,
+                                                                reasons: []))
+    }
+    
+    func testDecideForKeys_emptyKeys() {
+        let featureKeys = [String]()
+        
+        let user = optimizely.createUserContext(userId: kUserId)
+        let decisions = user.decide(keys: featureKeys)
+        
+        XCTAssert(decisions.count == 0)
+    }
+        
+}
+
+// MARK: - decideAll API
+
+extension OptimizelyUserContextTests_Decide {
+    
+    func testDecideAll() {
+        let featureKey1 = "feature_1"
+        let featureKey2 = "feature_2"
+        let featureKey3 = "feature_3"
+        
+        let variablesExpected1 = try! optimizely.getAllFeatureVariables(featureKey: featureKey1, userId: kUserId)
+        let variablesExpected2 = try! optimizely.getAllFeatureVariables(featureKey: featureKey2, userId: kUserId)
+        let variablesExpected3 = OptimizelyJSON.createEmpty()
+        
+        let user = optimizely.createUserContext(userId: kUserId, attributes: ["gender": "f"])
+        let decisions = user.decideAll()
+        
+        XCTAssert(decisions.count == 3)
+        
+        XCTAssert(decisions[featureKey1]! == OptimizelyDecision(variationKey: "a",
+                                                                enabled: true,
+                                                                variables: variablesExpected1,
+                                                                ruleKey: "exp_with_audience",
+                                                                flagKey: featureKey1,
+                                                                userContext: user,
+                                                                reasons: []))
+        XCTAssert(decisions[featureKey2]! == OptimizelyDecision(variationKey: "variation_with_traffic",
+                                                                enabled: true,
+                                                                variables: variablesExpected2,
+                                                                ruleKey: "exp_no_audience",
+                                                                flagKey: featureKey2,
+                                                                userContext: user,
+                                                                reasons: []))
+        XCTAssert(decisions[featureKey3]! == OptimizelyDecision(variationKey: nil,
+                                                                enabled: false,
+                                                                variables: variablesExpected3,
+                                                                ruleKey: nil,
+                                                                flagKey: featureKey3,
+                                                                userContext: user,
+                                                                reasons: []))
+    }
+    
+    func testDecideAll_enabledOnly() {
+        let featureKey1 = "feature_1"
+        let variablesExpected1 = try! optimizely.getAllFeatureVariables(featureKey: featureKey1, userId: kUserId)
+        
+        let user = optimizely.createUserContext(userId: kUserId, attributes: ["gender": "f"])
+        let decisions = user.decideAll(options: [.enabledFlagsOnly])
+        
+        XCTAssert(decisions.count == 2)
+        
+        XCTAssert(decisions[featureKey1]! == OptimizelyDecision(variationKey: "a",
+                                                                enabled: true,
+                                                                variables: variablesExpected1,
+                                                                ruleKey: "exp_with_audience",
+                                                                flagKey: featureKey1,
+                                                                userContext: user,
+                                                                reasons: []))
+    }
+
+}
+
+// MARK: - options
+
+extension OptimizelyUserContextTests_Decide {
+    
+    func testDecide_sendImpression_disbleTracking() {
+        let featureKey = "feature_2"
+
+        let user = optimizely.createUserContext(userId: kUserId)
+        let decision = user.decide(key: featureKey, options: [.disableDecisionEvent])
+        
+        optimizely.eventLock.sync{}
+
+        XCTAssertTrue(decision.enabled)
+        XCTAssertNil(eventDispatcher.eventSent)
+    }
+    
+    func testDecideOptions_useUPSbyDefault() {
+        let featureKey = "feature_2"        // embedding experiment: "exp_no_audience"
+        let experimentId = "10420810910"    // "exp_no_audience"
+        let variationId = "10418551353"
+
+        let user = optimizely.createUserContext(userId: kUserId)
+        
+        XCTAssertNil(OTUtils.getVariationFromUPS(ups: ups, userId: kUserId, experimentId: experimentId))
+
+        // this will set UPS
+        _ = user.decide(key: featureKey)
+        
+        XCTAssert(OTUtils.getVariationFromUPS(ups: ups, userId: kUserId, experimentId: experimentId) == variationId)
+    }
+    
+    func testDecideOptions_bypassUPS_doNotUpdateUPS() {
+        let featureKey = "feature_2"        // embedding experiment: "exp_no_audience"
+        let experimentId = "10420810910"    // "exp_no_audience"
+
+        let user = optimizely.createUserContext(userId: kUserId)
+
+        XCTAssertNil(getProfileVariation(userId: kUserId, experimentId: experimentId))
+
+        // this will not set UPS because of bypassUPS option
+        _ = user.decide(key: featureKey, options: [.ignoreUserProfileService])
+        
+        XCTAssertNil(OTUtils.getVariationFromUPS(ups: ups, userId: kUserId, experimentId: experimentId))
+    }
+
+    func testDecideOptions_bypassUPS_doNotReadUPS() {
+        let featureKey = "feature_2"        // embedding experiment: "exp_no_audience"
+        let experimentId = "10420810910"    // "exp_no_audience"
+        let variationKey1 = "variation_with_traffic"
+        let variationKey2 = "variation_no_traffic"
+        let variationId2 = "10418510624"
+
+        let user = optimizely.createUserContext(userId: kUserId)
+
+        setProfileVariation(userId: kUserId, experimentId: experimentId, variationId: variationId2)
+        XCTAssert(getProfileVariation(userId: kUserId, experimentId: experimentId) == variationId2)
+
+        let decision1 = user.decide(key: featureKey)
+        let decision2 = user.decide(key: featureKey, options: [.ignoreUserProfileService])
+
+        XCTAssert(decision1.variationKey == variationKey2)
+        XCTAssert(decision2.variationKey == variationKey1)
+    }
+    
+    func testDecide_excludeVariables() {
+        let featureKey = "feature_1"
+        let variablesExpected = try! optimizely.getAllFeatureVariables(featureKey: featureKey, userId: kUserId)
+
+        let user = optimizely.createUserContext(userId: kUserId)
+        
+        var decision = user.decide(key: featureKey)
+        XCTAssertTrue(NSDictionary(dictionary: decision.variables.toMap()).isEqual(to: variablesExpected.toMap()))
+        
+        decision = user.decide(key: featureKey, options: [.excludeVariables])
+        XCTAssertTrue(decision.variables.isEmpty)
+    }
+    
+    func testDecide_defaultDecideOption() {
+        let featureKey = "feature_1"
+        let variablesExpected = try! optimizely.getAllFeatureVariables(featureKey: featureKey, userId: kUserId)
+
+        var user = optimizely.createUserContext(userId: kUserId)
+        var decision = user.decide(key: featureKey)
+        XCTAssertTrue(NSDictionary(dictionary: decision.variables.toMap()).isEqual(to: variablesExpected.toMap()))
+        
+        // new optimizley instance with defaultDecideOptions and a new user-context
+        
+        let datafile = OTUtils.loadJSONDatafile("decide_datafile")!
+        optimizely = OptimizelyClient(sdkKey: OTUtils.randomSdkKey,
+                                      defaultDecideOptions: [.excludeVariables])
+        try! optimizely.start(datafile: datafile)
+        user = optimizely.createUserContext(userId: kUserId)
+        decision = user.decide(key: featureKey)
+        XCTAssertTrue(decision.variables.isEmpty)
+    }
+
+}
+    
+// MARK: - debugging reasons
+  
+extension OptimizelyUserContextTests_Decide {
+
+}
+
+// MARK: - errors
+  
+extension OptimizelyUserContextTests_Decide {
+    
+    func testDecide_sdkNotReady() {
+        let featureKey = "feature_1"
+        
+        self.optimizely = OptimizelyClient(sdkKey: "12345",
+                                           userProfileService: OTUtils.createClearUserProfileService())
+
+        let user = optimizely.createUserContext(userId: kUserId)
+        let decision = user.decide(key: featureKey)
+        
+        XCTAssertNil(decision.variationKey)
+        XCTAssertFalse(decision.enabled)
+        XCTAssertTrue(decision.variables.isEmpty)
+        XCTAssertNil(decision.ruleKey)
+        XCTAssertEqual(decision.flagKey, featureKey)
+        XCTAssertEqual(decision.userContext, user)
+        
+        XCTAssert(decision.reasons.count == 1)
+        XCTAssert(decision.reasons.first == OptimizelyError.sdkNotReady.reason)
+    }
+    
+    func testDecide_sdkNotReady_optimizelyReleased() {
+        let featureKey = "feature_1"
+
+        var optimizelyClient: OptimizelyClient! = OptimizelyClient(sdkKey: OTUtils.randomSdkKey)
+        let datafile = OTUtils.loadJSONDatafile("decide_datafile")!
