packages/webview_flutter/webview_flutter_wkwebview/lib/src/web_kit_webview_widget.dart - mirrors/plugins - Git at Google

 // Copyright 2013 The Flutter Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.

 import 'dart:async';
 import 'dart:math';

 import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter/services.dart';
 import 'package:path/path.dart' as path;
 import 'package:webview_flutter_platform_interface/webview_flutter_platform_interface.dart';

 import 'foundation/foundation.dart';
 import 'web_kit/web_kit.dart';

 /// A [Widget] that displays a [WKWebView].
 class WebKitWebViewWidget extends StatefulWidget {
   /// Constructs a [WebKitWebViewWidget].
   const WebKitWebViewWidget({
     Key? key,
     required this.creationParams,
     required this.callbacksHandler,
     required this.javascriptChannelRegistry,
     required this.onBuildWidget,
     this.configuration,
     @visibleForTesting this.webViewProxy = const WebViewWidgetProxy(),
   }) : super(key: key);

   /// The initial parameters used to setup the WebView.
   final CreationParams creationParams;

   /// The handler of callbacks made made by [NavigationDelegate].
   final WebViewPlatformCallbacksHandler callbacksHandler;

   /// Manager of named JavaScript channels and forwarding incoming messages on the correct channel.
   final JavascriptChannelRegistry javascriptChannelRegistry;

   /// A collection of properties used to initialize a web view.
   ///
   /// If null, a default configuration is used.
   final WKWebViewConfiguration? configuration;

   /// The handler for constructing [WKWebView]s and calling static methods.
   ///
   /// This should only be changed for testing purposes.
   final WebViewWidgetProxy webViewProxy;

   /// A callback to build a widget once [WKWebView] has been initialized.
   final Widget Function(WebKitWebViewPlatformController controller)
       onBuildWidget;

   @override
   State<StatefulWidget> createState() => _WebKitWebViewWidgetState();
 }

 class _WebKitWebViewWidgetState extends State<WebKitWebViewWidget> {
   late final WebKitWebViewPlatformController controller;

   @override
   void initState() {
     super.initState();
     controller = WebKitWebViewPlatformController(
       creationParams: widget.creationParams,
       callbacksHandler: widget.callbacksHandler,
       javascriptChannelRegistry: widget.javascriptChannelRegistry,
       configuration: widget.configuration,
       webViewProxy: widget.webViewProxy,
     );
   }

   @override
   Widget build(BuildContext context) {
     return widget.onBuildWidget(controller);
   }
 }

 /// An implementation of [WebViewPlatformController] with the WebKit api.
 class WebKitWebViewPlatformController extends WebViewPlatformController {
   /// Construct a [WebKitWebViewPlatformController].
   WebKitWebViewPlatformController({
     required CreationParams creationParams,
     required this.callbacksHandler,
     required this.javascriptChannelRegistry,
     WKWebViewConfiguration? configuration,
     @visibleForTesting this.webViewProxy = const WebViewWidgetProxy(),
   }) : super(callbacksHandler) {
     _setCreationParams(
       creationParams,
       configuration: configuration ?? WKWebViewConfiguration(),
     );
   }

   bool _zoomEnabled = true;

   final Map<String, WKScriptMessageHandler> _scriptMessageHandlers =
       <String, WKScriptMessageHandler>{};

   /// Handles callbacks that are made by navigation.
   final WebViewPlatformCallbacksHandler callbacksHandler;

   /// Manages named JavaScript channels and forwarding incoming messages on the correct channel.
   final JavascriptChannelRegistry javascriptChannelRegistry;

   /// Handles constructing a [WKWebView].
   ///
   /// This should only be changed when used for testing.
   final WebViewWidgetProxy webViewProxy;

   /// Represents the WebView maintained by platform code.
   late final WKWebView webView;

   /// Used to integrate custom user interface elements into web view interactions.
   @visibleForTesting
   late final WKUIDelegate uiDelegate = webViewProxy.createUIDelgate();

   /// Methods for handling navigation changes and tracking navigation requests.
   @visibleForTesting
   late final WKNavigationDelegate navigationDelegate =
       webViewProxy.createNavigationDelegate()
         ..setDidStartProvisionalNavigation((WKWebView webView, String? url) {
           callbacksHandler.onPageStarted(url ?? '');
         })
         ..setDidFinishNavigation((WKWebView webView, String? url) {
           callbacksHandler.onPageFinished(url ?? '');
         })
         ..setDidFailNavigation((WKWebView webView, NSError error) {
           callbacksHandler.onWebResourceError(_toWebResourceError(error));
         })
         ..setDidFailProvisionalNavigation((WKWebView webView, NSError error) {
           callbacksHandler.onWebResourceError(_toWebResourceError(error));
         })
         ..setWebViewWebContentProcessDidTerminate((WKWebView webView) {
           callbacksHandler.onWebResourceError(WebResourceError(
             errorCode: WKErrorCode.webContentProcessTerminated,
             // Value from https://developer.apple.com/documentation/webkit/wkerrordomain?language=objc.
             domain: 'WKErrorDomain',
             description: '',
             errorType: WebResourceErrorType.webContentProcessTerminated,
           ));
         });

