fix(ios): correct size when changing size programmatically

example/src/screens/MapScreen.tsx

@@ -58,11 +58,7 @@ export const MapScreen = () => {
     })),
   ]
 
-  const handlePresent = (sizeInfo: SizeInfo) => {
-    buttonY.value = withSpring(-sizeInfo.value, SPRING_CONFIG)
-  }
-
-  const handleSizeChange = (sizeInfo: SizeInfo) => {
+  const animateButton = (sizeInfo: SizeInfo) => {
     buttonY.value = withSpring(-sizeInfo.value, SPRING_CONFIG)
   }
 
@@ -96,9 +92,9 @@ export const MapScreen = () => {
         cornerRadius={12}
         initialIndex={1}
         onDragChange={dragChangeHandler}
-        onPresent={(e) => handlePresent(e.nativeEvent)}
-        onSizeChange={(e) => handleSizeChange(e.nativeEvent)}
-        // onDragEnd={(e) => handleSizeChange(e.nativeEvent)}
+        onPresent={(e) => animateButton(e.nativeEvent)}
+        onSizeChange={(e) => animateButton(e.nativeEvent)}
+        onDragEnd={(e) => animateButton(e.nativeEvent)}
         // initialIndexAnimated={false}
         onMount={() => {
           // sheetRef.current?.present(1)

ios/TrueSheetView.swift

@@ -230,13 +230,28 @@ class TrueSheetView: UIView, RCTInvalidating, TrueSheetViewControllerDelegate {
     }
 
     viewController.maxHeight = maxHeight
-    configurePresentedSheet()
+
+    if #available(iOS 15.0, *) {
+      withPresentedSheet { _ in
+        viewController.setupSizes()
+      }
+    }
   }
 
   @objc
   func setContentHeight(_ height: NSNumber) {
-    viewController.setContentHeight(CGFloat(height.floatValue))
-    configurePresentedSheet()
+    let contentHeight = CGFloat(height.floatValue)
+    guard viewController.contentHeight != contentHeight else {
+      return
+    }
+
+    viewController.contentHeight = contentHeight
+
+    if #available(iOS 15.0, *) {
+      withPresentedSheet { _ in
+        viewController.setupSizes()
+      }
+    }
   }
 
   @objc
@@ -257,13 +272,22 @@ class TrueSheetView: UIView, RCTInvalidating, TrueSheetViewControllerDelegate {
       footerViewHeightConstraint.constant = 0
     }
 
-    configurePresentedSheet()
+    if #available(iOS 15.0, *) {
+      withPresentedSheet { _ in
+        viewController.setupSizes()
+      }
+    }
   }
 
   @objc
   func setSizes(_ sizes: [Any]) {
     viewController.sizes = Array(sizes.prefix(3))
-    configurePresentedSheet()
+
+    if #available(iOS 15.0, *) {
+      withPresentedSheet { _ in
+        viewController.setupSizes()
+      }
+    }
   }
 
   @objc
@@ -319,8 +343,8 @@ class TrueSheetView: UIView, RCTInvalidating, TrueSheetViewControllerDelegate {
     viewController.dimmed = dimmed
 
     if #available(iOS 15.0, *) {
-      withPresentedSheet { sheet in
-        viewController.setupDimmedBackground(for: sheet)
+      withPresentedSheet { _ in
+        viewController.setupDimmedBackground()
       }
     }
   }
@@ -334,8 +358,8 @@ class TrueSheetView: UIView, RCTInvalidating, TrueSheetViewControllerDelegate {
     viewController.dimmedIndex = index.intValue
 
     if #available(iOS 15.0, *) {
-      withPresentedSheet { sheet in
-        viewController.setupDimmedBackground(for: sheet)
+      withPresentedSheet { _ in
+        viewController.setupDimmedBackground()
       }
     }
   }
@@ -367,13 +391,6 @@ class TrueSheetView: UIView, RCTInvalidating, TrueSheetViewControllerDelegate {
     }
   }
 
-  /// Fully reconfigure the sheet. Use during size prop changes.
-  func configurePresentedSheet() {
-    if isPresented {
-      viewController.configureSheet(at: activeIndex ?? 0, nil)
-    }
-  }
-
   func setupScrollable() {
     guard let contentView, let containerView, let scrollableTag else {
       return
@@ -416,12 +433,16 @@ class TrueSheetView: UIView, RCTInvalidating, TrueSheetViewControllerDelegate {
       return
     }
 
-    viewController.configureSheet(at: index) {
-      // Trigger onSizeChange event when size is changed while presenting
-      if self.isPresented {
-        self.viewControllerDidChangeSize(self.viewController.currentSizeInfo)
+    if isPresented {
+      withPresentedSheet { sheet in
+        sheet.selectedDetentIdentifier = viewController.detentIdentifierForIndex(index)
+
+        // Trigger onSizeChange event when size is changed while presenting
+        viewControllerDidChangeSize(self.viewController.currentSizeInfo)
         promise?.resolve(nil)
-      } else {
+      }
+    } else {
+      viewController.prepareForPresentation(at: index) {
         // Keep track of the active index
         self.activeIndex = index
         self.isPresented = true

ios/TrueSheetViewController.swift

@@ -160,17 +160,6 @@ class TrueSheetViewController: UIViewController, UISheetPresentationControllerDe
     }
   }
 