+        try! optimizelyClient.start(datafile: datafile)
+
+        let user = optimizelyClient.createUserContext(userId: kUserId)
+        
+        // optimizelyClient released and the weak ref in userContext will become nil
+        optimizelyClient = nil
+        let decision = user.decide(key: featureKey)
+        
+        XCTAssertNil(decision.variationKey)
+        XCTAssert(decision.reasons.count == 1)
+        XCTAssert(decision.reasons.first == OptimizelyError.sdkNotReady.reason)
+    }
+
+    func testDecide_invalidFeatureKey() {
+        let featureKey = "invalid_key"
+
+        let user = optimizely.createUserContext(userId: kUserId)
+
+        let decision = user.decide(key: featureKey)
+
+        XCTAssertNil(decision.variationKey)
+        XCTAssertFalse(decision.enabled)
+        XCTAssertTrue(decision.variables.isEmpty)
+        XCTAssertNil(decision.ruleKey)
+        XCTAssert(decision.reasons.count == 1)
+        XCTAssert(decision.reasons.first == OptimizelyError.featureKeyInvalid(featureKey).reason)
+    }
+        
+    // decideForKeys
+    
+    func testDecideForKeys_sdkNotReady() {
+        let featureKeys = ["feature_1"]
+        
+        self.optimizely = OptimizelyClient(sdkKey: "12345",
+                                           userProfileService: OTUtils.createClearUserProfileService())
+        
+        let user = optimizely.createUserContext(userId: kUserId)
+        let decisions = user.decide(keys: featureKeys)
+        
+        XCTAssert(decisions.count == 0)
+    }
+    
+    func testDecideForKeys_sdkNotReady_optimizelyReleased() {
+        let featureKeys = ["feature_1"]
+
+        var optimizelyClient: OptimizelyClient! = OptimizelyClient(sdkKey: OTUtils.randomSdkKey)
+        let datafile = OTUtils.loadJSONDatafile("decide_datafile")!
+        try! optimizelyClient.start(datafile: datafile)
+
+        let user = optimizelyClient.createUserContext(userId: kUserId)
+        
+        // optimizelyClient released and the weak ref in userContext will become nil
+        optimizelyClient = nil
+        let decisions = user.decide(keys: featureKeys)
+        
+        XCTAssert(decisions.count == 0)
+    }
+    
+    func testDecideForKeys_errorDecisionIncluded() {
+        let featureKey1 = "feature_2"
+        let featureKey2 = "invalid_key"
+
+        let featureKeys = [featureKey1, featureKey2]
+        let variablesExpected1 = try! optimizely.getAllFeatureVariables(featureKey: featureKey1, userId: kUserId)
+        
+        let user = optimizely.createUserContext(userId: kUserId)
+        let decisions = user.decide(keys: featureKeys)
+        
+        XCTAssert(decisions.count == 2)
+        
+        XCTAssert(decisions[featureKey1]! == OptimizelyDecision(variationKey: "variation_with_traffic",
+                                                                enabled: true,
+                                                                variables: variablesExpected1,
+                                                                ruleKey: "exp_no_audience",
+                                                                flagKey: featureKey1,
+                                                                userContext: user,
+                                                                reasons: []))
+        XCTAssert(decisions[featureKey2]! == OptimizelyDecision.errorDecision(key: featureKey2,
+                                                                              user: user,
+                                                                              error: .featureKeyInvalid(featureKey2)))
+    }
+
+}
+
+// MARK: - helpers
+
+extension OptimizelyUserContextTests_Decide {
+    func getProfileVariation(userId: String, experimentId: String) -> String? {
+        if let profile = decisionService.userProfileService.lookup(userId: userId),
+            let bucketMap = profile[UserProfileKeys.kBucketMap] as? OPTUserProfileService.UPBucketMap,
+            let experimentMap = bucketMap[experimentId],
+            let variationId = experimentMap[UserProfileKeys.kVariationId] {
+            return variationId
+        } else {
+            return nil
+        }
+    }
+    
+    func setProfileVariation(userId: String, experimentId: String, variationId: String){
+        var profile = decisionService.userProfileService.lookup(userId: userId) ?? OPTUserProfileService.UPProfile()
+        
+        var bucketMap = profile[UserProfileKeys.kBucketMap] as? OPTUserProfileService.UPBucketMap ?? OPTUserProfileService.UPBucketMap()
+        bucketMap[experimentId] = [UserProfileKeys.kVariationId: variationId]
+        
+        profile[UserProfileKeys.kBucketMap] = bucketMap
+        profile[UserProfileKeys.kUserId] = userId
+        
+        decisionService.userProfileService.save(userProfile: profile)
+    }
+}
+    
+class MockEventDispatcher: OPTEventDispatcher {
+    var eventSent: EventForDispatch?
+    
+    func dispatchEvent(event: EventForDispatch, completionHandler: DispatchCompletionHandler?) {
+        eventSent = event
+    }
+    
+    func flushEvents() {
+        
+    }
+}
diff --git a/Tests/OptimizelyTests-Common/OptimizelyUserContextTests_Decide_Legacy.swift b/Tests/OptimizelyTests-Common/OptimizelyUserContextTests_Decide_Legacy.swift
new file mode 100644
index 000000000..00120c728
--- /dev/null
+++ b/Tests/OptimizelyTests-Common/OptimizelyUserContextTests_Decide_Legacy.swift
@@ -0,0 +1,70 @@
+/****************************************************************************
+ * Copyright 2021
+ *                                                                          *
+ * Licensed under the Apache License, Version 2.0 (the "License");          *
+ * you may not use this file except in compliance with the License.         *
+ * You may obtain a copy of the License at                                  *
+ *                                                                          *
+ *    http://www.apache.org/licenses/LICENSE-2.0                            *
+ *                                                                          *
+ * Unless required by applicable law or agreed to in writing, software      *
+ * distributed under the License is distributed on an "AS IS" BASIS,        *
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. *
+ * See the License for the specific language governing permissions and      *
+ * limitations under the License.                                           *
+ ***************************************************************************/
+
+import XCTest
+
+class OptimizelyUserContextTests_Decide_Legacy: XCTestCase {
+    
+    let kUserId = "tester"
+    let kAttributes = ["country": "US"]
+    let kEventKey = "any-event"
+    let kEventTags = ["name": "carrot"]
+    
+    class MockOptimizelyClient: OptimizelyClient {
+        var trackEventKey: String?
+        var trackUserId: String?
+        var trackAttributes: [String: String]?
+        var trackEventTags: [String: String]?
+        
+        override func track(eventKey: String,
+                            userId: String,
+                            attributes: OptimizelyAttributes? = nil,
+                            eventTags: OptimizelyEventTags? = nil) throws {
+            trackEventKey = eventKey
+            trackUserId = userId
+            trackAttributes = attributes as? [String: String]
+            trackEventTags = eventTags as? [String: String]
+        }
+    }
+    
+    var optimizely: MockOptimizelyClient!
+
+    override func setUp() {
+        super.setUp()
+        
+        let datafile = OTUtils.loadJSONDatafile("decide_datafile")!
+        optimizely = MockOptimizelyClient(sdkKey: OTUtils.randomSdkKey,
+                                          userProfileService: OTUtils.createClearUserProfileService())
+        try! optimizely.start(datafile: datafile)
+    }
+    
+}
+
+// MARK: - legacy APIs with UserContext
+
+extension OptimizelyUserContextTests_Decide_Legacy {
+    
+    func testTrackEventWithUserContext() {
+        let user = optimizely.createUserContext(userId: kUserId, attributes: kAttributes)
+        try! user.trackEvent(eventKey: kEventKey, eventTags: kEventTags)
+        
+        XCTAssertEqual(optimizely.trackEventKey, kEventKey)
+        XCTAssertEqual(optimizely.trackUserId, kUserId)
+        XCTAssertEqual(optimizely.trackAttributes, kAttributes)
+        XCTAssertEqual(optimizely.trackEventTags, kEventTags)
+    }
+        
+}
diff --git a/Tests/OptimizelyTests-Common/OptimizelyUserContextTests_Decide_Reasons.swift b/Tests/OptimizelyTests-Common/OptimizelyUserContextTests_Decide_Reasons.swift
new file mode 100644
index 000000000..cb5aa37e4
--- /dev/null
+++ b/Tests/OptimizelyTests-Common/OptimizelyUserContextTests_Decide_Reasons.swift
@@ -0,0 +1,509 @@
+/****************************************************************************
+ * Copyright 2021, Optimizely, Inc. and contributors                        *
+ *                                                                          *
+ * Licensed under the Apache License, Version 2.0 (the "License");          *
+ * you may not use this file except in compliance with the License.         *
+ * You may obtain a copy of the License at                                  *
+ *                                                                          *
+ *    http://www.apache.org/licenses/LICENSE-2.0                            *
+ *                                                                          *
+ * Unless required by applicable law or agreed to in writing, software      *
+ * distributed under the License is distributed on an "AS IS" BASIS,        *
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. *
+ * See the License for the specific language governing permissions and      *
+ * limitations under the License.                                           *
+ ***************************************************************************/
+
+import XCTest
+
+class OptimizelyUserContextTests_Decide_Reasons: XCTestCase {
+    
+    let kUserId = "tester"
+    
+    var optimizely: OptimizelyClient!