   Future<void> _setCreationParams(
     CreationParams params, {
     required WKWebViewConfiguration configuration,
   }) async {
     _setWebViewConfiguration(
       configuration,
       allowsInlineMediaPlayback: params.webSettings?.allowsInlineMediaPlayback,
       autoMediaPlaybackPolicy: params.autoMediaPlaybackPolicy,
     );

     webView = webViewProxy.createWebView(configuration);

     webView.setUIDelegate(uiDelegate);
     uiDelegate.setOnCreateWebView((
       WKWebViewConfiguration configuration,
       WKNavigationAction navigationAction,
     ) {
       if (!navigationAction.targetFrame.isMainFrame) {
         webView.loadRequest(navigationAction.request);
       }
     });

     await addJavascriptChannels(params.javascriptChannelNames);

     webView.setNavigationDelegate(navigationDelegate);

     if (params.userAgent != null) {
       webView.setCustomUserAgent(params.userAgent);
     }

     if (params.webSettings != null) {
       updateSettings(params.webSettings!);
     }

     if (params.backgroundColor != null) {
       webView.setOpaque(false);
       webView.setBackgroundColor(Colors.transparent);
       webView.scrollView.setBackgroundColor(params.backgroundColor);
     }

     if (params.initialUrl != null) {
       await loadUrl(params.initialUrl!, null);
     }
   }

   void _setWebViewConfiguration(
     WKWebViewConfiguration configuration, {
     required bool? allowsInlineMediaPlayback,
     required AutoMediaPlaybackPolicy autoMediaPlaybackPolicy,
   }) {
     if (allowsInlineMediaPlayback != null) {
       configuration.setAllowsInlineMediaPlayback(allowsInlineMediaPlayback);
     }

     late final bool requiresUserAction;
     switch (autoMediaPlaybackPolicy) {
       case AutoMediaPlaybackPolicy.require_user_action_for_all_media_types:
         requiresUserAction = true;
         break;
       case AutoMediaPlaybackPolicy.always_allow:
         requiresUserAction = false;
         break;
     }

     configuration
         .setMediaTypesRequiringUserActionForPlayback(<WKAudiovisualMediaType>{
       if (requiresUserAction) WKAudiovisualMediaType.all,
       if (!requiresUserAction) WKAudiovisualMediaType.none,
     });
   }

   @override
   Future<void> loadHtmlString(String html, {String? baseUrl}) {
     return webView.loadHtmlString(html, baseUrl: baseUrl);
   }

   @override
   Future<void> loadFile(String absoluteFilePath) async {
     await webView.loadFileUrl(
       absoluteFilePath,
       readAccessUrl: path.dirname(absoluteFilePath),
     );
   }

   @override
   Future<void> clearCache() {
     return webView.configuration.websiteDataStore.removeDataOfTypes(
       <WKWebsiteDataType>{
         WKWebsiteDataType.memoryCache,
         WKWebsiteDataType.diskCache,
         WKWebsiteDataType.offlineWebApplicationCache,
         WKWebsiteDataType.localStorage,
       },
       DateTime.fromMillisecondsSinceEpoch(0),
     );
   }

   @override
   Future<void> loadFlutterAsset(String key) async {
     assert(key.isNotEmpty);
     return webView.loadFlutterAsset(key);
   }

   @override
   Future<void> loadUrl(String url, Map<String, String>? headers) async {
     final NSUrlRequest request = NSUrlRequest(
       url: url,
       allHttpHeaderFields: headers ?? <String, String>{},
     );
     return webView.loadRequest(request);
   }

   @override
   Future<void> loadRequest(WebViewRequest request) async {
     if (!request.uri.hasScheme) {
       throw ArgumentError('WebViewRequest#uri is required to have a scheme.');
     }

     final NSUrlRequest urlRequest = NSUrlRequest(
       url: request.uri.toString(),
       allHttpHeaderFields: request.headers,
       httpMethod: describeEnum(request.method),
       httpBody: request.body,
     );

     return webView.loadRequest(urlRequest);
   }

   @override
   Future<bool> canGoBack() => webView.canGoBack();

   @override
   Future<bool> canGoForward() => webView.canGoForward();

   @override
   Future<void> goBack() => webView.goBack();

   @override
   Future<void> goForward() => webView.goForward();

   @override
   Future<void> reload() => webView.reload();

   @override
   Future<String> evaluateJavascript(String javascript) async {
     final Object? result = await webView.evaluateJavaScript(javascript);
     // The legacy implementation of webview_flutter_wkwebview would convert
     // objects to strings before returning them to Dart. This method attempts
     // to converts Dart objects to Strings the way it is done in Objective-C
     // to avoid breaking users expecting the same String format.
     return _asObjectiveCString(result);
   }

   @override
   Future<void> runJavascript(String javascript) async {
     try {
       await webView.evaluateJavaScript(javascript);
     } on PlatformException catch (exception) {
       // WebKit will throw an error when the type of the evaluated value is
       // unsupported. This also goes for `null` and `undefined` on iOS 14+. For
       // example, when running a void function. For ease of use, this specific
       // error is ignored when no return value is expected.
       // TODO(bparrishMines): Ensure the platform code includes the NSError in
       // the FlutterError.details.
       if (exception.details is! NSError ||
           exception.details.code !=
               WKErrorCode.javaScriptResultTypeIsUnsupported) {
         rethrow;
       }
     }
   }

