From 286a6f1c4eb1531187ab54c4100f900037533c8f Mon Sep 17 00:00:00 2001
From: Maurice Parrish <10687576+bparrishMines@users.noreply.github.com>
Date: Tue, 14 Jun 2022 09:39:23 -0700
Subject: [PATCH 1/2] fix error call to remove observer

---
 .../lib/src/web_kit_webview_widget.dart       | 28 ++++++++++++++++---
 .../test/src/web_kit_webview_widget_test.dart | 10 +++++++
 2 files changed, 34 insertions(+), 4 deletions(-)

diff --git a/packages/webview_flutter/webview_flutter_wkwebview/lib/src/web_kit_webview_widget.dart b/packages/webview_flutter/webview_flutter_wkwebview/lib/src/web_kit_webview_widget.dart
index 05a77f56f851..ce48e9d27e16 100644
--- a/packages/webview_flutter/webview_flutter_wkwebview/lib/src/web_kit_webview_widget.dart
+++ b/packages/webview_flutter/webview_flutter_wkwebview/lib/src/web_kit_webview_widget.dart
@@ -69,6 +69,12 @@ class _WebKitWebViewWidgetState extends State<WebKitWebViewWidget> {
     );
   }
 
+  @override
+  void dispose() {
+    super.dispose();
+    controller._dispose();
+  }
+
   @override
   Widget build(BuildContext context) {
     return widget.onBuildWidget(controller);
@@ -93,6 +99,7 @@ class WebKitWebViewPlatformController extends WebViewPlatformController {
 
   bool _zoomEnabled = true;
   bool _hasNavigationDelegate = false;
+  bool _progressObserverSet = false;
 
   final Map<String, WKScriptMessageHandler> _scriptMessageHandlers =
       <String, WKScriptMessageHandler>{};
@@ -452,17 +459,20 @@ class WebKitWebViewPlatformController extends WebViewPlatformController {
     await _resetUserScripts(removedJavaScriptChannels: javascriptChannelNames);
   }
 
-  Future<void> _setHasProgressTracking(bool hasProgressTracking) {
+  Future<void> _setHasProgressTracking(bool hasProgressTracking) async {
     if (hasProgressTracking) {
-      return webView.addObserver(
+      _progressObserverSet = true;
+      await webView.addObserver(
         webView,
         keyPath: 'estimatedProgress',
         options: <NSKeyValueObservingOptions>{
           NSKeyValueObservingOptions.newValue,
         },
       );
-    } else {
-      return webView.removeObserver(webView, keyPath: 'estimatedProgress');
+    } else if (_progressObserverSet) {
+      // Calls to removeObserver before addObserver causes a crash.
+      _progressObserverSet = false;
+      await webView.removeObserver(webView, keyPath: 'estimatedProgress');
     }
   }
 
@@ -593,6 +603,16 @@ class WebKitWebViewPlatformController extends WebViewPlatformController {
 
     return value.toString();
   }
+
+  void _dispose() {
+    if (_progressObserverSet) {
+      _progressObserverSet = false;
+      // It is recommended by Apple's documentation that this should be called
+      // before the WebView is deallocated:
+      // https://developer.apple.com/documentation/objectivec/nsobject/1408054-removeobserver?language=objc
+      webView.removeObserver(webView, keyPath: 'estimatedProgress');
+    }
+  }
 }
 
 /// Handles constructing objects and calling static methods.
diff --git a/packages/webview_flutter/webview_flutter_wkwebview/test/src/web_kit_webview_widget_test.dart b/packages/webview_flutter/webview_flutter_wkwebview/test/src/web_kit_webview_widget_test.dart
index 24155d2a05e1..14b68fcb4500 100644
--- a/packages/webview_flutter/webview_flutter_wkwebview/test/src/web_kit_webview_widget_test.dart
+++ b/packages/webview_flutter/webview_flutter_wkwebview/test/src/web_kit_webview_widget_test.dart
@@ -1151,6 +1151,16 @@ void main() {
 
         verify(mockCallbacksHandler.onProgress(32));
       });
+
+      testWidgets('progress observer is not removed without being set first',
+          (WidgetTester tester) async {
+        await buildWidget(tester, hasProgressTracking: false);
+
+        verifyNever(mockWebView.removeObserver(
+          mockWebView,
+          keyPath: 'estimatedProgress',
+        ));
+      });
     });
 
     group('JavascriptChannelRegistry', () {

From 57d7cb666984ab65e3e69bc4e401500facc08d62 Mon Sep 17 00:00:00 2001
From: Maurice Parrish <10687576+bparrishMines@users.noreply.github.com>
Date: Tue, 14 Jun 2022 19:59:53 -0700
Subject: [PATCH 2/2] remove _dispose

---
 .../lib/src/web_kit_webview_widget.dart          | 16 ----------------
 1 file changed, 16 deletions(-)

diff --git a/packages/webview_flutter/webview_flutter_wkwebview/lib/src/web_kit_webview_widget.dart b/packages/webview_flutter/webview_flutter_wkwebview/lib/src/web_kit_webview_widget.dart
index ce48e9d27e16..7bb020e1a760 100644
--- a/packages/webview_flutter/webview_flutter_wkwebview/lib/src/web_kit_webview_widget.dart
+++ b/packages/webview_flutter/webview_flutter_wkwebview/lib/src/web_kit_webview_widget.dart
@@ -69,12 +69,6 @@ class _WebKitWebViewWidgetState extends State<WebKitWebViewWidget> {
     );
   }
 
-  @override
-  void dispose() {
-    super.dispose();
-    controller._dispose();
-  }
-
   @override
   Widget build(BuildContext context) {
     return widget.onBuildWidget(controller);
@@ -603,16 +597,6 @@ class WebKitWebViewPlatformController extends WebViewPlatformController {
 
     return value.toString();
   }
-
-  void _dispose() {
-    if (_progressObserverSet) {
-      _progressObserverSet = false;
-      // It is recommended by Apple's documentation that this should be called
-      // before the WebView is deallocated:
-      // https://developer.apple.com/documentation/objectivec/nsobject/1408054-removeobserver?language=objc
-      webView.removeObserver(webView, keyPath: 'estimatedProgress');
-    }
-  }
 }
 
 /// Handles constructing objects and calling static methods.