+    var decisionService: DefaultDecisionService!
+    var ups: OPTUserProfileService!
+    var user: OptimizelyUserContext!
+
+    override func setUp() {
+        super.setUp()
+        
+        optimizely = OptimizelyClient(sdkKey: OTUtils.randomSdkKey,
+                                      userProfileService: OTUtils.createClearUserProfileService())
+        user = optimizely.createUserContext(userId: kUserId)
+        decisionService = optimizely.decisionService as? DefaultDecisionService
+        ups = decisionService.userProfileService
+        try! optimizely.start(datafile: OTUtils.loadJSONDatafile("decide_datafile")!)
+    }
+    
+}
+
+// MARK: - error reasons (always included)
+
+extension OptimizelyUserContextTests_Decide_Reasons {
+
+    func testDecideReasons_sdkNotReady() {
+        optimizely = OptimizelyClient(sdkKey: OTUtils.randomSdkKey,
+                                      userProfileService: OTUtils.createClearUserProfileService())
+        try? optimizely.start(datafile: OTUtils.loadJSONDatafile("unsupported_datafile")!)
+        user = optimizely.createUserContext(userId: kUserId)
+
+        let decision = user.decide(key: "any-key")
+        XCTAssert(decision.hasFailed)
+        XCTAssertEqual(decision.reasons, [OptimizelyError.sdkNotReady.reason])
+    }
+    
+    func testDecideReasons_featureKeyInvalid() {
+        let key = "invalid-key"
+        let decision = user.decide(key: key)
+        XCTAssert(decision.hasFailed)
+        XCTAssertEqual(decision.reasons, [OptimizelyError.featureKeyInvalid(key).reason])
+    }
+        
+    func testDecideReasons_variableValueInvalid() {
+        let featureKey = "feature_1"
+        let rolloutId = "3319450668"
+        let integerVariableId = "2687470095"
+        let integerVariableKey = "i_42"
+
+        // inject invalid variable value
+        var rollout = optimizely.config!.getRollout(id: rolloutId)!
+        var rolloutVariation = rollout.experiments[0].variations[0]
+        rolloutVariation.variables = [Variable(id: integerVariableId, value: "invalid")]
+        rollout.experiments[0].variations[0] = rolloutVariation
+        optimizely.config!.rolloutIdMap = [rolloutId: rollout]
+        
+        user.setAttribute(key: "country", value: "US")
+        let decision = user.decide(key: featureKey)
+        XCTAssert(decision.reasons.contains(OptimizelyError.variableValueInvalid(integerVariableKey).reason))
+    }
+    
+}
+
+// MARK: - error messages (only with "includeReasons")
+
+extension OptimizelyUserContextTests_Decide_Reasons {
+
+    func testDecideReasons_conditionNoMatchingAudience() {
+        let featureKey = "feature_1"
+        let audienceId = "invalid_id"
+        setAudienceForFeatureTest(featureKey: featureKey, audienceId: audienceId)
+
+        var decision = user.decide(key: featureKey)
+        XCTAssert(decision.reasons.isEmpty)
+        decision = user.decide(key: featureKey, options: [.includeReasons])
+        XCTAssert(decision.reasons.contains(OptimizelyError.conditionNoMatchingAudience(audienceId).reason))
+    }
+    
+    func testDecideReasons_conditionInvalidFormat() {
+        let featureKey = "feature_1"
+        let audienceId = "invalid_format"
+        setAudienceForFeatureTest(featureKey: featureKey, audienceId: audienceId)
+
+        var decision = user.decide(key: featureKey)
+        XCTAssert(decision.reasons.isEmpty)
+        decision = user.decide(key: featureKey, options: [.includeReasons])
+        XCTAssert(decision.reasons.contains(OptimizelyError.conditionInvalidFormat("Empty condition array").reason))
+    }
+    
+    func testDecideReasons_evaluateAttributeInvalidCondition() {
+        let featureKey = "feature_1"
+        let audienceId = "invalid_condition"
+        setAudienceForFeatureTest(featureKey: featureKey, audienceId: audienceId)
+
+        let condition = "{\"match\":\"gt\",\"value\":\"US\",\"name\":\"age\",\"type\":\"custom_attribute\"}"
+        user.setAttribute(key: "age", value: 25)
+
+        var decision = user.decide(key: featureKey)
+        XCTAssert(decision.reasons.isEmpty)
+        decision = user.decide(key: featureKey, options: [.includeReasons])
+        XCTAssert(decision.reasons.contains(OptimizelyError.evaluateAttributeInvalidCondition(condition).reason))
+    }
+    
+    func testDecideReasons_evaluateAttributeInvalidType() {
+        let featureKey = "feature_1"
+        let audienceId = "13389130056"
+        setAudienceForFeatureTest(featureKey: featureKey, audienceId: audienceId)
+
+        let condition = "{\"match\":\"exact\",\"value\":\"US\",\"name\":\"country\",\"type\":\"custom_attribute\"}"
+        let attributeKey = "country"
+        let attributeValue = 25
+        user.setAttribute(key: attributeKey, value: attributeValue)
+        
+        var decision = user.decide(key: featureKey)
+        XCTAssert(decision.reasons.isEmpty)
+        decision = user.decide(key: featureKey, options: [.includeReasons])
+        XCTAssert(decision.reasons.contains(OptimizelyError.evaluateAttributeInvalidType(condition, attributeValue, attributeKey).reason))
+    }
+    
+    func testDecideReasons_evaluateAttributeValueOutOfRange() {
+        let featureKey = "feature_1"
+        let audienceId = "age_18"
+        setAudienceForFeatureTest(featureKey: featureKey, audienceId: audienceId)
+
+        let condition = "{\"match\":\"gt\",\"value\":18,\"name\":\"age\",\"type\":\"custom_attribute\"}"
+        user.setAttribute(key: "age", value: pow(2,54) as Double)   // TOO-BIG value
+        
+        var decision = user.decide(key: featureKey)
+        XCTAssert(decision.reasons.isEmpty)
+        decision = user.decide(key: featureKey, options: [.includeReasons])
+        XCTAssert(decision.reasons.contains(OptimizelyError.evaluateAttributeValueOutOfRange(condition, "age").reason))
+    }
+    
+    func testDecideReasons_userAttributeInvalidType() {
+        let featureKey = "feature_1"
+        let audienceId = "invalid_type"
+        setAudienceForFeatureTest(featureKey: featureKey, audienceId: audienceId)
+                
+        let condition = "{\"match\":\"gt\",\"value\":18,\"name\":\"age\",\"type\":\"invalid\"}"
+        user.setAttribute(key: "age", value: 25)
+        
+        var decision = user.decide(key: featureKey)
+        XCTAssert(decision.reasons.isEmpty)
+        decision = user.decide(key: featureKey, options: [.includeReasons])
+        XCTAssert(decision.reasons.contains(OptimizelyError.userAttributeInvalidType(condition).reason))
+    }
+    
+    func testDecideReasons_userAttributeInvalidMatch() {
+        let featureKey = "feature_1"
+        let audienceId = "invalid_match"
+        setAudienceForFeatureTest(featureKey: featureKey, audienceId: audienceId)
+                
+        let condition = "{\"match\":\"invalid\",\"value\":18,\"name\":\"age\",\"type\":\"custom_attribute\"}"
+        user.setAttribute(key: "age", value: 25)
+        
+        var decision = user.decide(key: featureKey)
+        XCTAssert(decision.reasons.isEmpty)
+        decision = user.decide(key: featureKey, options: [.includeReasons])
+        XCTAssert(decision.reasons.contains(OptimizelyError.userAttributeInvalidMatch(condition).reason))
+    }
+    
+    func testDecideReasons_userAttributeNilValue() {
+        let featureKey = "feature_1"
+        let audienceId = "nil_value"
+        setAudienceForFeatureTest(featureKey: featureKey, audienceId: audienceId)
+
+        let condition = "{\"name\":\"age\",\"type\":\"custom_attribute\",\"match\":\"gt\"}"
+        user.setAttribute(key: "age", value: 25)
+        
+        var decision = user.decide(key: featureKey)
+        XCTAssert(decision.reasons.isEmpty)
+        decision = user.decide(key: featureKey, options: [.includeReasons])
+        XCTAssert(decision.reasons.contains(OptimizelyError.userAttributeNilValue(condition).reason))
+    }
+    
+    func testDecideReasons_userAttributeInvalidName() {
+        let featureKey = "feature_1"
+        let audienceId = "invalid_name"
+        setAudienceForFeatureTest(featureKey: featureKey, audienceId: audienceId)
+                