   @override
   Future<String> runJavascriptReturningResult(String javascript) async {
     final Object? result = await webView.evaluateJavaScript(javascript);
     if (result == null) {
       throw ArgumentError(
         'Result of JavaScript execution returned a `null` value. '
         'Use `runJavascript` when expecting a null return value.',
       );
     }
     return result.toString();
   }

   @override
   Future<String?> getTitle() => webView.getTitle();

   @override
   Future<void> scrollTo(int x, int y) async {
     webView.scrollView.setContentOffset(Point<double>(
       x.toDouble(),
       y.toDouble(),
     ));
   }

   @override
   Future<void> scrollBy(int x, int y) async {
     await webView.scrollView.scrollBy(Point<double>(
       x.toDouble(),
       y.toDouble(),
     ));
   }

   @override
   Future<int> getScrollX() async {
     final Point<double> offset = await webView.scrollView.getContentOffset();
     return offset.x.toInt();
   }

   @override
   Future<int> getScrollY() async {
     final Point<double> offset = await webView.scrollView.getContentOffset();
     return offset.y.toInt();
   }

   @override
   Future<void> updateSettings(WebSettings setting) async {
     await Future.wait(<Future<void>>[
       _setUserAgent(setting.userAgent),
       if (setting.hasNavigationDelegate != null)
         _setHasNavigationDelegate(setting.hasNavigationDelegate!),
       if (setting.hasProgressTracking != null)
         _setHasProgressTracking(setting.hasProgressTracking!),
       if (setting.javascriptMode != null)
         _setJavaScriptMode(setting.javascriptMode!),
       if (setting.zoomEnabled != null) _setZoomEnabled(setting.zoomEnabled!),
       if (setting.gestureNavigationEnabled != null)
         webView.setAllowsBackForwardNavigationGestures(
           setting.gestureNavigationEnabled!,
         ),
     ]);
   }

   @override
   Future<void> addJavascriptChannels(Set<String> javascriptChannelNames) async {
     await Future.wait<void>(
       javascriptChannelNames.where(
         (String channelName) {
           return !_scriptMessageHandlers.containsKey(channelName);
         },
       ).map<Future<void>>(
         (String channelName) {
           final WKScriptMessageHandler handler =
               webViewProxy.createScriptMessageHandler()
                 ..setDidReceiveScriptMessage((
                   WKUserContentController userContentController,
                   WKScriptMessage message,
                 ) {
                   javascriptChannelRegistry.onJavascriptChannelMessage(
                     message.name,
                     message.body!.toString(),
                   );
                 });
           _scriptMessageHandlers[channelName] = handler;

           final String wrapperSource =
               'window.$channelName = webkit.messageHandlers.$channelName;';
           final WKUserScript wrapperScript = WKUserScript(
             wrapperSource,
             WKUserScriptInjectionTime.atDocumentStart,
             isMainFrameOnly: false,
           );
           webView.configuration.userContentController
               .addUserScript(wrapperScript);
           return webView.configuration.userContentController
               .addScriptMessageHandler(
             handler,
             channelName,
           );
         },
       ),
     );
   }

   @override
   Future<void> removeJavascriptChannels(
     Set<String> javascriptChannelNames,
   ) async {
     if (javascriptChannelNames.isEmpty) {
       return;
     }

     await _resetUserScripts(removedJavaScriptChannels: javascriptChannelNames);
   }

   Future<void> _setHasNavigationDelegate(bool hasNavigationDelegate) {
     if (hasNavigationDelegate) {
       return navigationDelegate.setDecidePolicyForNavigationAction(
           (WKWebView webView, WKNavigationAction action) async {
         final bool allow = await callbacksHandler.onNavigationRequest(
           url: action.request.url,
           isForMainFrame: action.targetFrame.isMainFrame,
         );

         return allow
             ? WKNavigationActionPolicy.allow
             : WKNavigationActionPolicy.cancel;
       });
     } else {
       return navigationDelegate.setDecidePolicyForNavigationAction(null);
     }
   }

   Future<void> _setHasProgressTracking(bool hasProgressTracking) {
     if (hasProgressTracking) {
       webView.setObserveValue((
         String keyPath,
         NSObject object,
         Map<NSKeyValueChangeKey, Object?> change,
       ) {
         final double progress = change[NSKeyValueChangeKey.newValue]! as double;
         callbacksHandler.onProgress((progress * 100).round());
       });
       return webView.addObserver(
         webView,
         keyPath: 'estimatedProgress',
         options: <NSKeyValueObservingOptions>{
           NSKeyValueObservingOptions.newValue,
         },
       );
     } else {
       webView.setObserveValue(null);
       return webView.removeObserver(webView, keyPath: 'estimatedProgress');
     }
   }

   Future<void> _setJavaScriptMode(JavascriptMode mode) {
     switch (mode) {
       case JavascriptMode.disabled:
         return webView.configuration.preferences.setJavaScriptEnabled(false);
       case JavascriptMode.unrestricted:
         return webView.configuration.preferences.setJavaScriptEnabled(true);
     }
   }