-  func setContentHeight(_ height: CGFloat) {
-    // Exclude bottom safe area for consistency with a Scrollable content
-    let adjustedContentHeight = height - bottomInset
-
-    guard contentHeight != adjustedContentHeight else {
-      return
-    }
-
-    contentHeight = adjustedContentHeight
-  }
-
   /// Setup background. Supports color or blur effect.
   /// Can only use one or the other.
   func setupBackground() {
@@ -186,7 +175,11 @@ class TrueSheetViewController: UIViewController, UISheetPresentationControllerDe
   /// Setup dimmed sheet.
   /// `dimmedIndex` will further customize the dimming behavior.
   @available(iOS 15.0, *)
-  func setupDimmedBackground(for sheet: UISheetPresentationController) {
+  func setupDimmedBackground() {
+    guard let sheet = sheetPresentationController else {
+      return
+    }
+
     if dimmed, dimmedIndex == 0 {
       sheet.largestUndimmedDetentIdentifier = nil
     } else {
@@ -202,6 +195,50 @@ class TrueSheetViewController: UIViewController, UISheetPresentationControllerDe
     }
   }
 
+  /// Setup sheet detents by sizes.
+  @available(iOS 15.0, *)
+  func setupSizes() {
+    guard let sheet = sheetPresentationController else {
+      return
+    }
+
+    // Configure detents
+    detentValues = [:]
+    var detents: [UISheetPresentationController.Detent] = []
+
+    for (index, size) in sizes.enumerated() {
+      // Exclude bottom safe area for consistency with a Scrollable content
+      let adjustedContentHeight = contentHeight - bottomInset
+      let detent = detentFor(size, with: adjustedContentHeight + footerHeight, with: maxHeight) { id, value in
+        self.detentValues[id] = SizeInfo(index: index, value: value)
+      }
+
+      detents.append(detent)
+    }
+
+    sheet.detents = detents
+  }
+
+  /// Get the detent identifier for a given index
+  @available(iOS 15.0, *)
+  func detentIdentifierForIndex(_ index: Int) -> UISheetPresentationController.Detent.Identifier {
+    guard let sheet = sheetPresentationController else {
+      return .medium
+    }
+
+    var identifier = UISheetPresentationController.Detent.Identifier.medium
+    if sheet.detents.indices.contains(index) {
+      let detent = sheet.detents[index]
+      if #available(iOS 16.0, *) {
+        identifier = detent.identifier
+      } else if detent == .large() {
+        identifier = .large
+      }
+    }
+
+    return identifier
+  }
+
   /// Observe while the sheet is being dragged.
   @available(iOS 15.0, *)
   func observeDrag() {
@@ -218,46 +255,21 @@ class TrueSheetViewController: UIViewController, UISheetPresentationControllerDe
   }
 
   /// Prepares the view controller for sheet presentation
-  func configureSheet(at index: Int = 0, _ completion: (() -> Void)?) {
+  func prepareForPresentation(at index: Int = 0, _ completion: (() -> Void)?) {
     guard #available(iOS 15.0, *), let sheet = sheetPresentationController else {
       completion?()
       return
     }
 
-    detentValues = [:]
-
-    var detents: [UISheetPresentationController.Detent] = []
-
-    for (index, size) in sizes.enumerated() {
-      let detent = detentFor(size, with: contentHeight + footerHeight, with: maxHeight) { id, value in
-        self.detentValues[id] = SizeInfo(index: index, value: value)
-      }
-
-      detents.append(detent)
-    }
-
-    sheet.animateChanges {
-      sheet.detents = detents
-      sheet.prefersEdgeAttachedInCompactHeight = true
-      sheet.prefersGrabberVisible = grabber
-      sheet.preferredCornerRadius = cornerRadius
-      sheet.delegate = self
-
-      var identifier: UISheetPresentationController.Detent.Identifier = .medium
-
-      if sheet.detents.indices.contains(index) {
-        let detent = sheet.detents[index]
-        if #available(iOS 16.0, *) {
-          identifier = detent.identifier
-        } else if detent == .large() {
-          identifier = .large
-        }
-      }
+    setupSizes()
+    setupDimmedBackground()
 
-      setupDimmedBackground(for: sheet)
+    sheet.delegate = self
+    sheet.prefersEdgeAttachedInCompactHeight = true
+    sheet.prefersGrabberVisible = grabber
+    sheet.preferredCornerRadius = cornerRadius
+    sheet.selectedDetentIdentifier = detentIdentifierForIndex(index)
 
-      sheet.selectedDetentIdentifier = identifier
-      completion?()
-    }
+    completion?()
   }
 }