+        let condition = "{\"type\":\"custom_attribute\",\"match\":\"gt\",\"value\":18}"
+        user.setAttribute(key: "age", value: 25)
+        
+        var decision = user.decide(key: featureKey)
+        XCTAssert(decision.reasons.isEmpty)
+        decision = user.decide(key: featureKey, options: [.includeReasons])
+        XCTAssert(decision.reasons.contains(OptimizelyError.userAttributeInvalidName(condition).reason))
+    }
+    
+    func testDecideReasons_missingAttributeValue() {
+        let featureKey = "feature_1"
+        let audienceId = "age_18"
+        setAudienceForFeatureTest(featureKey: featureKey, audienceId: audienceId)
+                
+        let condition = "{\"match\":\"gt\",\"value\":18,\"name\":\"age\",\"type\":\"custom_attribute\"}"
+        
+        var decision = user.decide(key: featureKey)
+        XCTAssert(decision.reasons.isEmpty)
+        decision = user.decide(key: featureKey, options: [.includeReasons])
+        XCTAssert(decision.reasons.contains(OptimizelyError.missingAttributeValue(condition, "age").reason))
+    }
+     
+}
+
+// MARK: - log messages (only with "includeReasons")
+
+extension OptimizelyUserContextTests_Decide_Reasons {
+
+    func testDecideReasons_experimentNotRunning() {
+        let featureKey = "feature_1"
+        let experimentKey = "exp_with_audience"
+        setStatusForFeatureTest(featureKey: featureKey, status: .paused)
+        
+        var decision = user.decide(key: featureKey)
+        XCTAssert(decision.reasons.isEmpty)
+        decision = user.decide(key: featureKey, options: [.includeReasons])
+        XCTAssert(decision.reasons.contains(LogMessage.experimentNotRunning(experimentKey).reason))
+    }
+    
+    func testDecideReasons_gotVariationFromUserProfile() {
+        let featureKey = "feature_1"        // embedding experiment: "exp_with_audience"
+        let experimentId = "10390977673"    // "exp_with_audience"
+        let experimentKey = "exp_with_audience"
+        let variationKey2 = "b"
+        let variationId2 = "10416523121"
+
+        OTUtils.setVariationToUPS(ups: ups, userId: kUserId, experimentId: experimentId, variationId: variationId2)
+        let decision = user.decide(key: featureKey, options: [.includeReasons])
+        
+        XCTAssertEqual(decision.variationKey, variationKey2)
+        XCTAssertEqual(decision.reasons,
+                       [LogMessage.gotVariationFromUserProfile(variationKey2, experimentKey, kUserId).reason])
+    }
+    
+    func testDecideReasons_forcedVariationFound() {
+        let featureKey = "feature_1"
+        let variationKey = "b"
+        let experimentKey = setForcedVariationForFeatureTest(featureKey: featureKey, userId: kUserId, variationKey: variationKey)
+
+        let decision = user.decide(key: featureKey, options: [.includeReasons])
+        XCTAssertEqual(decision.variationKey, variationKey)
+        XCTAssertEqual(decision.reasons, [LogMessage.userHasForcedVariation(kUserId, experimentKey, variationKey).reason])
+    }
+    
+    func testDecideReasons_forcedVariationFoundButInvalid() {
+        let featureKey = "feature_1"
+        let variationKey = "b"
+        let experimentKey = setForcedVariationForFeatureTest(featureKey: featureKey, userId: kUserId, variationKey: variationKey)
+        // remove all variations after setting forced variations
+        removeVariationsForFeatureTest(featureKey: featureKey, userId: kUserId, variationKey: variationKey)
+        
+        let decision = user.decide(key: featureKey, options: [.includeReasons])
+        XCTAssertNotEqual(decision.variationKey, variationKey)
+        XCTAssert(decision.reasons.contains(LogMessage.userHasForcedVariationButInvalid(kUserId, experimentKey).reason))
+    }
+    
+    func testDecideReasons_whiteListVariationFound() {
+        let featureKey = "feature_1"
+        let variationKey = "b"
+        setWhiteListForFeatureTest(featureKey: featureKey, userId: kUserId, variationKey: variationKey)
+
+        let decision = user.decide(key: featureKey, options: [.includeReasons])
+        XCTAssertEqual(decision.variationKey, variationKey)
+        XCTAssertEqual(decision.reasons, [LogMessage.forcedVariationFound(variationKey, kUserId).reason])
+    }
+    
+    func testDecideReasons_whiteListVariationFoundButInvalid() {
+        let featureKey = "feature_1"
+        let variationKey = "invalid-key"
+        setWhiteListForFeatureTest(featureKey: featureKey, userId: kUserId, variationKey: variationKey)
+
+        let decision = user.decide(key: featureKey, options: [.includeReasons])
+        XCTAssertNotEqual(decision.variationKey, variationKey)
+        XCTAssert(decision.reasons.contains(LogMessage.forcedVariationFoundButInvalid(variationKey, kUserId).reason))
+    }
+
+    func testDecideReasons_userMeetsConditionsForTargetingRule() {
+        let key = "feature_1"
+        
+        user.setAttribute(key: "country", value: "US")
+        var decision = user.decide(key: key)
+        XCTAssert(decision.reasons.isEmpty)
+        decision = user.decide(key: key, options: [.includeReasons])
+        XCTAssert(decision.reasons.contains(LogMessage.userMeetsConditionsForTargetingRule(kUserId, 1).reason))
+    }
+    
+    func testDecideReasons_userDoesntMeetConditionsForTargetingRule() {
+        let key = "feature_1"
+        
+        user.setAttribute(key: "country", value: "CA")
+        var decision = user.decide(key: key)
+        XCTAssert(decision.reasons.isEmpty)
+        decision = user.decide(key: key, options: [.includeReasons])
+        XCTAssert(decision.reasons.contains(LogMessage.userDoesntMeetConditionsForTargetingRule(kUserId, 1).reason))
+    }
+    
+    func testDecideReasons_userBucketedIntoTargetingRule() {
+        let key = "feature_1"
+        
+        user.setAttribute(key: "country", value: "US")
+        var decision = user.decide(key: key)
+        XCTAssert(decision.reasons.isEmpty)
+        decision = user.decide(key: key, options: [.includeReasons])
+        XCTAssert(decision.reasons.contains(LogMessage.userBucketedIntoTargetingRule(kUserId, 1).reason))
+    }
+    
+    func testDecideReasons_userBucketedIntoEveryoneTargetingRule() {
+        let key = "feature_1"
+        
+        user.setAttribute(key: "country", value: "KO")
+        var decision = user.decide(key: key)
+        XCTAssert(decision.reasons.isEmpty)
+        decision = user.decide(key: key, options: [.includeReasons])
+        XCTAssert(decision.reasons.contains(LogMessage.userBucketedIntoEveryoneTargetingRule(kUserId).reason))
+    }
+    
+    func testDecideReasons_userNotBucketedIntoTargetingRule() {
+        let key = "feature_1"
+        
+        user.setAttribute(key: "browser", value: "safari")
+        var decision = user.decide(key: key)
+        XCTAssert(decision.reasons.isEmpty)
+        decision = user.decide(key: key, options: [.includeReasons])
+        XCTAssert(decision.reasons.contains(LogMessage.userNotBucketedIntoTargetingRule(kUserId, 2).reason))
+    }
+        
+    func testDecideReasons_userBucketedIntoVariationInExperiment() {
+        let featureKey = "feature_2"        // embedding experiment: "exp_no_audience"
+        let experimentKey = "exp_no_audience"
+        let variationKey = "variation_with_traffic"
+        
+        var decision = user.decide(key: featureKey)
+        XCTAssert(decision.reasons.isEmpty)
+        decision = user.decide(key: featureKey, options: [.ignoreUserProfileService, .includeReasons])
+        XCTAssert(decision.reasons.contains(LogMessage.userBucketedIntoVariationInExperiment(kUserId,
+                                                                                             experimentKey,
+                                                                                             variationKey).reason))
+    }
+    
+    func testDecideReasons_userNotBucketedIntoVariation() {
+        let featureKey = "feature_2"        // embedding experiment: "exp_no_audience"
+        let experimentId = "10420810910"    // "exp_no_audience"
+
+        var experiment = optimizely.config!.getExperiment(id: experimentId)!