   Future<void> _setUserAgent(WebSetting<String?> userAgent) async {
     if (userAgent.isPresent) {
       await webView.setCustomUserAgent(userAgent.value);
     }
   }

   Future<void> _setZoomEnabled(bool zoomEnabled) async {
     if (_zoomEnabled == zoomEnabled) {
       return;
     }

     _zoomEnabled = zoomEnabled;
     if (!zoomEnabled) {
       return _disableZoom();
     }

     return _resetUserScripts();
   }

   Future<void> _disableZoom() {
     const WKUserScript userScript = WKUserScript(
       "var meta = document.createElement('meta');\n"
       "meta.name = 'viewport';\n"
       "meta.content = 'width=device-width, initial-scale=1.0, maximum-scale=1.0, "
       "user-scalable=no';\n"
       "var head = document.getElementsByTagName('head')[0];head.appendChild(meta);",
       WKUserScriptInjectionTime.atDocumentEnd,
       isMainFrameOnly: true,
     );
     return webView.configuration.userContentController
         .addUserScript(userScript);
   }

   // WkWebView does not support removing a single user script, so all user
   // scripts and all message handlers are removed instead. And the JavaScript
   // channels that shouldn't be removed are re-registered. Note that this
   // workaround could interfere with exposing support for custom scripts from
   // applications.
   Future<void> _resetUserScripts({
     Set<String> removedJavaScriptChannels = const <String>{},
   }) async {
     webView.configuration.userContentController.removeAllUserScripts();
     // TODO(bparrishMines): This can be replaced with
     // `removeAllScriptMessageHandlers` once Dart supports runtime version
     // checking. (e.g. The equivalent to @availability in Objective-C.)
     _scriptMessageHandlers.keys.forEach(
       webView.configuration.userContentController.removeScriptMessageHandler,
     );

     removedJavaScriptChannels.forEach(_scriptMessageHandlers.remove);
     final Set<String> remainingNames = _scriptMessageHandlers.keys.toSet();
     _scriptMessageHandlers.clear();

     await Future.wait(<Future<void>>[
       addJavascriptChannels(remainingNames),
       // Zoom is disabled with a WKUserScript, so this adds it back if it was
       // removed above.
       if (!_zoomEnabled) _disableZoom(),
     ]);
   }

   static WebResourceError _toWebResourceError(NSError error) {
     WebResourceErrorType? errorType;

     switch (error.code) {
       case WKErrorCode.unknown:
         errorType = WebResourceErrorType.unknown;
         break;
       case WKErrorCode.webContentProcessTerminated:
         errorType = WebResourceErrorType.webContentProcessTerminated;
         break;
       case WKErrorCode.webViewInvalidated:
         errorType = WebResourceErrorType.webViewInvalidated;
         break;
       case WKErrorCode.javaScriptExceptionOccurred:
         errorType = WebResourceErrorType.javaScriptExceptionOccurred;
         break;
       case WKErrorCode.javaScriptResultTypeIsUnsupported:
         errorType = WebResourceErrorType.javaScriptResultTypeIsUnsupported;
         break;
     }

     return WebResourceError(
       errorCode: error.code,
       domain: error.domain,
       description: error.localizedDescription,
       errorType: errorType,
     );
   }

   String _asObjectiveCString(Object? value, {bool inContainer = false}) {
     if (value == null) {
       // An NSNull inside an NSArray or NSDictionary is represented as a String
       // differently than a nil.
       if (inContainer) {
         return '"<null>"';
       }
       return '(null)';
     } else if (value is List) {
       final List<String> stringValues = <String>[];
       for (final Object? listValue in value) {
         stringValues.add(_asObjectiveCString(listValue, inContainer: true));
       }
       return '(${stringValues.join(',')})';
     } else if (value is Map) {
       final List<String> stringValues = <String>[];
       for (final MapEntry<Object?, Object?> entry in value.entries) {
         stringValues.add(
           '${_asObjectiveCString(entry.key, inContainer: true)} '
           '= '
           '${_asObjectiveCString(entry.value, inContainer: true)}',
         );
       }
       return '{${stringValues.join(';')}}';
     }

     return value.toString();
   }
 }

 /// Handles constructing objects and calling static methods.
 ///
 /// This should only be used for testing purposes.
 @visibleForTesting
 class WebViewWidgetProxy {
   /// Constructs a [WebViewWidgetProxy].
   const WebViewWidgetProxy();

   /// Constructs a [WKWebView].
   WKWebView createWebView(WKWebViewConfiguration configuration) {
     return WKWebView(configuration);
   }

   /// Constructs a [WKScriptMessageHandler].
   WKScriptMessageHandler createScriptMessageHandler() {
     return WKScriptMessageHandler();
   }

   /// Constructs a [WKUIDelegate].
   WKUIDelegate createUIDelgate() {
     return WKUIDelegate();
   }

