Avoid timeout when the app starts up in the background

Closes #9.

src/ios/WebAppLocalServer.swift

@@ -112,10 +112,12 @@ open class WebAppLocalServer: METPlugin, AssetBundleManagerDelegate {
         self?.revertToLastKnownGoodVersion()
       }
     }
+
+    NotificationCenter.default.addObserver(self, selector: #selector(WebAppLocalServer.pageDidLoad), name: NSNotification.Name.CDVPageDidLoad, object: webView)
 
     NotificationCenter.default.addObserver(self, selector: #selector(WebAppLocalServer.applicationDidEnterBackground), name: NSNotification.Name.UIApplicationDidEnterBackground, object: nil)
-
-    NotificationCenter.default.addObserver(self, selector: #selector(WebAppLocalServer.pageDidLoad), name: NSNotification.Name.CDVPageDidLoad, object: webView)
+    
+    NotificationCenter.default.addObserver(self, selector: #selector(WebAppLocalServer.applicationWillEnterForeground), name: NSNotification.Name.UIApplicationWillEnterForeground, object: nil)
   }
 
   func initializeAssetBundles() {
@@ -194,7 +196,10 @@ open class WebAppLocalServer: METPlugin, AssetBundleManagerDelegate {
       self.pendingAssetBundle = nil
     }
 
-    startupTimer?.start(withTimeInterval: startupTimeoutInterval)
+    // Don't start the startup timer if the app started up in the background
+    if UIApplication.shared.applicationState == UIApplicationState.active {
+      startupTimer?.start(withTimeInterval: startupTimeoutInterval)
+    }
   }
 
   // MARK: - Notifications
@@ -207,6 +212,11 @@ open class WebAppLocalServer: METPlugin, AssetBundleManagerDelegate {
     // blacklisting a version just because the web view has been suspended
     startupTimer?.stop()
   }
+
+  func applicationWillEnterForeground() {
+    // Restart startup timer when entering the foreground again
+    startupTimer?.start(withTimeInterval: startupTimeoutInterval)
+  }
 
   // MARK: - Public plugin commands