+        var trafficAllocation = experiment.trafficAllocation[0]
+        trafficAllocation.endOfRange = 0
+        experiment.trafficAllocation = [trafficAllocation]
+        optimizely.config!.experimentIdMap = [experimentId: experiment]
+
+        var decision = user.decide(key: featureKey)
+        XCTAssert(decision.reasons.isEmpty)
+        decision = user.decide(key: featureKey, options: [.includeReasons])
+        XCTAssert(decision.reasons.contains(LogMessage.userNotBucketedIntoVariation(kUserId).reason))
+    }
+    
+    func testDecideReasons_userBucketedIntoInvalidVariation() {
+        let featureKey = "feature_2"        // embedding experiment: "exp_no_audience"
+        let experimentId = "10420810910"    // "exp_no_audience"
+        let variationKey = "variation_with_traffic"
+        let variationIdCorrect = "10418551353"
+        let variationIdInvalid = "invalid"
+        
+        var experiment = optimizely.config!.getExperiment(id: experimentId)!
+        var variation = experiment.getVariation(key: variationKey)!
+        variation.id = variationIdInvalid
+        experiment.variations = [variation]
+        optimizely.config!.experimentIdMap = [experimentId: experiment]
+
+        var decision = user.decide(key: featureKey)
+        XCTAssert(decision.reasons.isEmpty)
+        decision = user.decide(key: featureKey, options: [.includeReasons])
+        XCTAssert(decision.reasons.contains(LogMessage.userBucketedIntoInvalidVariation(variationIdCorrect).reason))
+    }
+    
+    func testDecideReasons_userBucketedIntoExperimentInGroup() {
+        let featureKey = "feature_3"
+        let experimentKey = "group_exp_1"
+        let groupId = "13142870430"
+        setExperimentForFeatureTest(featureKey: featureKey, experimentKey: experimentKey)
+
+        let decision = user.decide(key: featureKey, options: [.ignoreUserProfileService, .includeReasons])
+        XCTAssert(decision.reasons.contains(LogMessage.userBucketedIntoExperimentInGroup(kUserId,
+                                                                                         experimentKey,
+                                                                                         groupId).reason))
+    }
+    
+    func testDecideReasons_userNotBucketedIntoExperimentInGroup() {
+        let featureKey = "feature_3"
+        let experimentKey = "group_exp_2"
+        let groupId = "13142870430"
+        setExperimentForFeatureTest(featureKey: featureKey, experimentKey: experimentKey)
+
+        let decision = user.decide(key: featureKey, options: [.includeReasons])
+        XCTAssert(decision.reasons.contains(LogMessage.userNotBucketedIntoExperimentInGroup(kUserId,
+                                                                                            experimentKey,
+                                                                                            groupId).reason))
+    }
+    
+    func testDecideReasons_userNotBucketedIntoAnyExperimentInGroup() {
+        let featureKey = "feature_3"
+        let experimentKey = "group_exp_1"
+        let groupId = "13142870430"
+        setExperimentForFeatureTest(featureKey: featureKey, experimentKey: experimentKey)
+
+        var group = optimizely.config!.getGroup(id: groupId)!
+        group.trafficAllocation = []
+        optimizely.config!.project.groups = [group]
+
+        let decision = user.decide(key: featureKey, options: [.includeReasons])
+        XCTAssert(decision.reasons.contains(LogMessage.userNotBucketedIntoAnyExperimentInGroup(kUserId,
+                                                                                               groupId).reason))
+    }
+    
+    func testDecideReasons_userBucketedIntoInvalidExperiment() {
+        let featureKey = "feature_3"
+        let experimentKey = "group_exp_1"
+        let groupId = "13142870430"
+        setExperimentForFeatureTest(featureKey: featureKey, experimentKey: experimentKey)
+
+        let experimentIdInvalid = "invalid"
+
+        var group = optimizely.config!.getGroup(id: groupId)!
+        var trafficAllocation = group.trafficAllocation[0]
+        trafficAllocation.entityId = experimentIdInvalid
+        group.trafficAllocation = [trafficAllocation]
+        optimizely.config!.project.groups = [group]
+
+        let decision = user.decide(key: featureKey, options: [.includeReasons])
+        XCTAssert(decision.reasons.contains(LogMessage.userBucketedIntoInvalidExperiment(experimentIdInvalid).reason))
+    }
+    
+    func testDecideReasons_userNotInExperiment() {
+        let featureKey = "feature_1"
+        let experimentKey = "exp_with_audience"
+        
+        let decision = user.decide(key: featureKey, options: [.includeReasons])
+        XCTAssert(decision.reasons.contains(LogMessage.userNotInExperiment(kUserId, experimentKey).reason))
+    }
+        
+}
+
+// Utils
+
+extension OptimizelyUserContextTests_Decide_Reasons {
+
+    func setAudienceForFeatureTest(featureKey: String, audienceId: String) {
+        let experimentId = "10390977673"    // "exp_with_audience"
+        var experiment = optimizely.config!.getExperiment(id: experimentId)!
+        experiment.audienceIds = [audienceId]
+        optimizely.config!.experimentIdMap = [experimentId: experiment]
+    }
+    
+    func setStatusForFeatureTest(featureKey: String, status: Experiment.Status) {
+        let experimentId = "10390977673"    // "exp_with_audience"
+        var experiment = optimizely.config!.getExperiment(id: experimentId)!
+        experiment.status = status
+        optimizely.config!.experimentIdMap = [experimentId: experiment]
+    }
+    
+    func setForcedVariationForFeatureTest(featureKey: String, userId: String, variationKey: String) -> String {
+        let experimentId = "10390977673"    // "exp_with_audience"
+        let experiment = optimizely.config!.getExperiment(id: experimentId)!
+        _ = optimizely.setForcedVariation(experimentKey: experiment.key, userId: userId, variationKey: variationKey)
+        return experiment.key
+    }
+
+    func removeVariationsForFeatureTest(featureKey: String, userId: String, variationKey: String) {
+        let experimentId = "10390977673"    // "exp_with_audience"
+        var experiment = optimizely.config!.getExperiment(id: experimentId)!
+        experiment.variations = []
+        optimizely.config!.experimentIdMap = [experimentId: experiment]
+        optimizely.config!.experimentKeyMap = [experiment.key: experiment]
+    }
+
+    func setWhiteListForFeatureTest(featureKey: String, userId: String, variationKey: String) {
+        let experimentId = "10390977673"    // "exp_with_audience"
+        var experiment = optimizely.config!.getExperiment(id: experimentId)!
+        experiment.forcedVariations = [userId: variationKey]
+        optimizely.config!.experimentIdMap = [experimentId: experiment]
+    }
+
+    func setExperimentForFeatureTest(featureKey: String, experimentKey: String) {
+        let experimentId = optimizely.config!.getExperimentId(key: experimentKey)!
+        var feature = optimizely.config!.getFeatureFlag(key: featureKey)!