   /// Constructs a [WKNavigationDelegate].
   WKNavigationDelegate createNavigationDelegate() {
     return WKNavigationDelegate();
   }
 }
	// Copyright 2013 The Flutter Authors. All rights reserved.
	// Use of this source code is governed by a BSD-style license that can be
	// found in the LICENSE file.

	import 'dart:async';
	import 'dart:math';

	import 'package:flutter/foundation.dart';
	import 'package:flutter/material.dart';
	import 'package:flutter/services.dart';
	import 'package:path/path.dart' as path;
	import 'package:webview_flutter_platform_interface/webview_flutter_platform_interface.dart';

	import 'foundation/foundation.dart';
	import 'web_kit/web_kit.dart';

	/// A [Widget] that displays a [WKWebView].
	class WebKitWebViewWidget extends StatefulWidget {
	/// Constructs a [WebKitWebViewWidget].
	const WebKitWebViewWidget({
	Key? key,
	required this.creationParams,
	required this.callbacksHandler,
	required this.javascriptChannelRegistry,
	required this.onBuildWidget,
	this.configuration,
	@visibleForTesting this.webViewProxy = const WebViewWidgetProxy(),
	}) : super(key: key);

	/// The initial parameters used to setup the WebView.
	final CreationParams creationParams;

	/// The handler of callbacks made made by [NavigationDelegate].
	final WebViewPlatformCallbacksHandler callbacksHandler;

	/// Manager of named JavaScript channels and forwarding incoming messages on the correct channel.
	final JavascriptChannelRegistry javascriptChannelRegistry;

	/// A collection of properties used to initialize a web view.
	///
	/// If null, a default configuration is used.
	final WKWebViewConfiguration? configuration;

	/// The handler for constructing [WKWebView]s and calling static methods.
	///
	/// This should only be changed for testing purposes.
	final WebViewWidgetProxy webViewProxy;

	/// A callback to build a widget once [WKWebView] has been initialized.
	final Widget Function(WebKitWebViewPlatformController controller)
	onBuildWidget;

	@override
	State<StatefulWidget> createState() => _WebKitWebViewWidgetState();
	}

	class _WebKitWebViewWidgetState extends State<WebKitWebViewWidget> {
	late final WebKitWebViewPlatformController controller;

	@override
	void initState() {
	super.initState();
	controller = WebKitWebViewPlatformController(
	creationParams: widget.creationParams,
	callbacksHandler: widget.callbacksHandler,
	javascriptChannelRegistry: widget.javascriptChannelRegistry,
	configuration: widget.configuration,
	webViewProxy: widget.webViewProxy,
	);
	}

	@override
	Widget build(BuildContext context) {
	return widget.onBuildWidget(controller);
	}
	}

	/// An implementation of [WebViewPlatformController] with the WebKit api.
	class WebKitWebViewPlatformController extends WebViewPlatformController {
	/// Construct a [WebKitWebViewPlatformController].
	WebKitWebViewPlatformController({
	required CreationParams creationParams,
	required this.callbacksHandler,
	required this.javascriptChannelRegistry,
	WKWebViewConfiguration? configuration,
	@visibleForTesting this.webViewProxy = const WebViewWidgetProxy(),
	}) : super(callbacksHandler) {
	_setCreationParams(
	creationParams,
	configuration: configuration ?? WKWebViewConfiguration(),
	);
	}

	bool _zoomEnabled = true;

	final Map<String, WKScriptMessageHandler> _scriptMessageHandlers =
	<String, WKScriptMessageHandler>{};

	/// Handles callbacks that are made by navigation.
	final WebViewPlatformCallbacksHandler callbacksHandler;

	/// Manages named JavaScript channels and forwarding incoming messages on the correct channel.
	final JavascriptChannelRegistry javascriptChannelRegistry;

	/// Handles constructing a [WKWebView].
	///
	/// This should only be changed when used for testing.
	final WebViewWidgetProxy webViewProxy;

	/// Represents the WebView maintained by platform code.
	late final WKWebView webView;

	/// Used to integrate custom user interface elements into web view interactions.
	@visibleForTesting
	late final WKUIDelegate uiDelegate = webViewProxy.createUIDelgate();

	/// Methods for handling navigation changes and tracking navigation requests.
	@visibleForTesting
	late final WKNavigationDelegate navigationDelegate =
	webViewProxy.createNavigationDelegate()
	..setDidStartProvisionalNavigation((WKWebView webView, String? url) {
	callbacksHandler.onPageStarted(url ?? '');
	})
	..setDidFinishNavigation((WKWebView webView, String? url) {
	callbacksHandler.onPageFinished(url ?? '');
	})
	..setDidFailNavigation((WKWebView webView, NSError error) {
	callbacksHandler.onWebResourceError(_toWebResourceError(error));
	})
	..setDidFailProvisionalNavigation((WKWebView webView, NSError error) {
	callbacksHandler.onWebResourceError(_toWebResourceError(error));
	})
	..setWebViewWebContentProcessDidTerminate((WKWebView webView) {
	callbacksHandler.onWebResourceError(WebResourceError(
	errorCode: WKErrorCode.webContentProcessTerminated,
	// Value from https://developer.apple.com/documentation/webkit/wkerrordomain?language=objc.
	domain: 'WKErrorDomain',
	description: '',
	errorType: WebResourceErrorType.webContentProcessTerminated,
	));
	});