+        feature.experimentIds = [experimentId]
+        optimizely.config!.featureFlagKeyMap = [featureKey: feature]
+    }
+
+}
+
diff --git a/Tests/OptimizelyTests-Common/OptimizelyUserContextTests_Objc.m b/Tests/OptimizelyTests-Common/OptimizelyUserContextTests_Objc.m
new file mode 100644
index 000000000..13b788860
--- /dev/null
+++ b/Tests/OptimizelyTests-Common/OptimizelyUserContextTests_Objc.m
@@ -0,0 +1,228 @@
+/****************************************************************************
+* Copyright 2021, Optimizely, Inc. and contributors                        *
+*                                                                          *
+* Licensed under the Apache License, Version 2.0 (the "License");          *
+* you may not use this file except in compliance with the License.         *
+* You may obtain a copy of the License at                                  *
+*                                                                          *
+*    http://www.apache.org/licenses/LICENSE-2.0                            *
+*                                                                          *
+* Unless required by applicable law or agreed to in writing, software      *
+* distributed under the License is distributed on an "AS IS" BASIS,        *
+* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. *
+* See the License for the specific language governing permissions and      *
+* limitations under the License.                                           *
+***************************************************************************/
+
+#import <XCTest/XCTest.h>
+#import <OCMock/OCMock.h>
+@import Optimizely;
+
+static NSString * const kUserId = @"tester";
+static NSString * const kSdkKey = @"12345";
+static NSString * datafile;
+
+@interface OptimizelyUserContextTests_Objc : XCTestCase
+@property(nonatomic) OptimizelyClient *optimizely;
+@end
+
+@implementation OptimizelyUserContextTests_Objc
+
+- (void)setUp {
+    NSString *filePath = [[NSBundle bundleForClass:self.class] pathForResource:@"decide_datafile" ofType:@"json"];
+    datafile = [NSString stringWithContentsOfFile:filePath encoding:NSUTF8StringEncoding error:nil];
+    
+    self.optimizely = [[OptimizelyClient alloc] initWithSdkKey: kSdkKey];
+    [self.optimizely startWithDatafile:datafile error:nil];
+}
+
+// MARK: - UserContext
+
+- (void)testUserContext {
+    OptimizelyUserContext *user = [[OptimizelyUserContext alloc] initWithOptimizely:self.optimizely
+                                                                             userId:kUserId
+                                                                         attributes:nil];
+    XCTAssert([user.optimizely isEqual:self.optimizely]);
+    XCTAssert([user.userId isEqualToString:kUserId]);
+    XCTAssert(user.attributes.count == 0);
+    
+    user = [[OptimizelyUserContext alloc] initWithOptimizely:self.optimizely
+                                                      userId:kUserId
+                                              attributes:@{@"country": @"US", @"age": @"18"}];
+    XCTAssert([user.optimizely isEqual:self.optimizely]);
+    XCTAssert([user.userId isEqualToString:kUserId]);
+    XCTAssert([user.attributes[@"country"] isEqualToString:@"US"]);
+    XCTAssert([user.attributes[@"age"] isEqualToString:@"18"]);
+}
+
+- (void)testCreateUserContext {
+    OptimizelyUserContext *user = [self.optimizely createUserContextWithUserId:kUserId attributes:@{@"country": @"US", @"age": @"18"}];
+    
+    XCTAssert([user.optimizely isEqual:self.optimizely]);
+    XCTAssert([user.userId isEqualToString:kUserId]);
+    XCTAssert([user.attributes[@"country"] isEqualToString:@"US"]);
+    XCTAssert([user.attributes[@"age"] isEqualToString:@"18"]);
+}
+
+- (void)testUserContext_setAttribute {
+    OptimizelyUserContext *user = [self.optimizely createUserContextWithUserId:kUserId attributes:nil];
+    [user setAttributeWithKey:@"country" value:@"US"];
+    [user setAttributeWithKey:@"age" value:@"18"];
+
+    XCTAssert([user.optimizely isEqual:self.optimizely]);
+    XCTAssert([user.userId isEqualToString:kUserId]);
+    XCTAssert([user.attributes[@"country"] isEqualToString:@"US"]);
+    XCTAssert([user.attributes[@"age"] isEqualToString:@"18"]);
+}
+
+// MARK: - decide
+
+- (void)testDecide {
+    OptimizelyUserContext *user = [self.optimizely createUserContextWithUserId:kUserId attributes:nil];
+
+    NSString *featureKey = @"feature_2";
+    OptimizelyDecision *decision = [user decideWithKey:featureKey options:nil];
+
+    XCTAssert([decision.variationKey isEqualToString:@"variation_with_traffic"]);
+    XCTAssertTrue(decision.enabled);
+    XCTAssertNotNil(decision.variables);
+    NSDictionary *variables = [decision.variables toMap];
+    XCTAssert([variables[@"i_42"] intValue] == 42);
+    XCTAssert([decision.ruleKey isEqualToString:@"exp_no_audience"]);
+    XCTAssert([decision.flagKey isEqualToString:featureKey]);
+    XCTAssert([decision.userContext.userId isEqualToString:kUserId]);
+    XCTAssert(decision.reasons.count == 0);
+}
+
+- (void)testDecide_reasons {
+    // new optimizely instance not started yet (SDK not ready)
+    self.optimizely = [[OptimizelyClient alloc] initWithSdkKey: kSdkKey];
+
+    OptimizelyUserContext *user = [self.optimizely createUserContextWithUserId:kUserId attributes:nil];
+
+    NSString *featureKey = @"feature_2";
+    OptimizelyDecision *decision = [user decideWithKey:featureKey options:nil];
+
+    XCTAssertNil(decision.variationKey);
+    XCTAssertFalse(decision.enabled);
+    XCTAssertTrue([decision.variables isEmpty]);
+    XCTAssertNil(decision.ruleKey);
+    XCTAssert([decision.flagKey isEqualToString:featureKey]);
+    XCTAssert([decision.userContext.userId isEqualToString:kUserId]);
+    XCTAssert(decision.reasons.count == 1);
+    XCTAssert([decision.reasons[0] isEqualToString:@"Optimizely SDK not configured properly yet."]);
+}
+
+//// MARK: - decideAll
+
+- (void)testDecideAll_allFeatures {
+    NSString *featureKey1 = @"feature_1";
+    NSString *featureKey2 = @"feature_2";
+    NSString *featureKey3 = @"feature_3";
+
+    OptimizelyUserContext *user = [self.optimizely createUserContextWithUserId:kUserId attributes:@{@"gender": @"f"}];
+
+    NSDictionary<NSString*,OptimizelyDecision*> *decisions = [user decideAllWithOptions:nil];
+            
+    XCTAssert(decisions.count == 3);
+    XCTAssertTrue(decisions[featureKey1].enabled);
+    XCTAssertTrue(decisions[featureKey2].enabled);
+    XCTAssertFalse(decisions[featureKey3].enabled);
+}
+
+//// MARK: - decideForKeys
+
+- (void)testDecideAll_twoFeatures {
+    NSString *featureKey1 = @"feature_1";
+    NSString *featureKey2 = @"feature_2";
+
+    OptimizelyUserContext *user = [self.optimizely createUserContextWithUserId:kUserId attributes:@{@"gender": @"f"}];
+
+    NSDictionary<NSString*,OptimizelyDecision*> *decisions;
+    decisions = [user decideWithKeys:@[featureKey1, featureKey2] options:nil];
+    
+    XCTAssert(decisions.count == 2);
+    XCTAssertTrue(decisions[featureKey1].enabled);
+    XCTAssertTrue(decisions[featureKey2].enabled);
+}
+
+
+// MARK: - OptimizelyDecideOptions
+
+- (void)testDecide_options {
+    OptimizelyUserContext *user = [self.optimizely createUserContextWithUserId:kUserId attributes:@{@"gender": @"f"}];
+
+    // array of NSNumber for OptimizelyDecideOption objc type (do not use integer directly since it may change)
+    NSArray *optionsInObjcFormat = @[@(OptimizelyDecideOptionEnabledFlagsOnly)];
+    NSDictionary<NSString*,OptimizelyDecision*> *decisions1 = [user decideAllWithOptions:nil];
+    
+    XCTAssert(decisions1.count == 3);
+    XCTAssertTrue(decisions1[@"feature_1"].enabled);
+    XCTAssertTrue(decisions1[@"feature_2"].enabled);
+    XCTAssertFalse(decisions1[@"feature_3"].enabled);
+
+    NSDictionary<NSString*,OptimizelyDecision*> *decisions2 = [user decideAllWithOptions:optionsInObjcFormat];
+    XCTAssert(decisions2.count == 2);
+    XCTAssertTrue(decisions2[@"feature_1"].enabled);
+    XCTAssertTrue(decisions2[@"feature_2"].enabled);
+}
+
+- (void)testDecide_defaultOptions {
+    OptimizelyUserContext *user = [self.optimizely createUserContextWithUserId:kUserId attributes:@{@"gender": @"f"}];
+    NSDictionary<NSString*,OptimizelyDecision*> *decisions1 = [user decideAllWithOptions:nil];
+    
+    XCTAssert(decisions1.count == 3);
+    XCTAssertTrue(decisions1[@"feature_1"].enabled);
+    XCTAssertTrue(decisions1[@"feature_2"].enabled);
+    XCTAssertFalse(decisions1[@"feature_3"].enabled);
+
+    // array of NSNumber for OptimizelyDecideOption objc type (do not use integer directly since it may change)