	Future<void> _setCreationParams(
	CreationParams params, {
	required WKWebViewConfiguration configuration,
	}) async {
	_setWebViewConfiguration(
	configuration,
	allowsInlineMediaPlayback: params.webSettings?.allowsInlineMediaPlayback,
	autoMediaPlaybackPolicy: params.autoMediaPlaybackPolicy,
	);

	webView = webViewProxy.createWebView(configuration);

	webView.setUIDelegate(uiDelegate);
	uiDelegate.setOnCreateWebView((
	WKWebViewConfiguration configuration,
	WKNavigationAction navigationAction,
	) {
	if (!navigationAction.targetFrame.isMainFrame) {
	webView.loadRequest(navigationAction.request);
	}
	});

	await addJavascriptChannels(params.javascriptChannelNames);

	webView.setNavigationDelegate(navigationDelegate);

	if (params.userAgent != null) {
	webView.setCustomUserAgent(params.userAgent);
	}

	if (params.webSettings != null) {
	updateSettings(params.webSettings!);
	}

	if (params.backgroundColor != null) {
	webView.setOpaque(false);
	webView.setBackgroundColor(Colors.transparent);
	webView.scrollView.setBackgroundColor(params.backgroundColor);
	}

	if (params.initialUrl != null) {
	await loadUrl(params.initialUrl!, null);
	}
	}

	void _setWebViewConfiguration(
	WKWebViewConfiguration configuration, {
	required bool? allowsInlineMediaPlayback,
	required AutoMediaPlaybackPolicy autoMediaPlaybackPolicy,
	}) {
	if (allowsInlineMediaPlayback != null) {
	configuration.setAllowsInlineMediaPlayback(allowsInlineMediaPlayback);
	}

	late final bool requiresUserAction;
	switch (autoMediaPlaybackPolicy) {
	case AutoMediaPlaybackPolicy.require_user_action_for_all_media_types:
	requiresUserAction = true;
	break;
	case AutoMediaPlaybackPolicy.always_allow:
	requiresUserAction = false;
	break;
	}

	configuration
	.setMediaTypesRequiringUserActionForPlayback(<WKAudiovisualMediaType>{
	if (requiresUserAction) WKAudiovisualMediaType.all,
	if (!requiresUserAction) WKAudiovisualMediaType.none,
	});
	}

	@override
	Future<void> loadHtmlString(String html, {String? baseUrl}) {
	return webView.loadHtmlString(html, baseUrl: baseUrl);
	}

	@override
	Future<void> loadFile(String absoluteFilePath) async {
	await webView.loadFileUrl(
	absoluteFilePath,
	readAccessUrl: path.dirname(absoluteFilePath),
	);
	}

	@override
	Future<void> clearCache() {
	return webView.configuration.websiteDataStore.removeDataOfTypes(
	<WKWebsiteDataType>{
	WKWebsiteDataType.memoryCache,
	WKWebsiteDataType.diskCache,
	WKWebsiteDataType.offlineWebApplicationCache,
	WKWebsiteDataType.localStorage,
	},
	DateTime.fromMillisecondsSinceEpoch(0),
	);
	}

	@override
	Future<void> loadFlutterAsset(String key) async {
	assert(key.isNotEmpty);
	return webView.loadFlutterAsset(key);
	}

	@override
	Future<void> loadUrl(String url, Map<String, String>? headers) async {
	final NSUrlRequest request = NSUrlRequest(
	url: url,
	allHttpHeaderFields: headers ?? <String, String>{},
	);
	return webView.loadRequest(request);
	}

	@override
	Future<void> loadRequest(WebViewRequest request) async {
	if (!request.uri.hasScheme) {
	throw ArgumentError('WebViewRequest#uri is required to have a scheme.');
	}

	final NSUrlRequest urlRequest = NSUrlRequest(
	url: request.uri.toString(),
	allHttpHeaderFields: request.headers,
	httpMethod: describeEnum(request.method),
	httpBody: request.body,
	);

	return webView.loadRequest(urlRequest);
	}

	@override
	Future<bool> canGoBack() => webView.canGoBack();

	@override
	Future<bool> canGoForward() => webView.canGoForward();

	@override
	Future<void> goBack() => webView.goBack();

	@override
	Future<void> goForward() => webView.goForward();

	@override
	Future<void> reload() => webView.reload();

	@override
	Future<String> evaluateJavascript(String javascript) async {
	final Object? result = await webView.evaluateJavaScript(javascript);
	// The legacy implementation of webview_flutter_wkwebview would convert
	// objects to strings before returning them to Dart. This method attempts
	// to converts Dart objects to Strings the way it is done in Objective-C
	// to avoid breaking users expecting the same String format.
	return _asObjectiveCString(result);
	}

	@override
	Future<void> runJavascript(String javascript) async {
	try {
	await webView.evaluateJavaScript(javascript);
	} on PlatformException catch (exception) {
	// WebKit will throw an error when the type of the evaluated value is
	// unsupported. This also goes for `null` and `undefined` on iOS 14+. For
	// example, when running a void function. For ease of use, this specific
	// error is ignored when no return value is expected.
	// TODO(bparrishMines): Ensure the platform code includes the NSError in
	// the FlutterError.details.
	if (exception.details is! NSError \|\|
	exception.details.code !=
	WKErrorCode.javaScriptResultTypeIsUnsupported) {
	rethrow;
	}
	}
	}

	@override
	Future<String> runJavascriptReturningResult(String javascript) async {
	final Object? result = await webView.evaluateJavaScript(javascript);
	if (result == null) {
	throw ArgumentError(
	'Result of JavaScript execution returned a `null` value. '
	'Use `runJavascript` when expecting a null return value.',
	);
	}
	return result.toString();
	}

	@override
	Future<String?> getTitle() => webView.getTitle();

	@override
	Future<void> scrollTo(int x, int y) async {
	webView.scrollView.setContentOffset(Point<double>(
	x.toDouble(),
	y.toDouble(),
	));
	}

	@override
	Future<void> scrollBy(int x, int y) async {
	await webView.scrollView.scrollBy(Point<double>(
	x.toDouble(),
	y.toDouble(),
	));
	}

	@override
	Future<int> getScrollX() async {
	final Point<double> offset = await webView.scrollView.getContentOffset();
	return offset.x.toInt();
	}

	@override
	Future<int> getScrollY() async {
	final Point<double> offset = await webView.scrollView.getContentOffset();
	return offset.y.toInt();
	}

	@override
	Future<void> updateSettings(WebSettings setting) async {
	await Future.wait(<Future<void>>[
	_setUserAgent(setting.userAgent),
	if (setting.hasNavigationDelegate != null)
	_setHasNavigationDelegate(setting.hasNavigationDelegate!),
	if (setting.hasProgressTracking != null)
	_setHasProgressTracking(setting.hasProgressTracking!),
	if (setting.javascriptMode != null)
	_setJavaScriptMode(setting.javascriptMode!),
	if (setting.zoomEnabled != null) _setZoomEnabled(setting.zoomEnabled!),
	if (setting.gestureNavigationEnabled != null)
	webView.setAllowsBackForwardNavigationGestures(
	setting.gestureNavigationEnabled!,
	),
	]);
	}

	@override
	Future<void> addJavascriptChannels(Set<String> javascriptChannelNames) async {
	await Future.wait<void>(
	javascriptChannelNames.where(
	(String channelName) {
	return !_scriptMessageHandlers.containsKey(channelName);
	},
	).map<Future<void>>(
	(String channelName) {
	final WKScriptMessageHandler handler =
	webViewProxy.createScriptMessageHandler()
	..setDidReceiveScriptMessage((
	WKUserContentController userContentController,
	WKScriptMessage message,
	) {
	javascriptChannelRegistry.onJavascriptChannelMessage(
	message.name,
	message.body!.toString(),
	);
	});
	_scriptMessageHandlers[channelName] = handler;

	final String wrapperSource =
	'window.$channelName = webkit.messageHandlers.$channelName;';
	final WKUserScript wrapperScript = WKUserScript(
	wrapperSource,
	WKUserScriptInjectionTime.atDocumentStart,
	isMainFrameOnly: false,
	);
	webView.configuration.userContentController
	.addUserScript(wrapperScript);
	return webView.configuration.userContentController
	.addScriptMessageHandler(
	handler,
	channelName,
	);
	},
	),
	);
	}

	@override
	Future<void> removeJavascriptChannels(
	Set<String> javascriptChannelNames,
	) async {
	if (javascriptChannelNames.isEmpty) {
	return;
	}

	await _resetUserScripts(removedJavaScriptChannels: javascriptChannelNames);
	}

	Future<void> _setHasNavigationDelegate(bool hasNavigationDelegate) {
	if (hasNavigationDelegate) {
	return navigationDelegate.setDecidePolicyForNavigationAction(
	(WKWebView webView, WKNavigationAction action) async {
	final bool allow = await callbacksHandler.onNavigationRequest(
	url: action.request.url,
	isForMainFrame: action.targetFrame.isMainFrame,
	);

	return allow
	? WKNavigationActionPolicy.allow
	: WKNavigationActionPolicy.cancel;
	});
	} else {
	return navigationDelegate.setDecidePolicyForNavigationAction(null);
	}
	}

	Future<void> _setHasProgressTracking(bool hasProgressTracking) {
	if (hasProgressTracking) {
	webView.setObserveValue((
	String keyPath,
	NSObject object,
	Map<NSKeyValueChangeKey, Object?> change,
	) {
	final double progress = change[NSKeyValueChangeKey.newValue]! as double;
	callbacksHandler.onProgress((progress * 100).round());
	});
	return webView.addObserver(
	webView,
	keyPath: 'estimatedProgress',
	options: <NSKeyValueObservingOptions>{
	NSKeyValueObservingOptions.newValue,
	},
	);
	} else {
	webView.setObserveValue(null);
	return webView.removeObserver(webView, keyPath: 'estimatedProgress');
	}
	}

	Future<void> _setJavaScriptMode(JavascriptMode mode) {
	switch (mode) {
	case JavascriptMode.disabled:
	return webView.configuration.preferences.setJavaScriptEnabled(false);
	case JavascriptMode.unrestricted:
	return webView.configuration.preferences.setJavaScriptEnabled(true);
	}
	}