+    NSArray *defaultOptionsInObjcFormat = @[@(OptimizelyDecideOptionEnabledFlagsOnly)];
+    OptimizelyClient *newOtimizely = [[OptimizelyClient alloc] initWithSdkKey:kSdkKey
+                                                                       logger:nil
+                                                              eventDispatcher:nil
+                                                           userProfileService:nil
+                                                     periodicDownloadInterval:0
+                                                              defaultLogLevel:OptimizelyLogLevelDebug
+                                                         defaultDecideOptions:defaultOptionsInObjcFormat];
+    [newOtimizely startWithDatafile:datafile error:nil];
+
+    user = [newOtimizely createUserContextWithUserId:kUserId attributes:@{@"gender": @"f"}];
+    NSDictionary<NSString*,OptimizelyDecision*> *decisions2 = [user decideAllWithOptions:nil];
+    
+    XCTAssert(decisions2.count == 2);
+    XCTAssertTrue(decisions2[@"feature_1"].enabled);
+    XCTAssertTrue(decisions2[@"feature_2"].enabled);
+}
+
+// MARK: - legacy APIs with UserContext
+
+- (void)testTrackWithUserContext {
+    id<OPTEventDispatcher> mockEventDispatcher = [self injectMockEventDispatcher];
+    OCMExpect([mockEventDispatcher dispatchEventWithEvent:[OCMArg isNotNil]
+                                        completionHandler:nil]);
+
+    OptimizelyUserContext *user = [self.optimizely createUserContextWithUserId:kUserId attributes:@{@"gender": @"f"}];
+
+    NSError *error = nil;
+    BOOL status = [user trackEventWithEventKey:@"event1" eventTags:nil error:&error];
+
+    XCTAssertTrue(status);
+    OCMVerifyAllWithDelay(mockEventDispatcher, 1.0);   // event-dispatch non-blocking
+}
+
+// MARK: - Utils
+
+- (id<OPTEventDispatcher>)injectMockEventDispatcher {
+    id<OPTEventDispatcher>  mockEventDispatcher = OCMClassMock([DefaultEventDispatcher class]);
+    self.optimizely = [[OptimizelyClient alloc] initWithSdkKey:[NSString stringWithFormat:@"%d", arc4random()]
+                                                        logger:nil
+                                               eventDispatcher:mockEventDispatcher
+                                            userProfileService:nil
+                                      periodicDownloadInterval:0
+                                               defaultLogLevel:OptimizelyLogLevelDebug];
+    [self.optimizely startWithDatafile:datafile error:nil];
+    return mockEventDispatcher;
+}
+
+@end
diff --git a/Tests/OptimizelyTests-DataModel/ProjectConfigTests.swift b/Tests/OptimizelyTests-DataModel/ProjectConfigTests.swift
index 621084e78..3aff4aa89 100644
--- a/Tests/OptimizelyTests-DataModel/ProjectConfigTests.swift
+++ b/Tests/OptimizelyTests-DataModel/ProjectConfigTests.swift
@@ -1,6 +1,6 @@
 //
 /****************************************************************************
-* Copyright 2019, Optimizely, Inc. and contributors                        *
+* Copyright 2019,2021, Optimizely, Inc. and contributors                   *
 *                                                                          *
 * Licensed under the Apache License, Version 2.0 (the "License");          *
 * you may not use this file except in compliance with the License.         *
@@ -90,7 +90,7 @@ extension ProjectConfigTests {
     
     
     func testGetForcedVariation_InvalidExperimentKey() {
-        let variationKey = config.getForcedVariation(experimentKey: "invalid_key", userId: "user")
+        let variationKey = config.getForcedVariation(experimentKey: "invalid_key", userId: "user").result
         XCTAssertNil(variationKey)
     }
     
@@ -109,7 +109,7 @@ extension ProjectConfigTests {
         config.experimentKeyMap[experimentKey] = experiment
         
         // forced variation finds variation which is not valid any more
-        let variationKey = config.getForcedVariation(experimentKey: experimentKey, userId: userId)
+        let variationKey = config.getForcedVariation(experimentKey: experimentKey, userId: userId).result
         XCTAssertNil(variationKey)
     }
 
@@ -134,12 +134,12 @@ extension ProjectConfigTests {
 
         var result = config.setForcedVariation(experimentKey: experimentKey, userId: userId, variationKey: "a")
         XCTAssert(result)
-        var variation = config.getForcedVariation(experimentKey: experimentKey, userId: userId)!
+        var variation = config.getForcedVariation(experimentKey: experimentKey, userId: userId).result!
         XCTAssertEqual(variation.key, "a")
 
         result = config.setForcedVariation(experimentKey: experimentKey, userId: userId, variationKey: "b")
         XCTAssert(result)
-        variation = config.getForcedVariation(experimentKey: experimentKey, userId: userId)!
+        variation = config.getForcedVariation(experimentKey: experimentKey, userId: userId).result!
         XCTAssertEqual(variation.key, "b")
     }
 
diff --git a/Tests/TestData/decide/decide_datafile.json b/Tests/TestData/decide/decide_datafile.json
new file mode 100644
index 000000000..eb7b0f802
--- /dev/null
+++ b/Tests/TestData/decide/decide_datafile.json
@@ -0,0 +1,346 @@
+{
+  "version": "4",
+  "sendFlagDecisions": true,
+  "rollouts": [
+    {
+      "experiments": [
+        {
+          "audienceIds": ["13389130056"],
+          "forcedVariations": {},
+          "id": "3332020515",
+          "key": "3332020515",
+          "layerId": "3319450668",
+          "status": "Running",
+          "trafficAllocation": [
+            {
+              "endOfRange": 10000,
+              "entityId": "3324490633"
+            }
+          ],
+          "variations": [
+            {
+              "featureEnabled": true,
+              "id": "3324490633",
+              "key": "3324490633",
+              "variables": []
+            }
+          ]
+        },
+        {
+          "audienceIds": ["12208130097"],
+          "forcedVariations": {},
+          "id": "3332020494",
+          "key": "3332020494",
+          "layerId": "3319450668",
+          "status": "Running",
+          "trafficAllocation": [
+            {
+              "endOfRange": 0,
+              "entityId": "3324490562"
+            }
+          ],
+          "variations": [
+            {
+              "featureEnabled": true,
+              "id": "3324490562",
+              "key": "3324490562",
+              "variables": []
+            }
+          ]
+        },
+        {
+            "status": "Running",
+            "audienceIds": [],
+            "variations": [
+                {
+                    "variables": [],
+                    "id": "18257766532",
+                    "key": "18257766532",
+                    "featureEnabled": true
+                }
+            ],
+            "id": "18322080788",
+            "key": "18322080788",
+            "layerId": "18263344648",
+            "trafficAllocation": [
+                {
+                    "entityId": "18257766532",
+                    "endOfRange": 10000
+                }
+            ],
+            "forcedVariations": { }
+        }
+      ],
+      "id": "3319450668"
+    }
+  ],
+  "anonymizeIP": true,
+  "botFiltering": true,
+  "projectId": "10431130345",
+  "variables": [],
+  "featureFlags": [
+      {
+          "experimentIds": ["10390977673"],
+          "id": "4482920077",
+          "key": "feature_1",
+          "rolloutId": "3319450668",
+          "variables": [
+              {
+                  "defaultValue": "42",
+                  "id": "2687470095",
+                  "key": "i_42",
+                  "type": "integer"
+              },
+              {
+                  "defaultValue": "4.2",
+                  "id": "2689280165",
+                  "key": "d_4_2",
+                  "type": "double"
+              },
+              {
+                  "defaultValue": "true",
+                  "id": "2689660112",
+                  "key": "b_true",
+                  "type": "boolean"
+              },
+              {
+                  "defaultValue": "foo",
+                  "id": "2696150066",
+                  "key": "s_foo",
+                  "type": "string"
+              },
+              {
+                  "defaultValue": "{\"value\":1}",
+                  "id": "2696150067",
+                  "key": "j_1",
+                  "type": "string",
+                  "subType": "json"
+              },
+              {
+                  "defaultValue": "invalid",