	Future<void> _setUserAgent(WebSetting<String?> userAgent) async {
	if (userAgent.isPresent) {
	await webView.setCustomUserAgent(userAgent.value);
	}
	}

	Future<void> _setZoomEnabled(bool zoomEnabled) async {
	if (_zoomEnabled == zoomEnabled) {
	return;
	}

	_zoomEnabled = zoomEnabled;
	if (!zoomEnabled) {
	return _disableZoom();
	}

	return _resetUserScripts();
	}

	Future<void> _disableZoom() {
	const WKUserScript userScript = WKUserScript(
	"var meta = document.createElement('meta');\n"
	"meta.name = 'viewport';\n"
	"meta.content = 'width=device-width, initial-scale=1.0, maximum-scale=1.0, "
	"user-scalable=no';\n"
	"var head = document.getElementsByTagName('head')[0];head.appendChild(meta);",
	WKUserScriptInjectionTime.atDocumentEnd,
	isMainFrameOnly: true,
	);
	return webView.configuration.userContentController
	.addUserScript(userScript);
	}

	// WkWebView does not support removing a single user script, so all user
	// scripts and all message handlers are removed instead. And the JavaScript
	// channels that shouldn't be removed are re-registered. Note that this
	// workaround could interfere with exposing support for custom scripts from
	// applications.
	Future<void> _resetUserScripts({
	Set<String> removedJavaScriptChannels = const <String>{},
	}) async {
	webView.configuration.userContentController.removeAllUserScripts();
	// TODO(bparrishMines): This can be replaced with
	// `removeAllScriptMessageHandlers` once Dart supports runtime version
	// checking. (e.g. The equivalent to @availability in Objective-C.)
	_scriptMessageHandlers.keys.forEach(
	webView.configuration.userContentController.removeScriptMessageHandler,
	);

	removedJavaScriptChannels.forEach(_scriptMessageHandlers.remove);
	final Set<String> remainingNames = _scriptMessageHandlers.keys.toSet();
	_scriptMessageHandlers.clear();

	await Future.wait(<Future<void>>[
	addJavascriptChannels(remainingNames),
	// Zoom is disabled with a WKUserScript, so this adds it back if it was
	// removed above.
	if (!_zoomEnabled) _disableZoom(),
	]);
	}

	static WebResourceError _toWebResourceError(NSError error) {
	WebResourceErrorType? errorType;

	switch (error.code) {
	case WKErrorCode.unknown:
	errorType = WebResourceErrorType.unknown;
	break;
	case WKErrorCode.webContentProcessTerminated:
	errorType = WebResourceErrorType.webContentProcessTerminated;
	break;
	case WKErrorCode.webViewInvalidated:
	errorType = WebResourceErrorType.webViewInvalidated;
	break;
	case WKErrorCode.javaScriptExceptionOccurred:
	errorType = WebResourceErrorType.javaScriptExceptionOccurred;
	break;
	case WKErrorCode.javaScriptResultTypeIsUnsupported:
	errorType = WebResourceErrorType.javaScriptResultTypeIsUnsupported;
	break;
	}

	return WebResourceError(
	errorCode: error.code,
	domain: error.domain,
	description: error.localizedDescription,
	errorType: errorType,
	);
	}

	String _asObjectiveCString(Object? value, {bool inContainer = false}) {
	if (value == null) {
	// An NSNull inside an NSArray or NSDictionary is represented as a String
	// differently than a nil.
	if (inContainer) {
	return '"<null>"';
	}
	return '(null)';
	} else if (value is List) {
	final List<String> stringValues = <String>[];
	for (final Object? listValue in value) {
	stringValues.add(_asObjectiveCString(listValue, inContainer: true));
	}
	return '(${stringValues.join(',')})';
	} else if (value is Map) {
	final List<String> stringValues = <String>[];
	for (final MapEntry<Object?, Object?> entry in value.entries) {
	stringValues.add(
	'${_asObjectiveCString(entry.key, inContainer: true)} '
	'= '
	'${_asObjectiveCString(entry.value, inContainer: true)}',
	);
	}
	return '{${stringValues.join(';')}}';
	}

	return value.toString();
	}
	}

	/// Handles constructing objects and calling static methods.
	///
	/// This should only be used for testing purposes.
	@visibleForTesting
	class WebViewWidgetProxy {
	/// Constructs a [WebViewWidgetProxy].
	const WebViewWidgetProxy();

	/// Constructs a [WKWebView].
	WKWebView createWebView(WKWebViewConfiguration configuration) {
	return WKWebView(configuration);
	}

	/// Constructs a [WKScriptMessageHandler].
	WKScriptMessageHandler createScriptMessageHandler() {
	return WKScriptMessageHandler();
	}

	/// Constructs a [WKUIDelegate].
	WKUIDelegate createUIDelgate() {
	return WKUIDelegate();
	}

	/// Constructs a [WKNavigationDelegate].
	WKNavigationDelegate createNavigationDelegate() {
	return WKNavigationDelegate();
	}
	}