+                  "id": "2696150068",
+                  "key": "i_1",
+                  "type": "invalid",
+                  "subType": ""
+              }
+          ]
+      },
+      {
+          "experimentIds": ["10420810910"],
+          "id": "4482920078",
+          "key": "feature_2",
+          "rolloutId": "",
+          "variables": [
+              {
+                  "defaultValue": "42",
+                  "id": "2687470095",
+                  "key": "i_42",
+                  "type": "integer"
+              }
+          ]
+      },
+      {
+          "experimentIds": [],
+          "id": "44829230000",
+          "key": "feature_3",
+          "rolloutId": "",
+          "variables": []
+      }
+  ],
+  "experiments": [
+    {
+      "status": "Running",
+      "key": "exp_with_audience",
+      "layerId": "10420273888",
+      "trafficAllocation": [
+        {
+          "entityId": "10389729780",
+          "endOfRange": 10000
+        }
+      ],
+      "audienceIds": ["13389141123"],
+      "variations": [
+        {
+          "variables": [],
+          "featureEnabled": true,
+          "id": "10389729780",
+          "key": "a"
+        },
+        {
+          "variables": [],
+          "id": "10416523121",
+          "key": "b"
+        }
+      ],
+      "forcedVariations": {},
+      "id": "10390977673"
+    },
+    {
+      "status": "Running",
+      "key": "exp_no_audience",
+      "layerId": "10417730432",
+      "trafficAllocation": [
+        {
+          "entityId": "10418551353",
+          "endOfRange": 10000
+        }
+      ],
+      "audienceIds": [],
+      "variations": [
+        {
+          "variables": [],
+          "featureEnabled": true,
+          "id": "10418551353",
+          "key": "variation_with_traffic"
+        },
+        {
+          "variables": [],
+          "featureEnabled": false,
+          "id": "10418510624",
+          "key": "variation_no_traffic"
+        }
+      ],
+      "forcedVariations": {},
+      "id": "10420810910"
+    }
+  ],
+  "audiences": [
+      {
+          "id": "13389141123",
+          "conditions": "[\"and\", [\"or\", [\"or\", {\"match\": \"exact\", \"name\": \"gender\", \"type\": \"custom_attribute\", \"value\": \"f\"}]]]",
+          "name": "gender"
+      },
+      {
+          "id": "13389130056",
+          "conditions": "[\"and\", [\"or\", [\"or\", {\"match\": \"exact\", \"name\": \"country\", \"type\": \"custom_attribute\", \"value\": \"US\"}]]]",
+          "name": "US"
+      },
+      {
+          "id": "12208130097",
+          "conditions": "[\"and\", [\"or\", [\"or\", {\"match\": \"exact\", \"name\": \"browser\", \"type\": \"custom_attribute\", \"value\": \"safari\"}]]]",
+          "name": "safari"
+      },
+      {
+          "id": "age_18",
+          "conditions": "[\"and\", [\"or\", [\"or\", {\"match\": \"gt\", \"name\": \"age\", \"type\": \"custom_attribute\", \"value\": 18}]]]",
+          "name": "age_18"
+      },
+      {
+          "id": "invalid_format",
+          "conditions": "[]",
+          "name": "invalid_format"
+      },
+      {
+          "id": "invalid_condition",
+          "conditions": "[\"and\", [\"or\", [\"or\", {\"match\": \"gt\", \"name\": \"age\", \"type\": \"custom_attribute\", \"value\": \"US\"}]]]",
+          "name": "invalid_condition"
+      },
+      {
+          "id": "invalid_type",
+          "conditions": "[\"and\", [\"or\", [\"or\", {\"match\": \"gt\", \"name\": \"age\", \"type\": \"invalid\", \"value\": 18}]]]",
+          "name": "invalid_type"
+      },
+      {
+          "id": "invalid_match",
+          "conditions": "[\"and\", [\"or\", [\"or\", {\"match\": \"invalid\", \"name\": \"age\", \"type\": \"custom_attribute\", \"value\": 18}]]]",
+          "name": "invalid_match"
+      },
+      {
+          "id": "nil_value",
+          "conditions": "[\"and\", [\"or\", [\"or\", {\"match\": \"gt\", \"name\": \"age\", \"type\": \"custom_attribute\"}]]]",
+          "name": "nil_value"
+      },
+      {
+          "id": "invalid_name",
+          "conditions": "[\"and\", [\"or\", [\"or\", {\"match\": \"gt\", \"type\": \"custom_attribute\", \"value\": 18}]]]",
+          "name": "invalid_name"
+      }
+  ],
+  "groups": [
+      {
+          "policy": "random",
+          "trafficAllocation": [
+              {
+                  "entityId": "10390965532",
+                  "endOfRange": 10000
+              }
+          ],
+          "experiments": [
+              {
+                  "status": "Running",
+                  "key": "group_exp_1",
+                  "layerId": "10420222423",
+                  "trafficAllocation": [
+                      {
+                          "entityId": "10389752311",
+                          "endOfRange": 10000
+                      }
+                  ],
+                  "audienceIds": [],
+                  "variations": [
+                      {
+                          "variables": [],
+                          "featureEnabled": false,
+                          "id": "10389752311",
+                          "key": "a"
+                      }
+                  ],
+                  "forcedVariations": {},
+                  "id": "10390965532"
+              },
+              {
+                  "status": "Running",
+                  "key": "group_exp_2",
+                  "layerId": "10417730432",
+                  "trafficAllocation": [
+                      {
+                          "entityId": "10418524243",
+                          "endOfRange": 10000
+                      }
+                  ],
+                  "audienceIds": [],
+                  "variations": [
+                      {
+                          "variables": [],
+                          "featureEnabled": false,
+                          "id": "10418524243",
+                          "key": "a"
+                      }
+                  ],
+                  "forcedVariations": {},
+                  "id": "10420843432"
+              }
+          ],
+          "id": "13142870430"
+      }
+  ],
+  "attributes": [
+      {
+          "id": "10401066117",
+          "key": "gender"
+      },
+      {
+          "id": "10401066170",
+          "key": "testvar"
+      }
+  ],
+  "accountId": "10367498574",
+  "events": [
+    {
+      "experimentIds": [
+        "10420810910"
+      ],
+      "id": "10404198134",
+      "key": "event1"
+    },
+    {
+      "experimentIds": [
+        "10420810910",
+        "10390977673"
+      ],
+      "id": "10404198135",
+      "key": "event_multiple_running_exp_attached"
+    }
+  ],
+  "revision": "241"
+}
diff --git a/Tests/TestUtils/OTUtils.swift b/Tests/TestUtils/OTUtils.swift
index 3fe484d02..1ad958bb8 100644
--- a/Tests/TestUtils/OTUtils.swift
+++ b/Tests/TestUtils/OTUtils.swift
@@ -1,5 +1,5 @@
 /****************************************************************************
-* Copyright 2019, Optimizely, Inc. and contributors                        *
+* Copyright 2019,2021, Optimizely, Inc. and contributors                   *
 *                                                                          *
 * Licensed under the Apache License, Version 2.0 (the "License");          *
 * you may not use this file except in compliance with the License.         *
@@ -137,6 +137,31 @@ class OTUtils {
             return nil
         }
     }
+    
+    // MARK: - UPS
+    
+    static func getVariationFromUPS(ups: OPTUserProfileService, userId: String, experimentId: String) -> String? {
+        if let profile = ups.lookup(userId: userId),
+            let bucketMap = profile[UserProfileKeys.kBucketMap] as? OPTUserProfileService.UPBucketMap,
+            let experimentMap = bucketMap[experimentId],
+            let variationId = experimentMap[UserProfileKeys.kVariationId] {
+            return variationId
+        } else {
+            return nil
+        }
+    }
+    
+    static func setVariationToUPS(ups: OPTUserProfileService, userId: String, experimentId: String, variationId: String){
+        var profile = ups.lookup(userId: userId) ?? OPTUserProfileService.UPProfile()
+        
+        var bucketMap = profile[UserProfileKeys.kBucketMap] as? OPTUserProfileService.UPBucketMap ?? OPTUserProfileService.UPBucketMap()
+        bucketMap[experimentId] = [UserProfileKeys.kVariationId: variationId]
+        
+        profile[UserProfileKeys.kBucketMap] = bucketMap
+        profile[UserProfileKeys.kUserId] = userId
+        
+        ups.save(userProfile: profile)
+    }
 
     // MARK: - big numbers