WebView for Flutter #

A Flutter plugin that provides a WebView widget.

On iOS the WebView widget is backed by a WKWebView. On Android the WebView widget is backed by a WebView.

Usage #

Add webview_flutter as a dependency in your pubspec.yaml file.

You can now display a WebView by:

1. Instantiating a WebViewController.

controller = WebViewController()
  ..setJavaScriptMode(JavaScriptMode.unrestricted)
  ..setBackgroundColor(const Color(0x00000000))
  ..setNavigationDelegate(
    NavigationDelegate(
      onProgress: (int progress) {
        // Update loading bar.
      },
      onPageStarted: (String url) {},
      onPageFinished: (String url) {},
      onWebResourceError: (WebResourceError error) {},
      onNavigationRequest: (NavigationRequest request) {
        if (request.url.startsWith('https://www.youtube.com/')) {
          return NavigationDecision.prevent;
        }
        return NavigationDecision.navigate;
      },
    ),
  )
  ..loadRequest(Uri.parse('https://flutter.cn'));

2. Passing the controller to a WebViewWidget.

@override
Widget build(BuildContext context) {
  return Scaffold(
    appBar: AppBar(title: const Text('Flutter Simple Example')),
    body: WebViewWidget(controller: controller),
  );
}

See the Dartdocs for WebViewController and WebViewWidget for more details.

Android Platform Views #

This plugin uses Platform Views to embed the Android’s WebView within the Flutter app.

You should however make sure to set the correct minSdkVersion in android/app/build.gradle if it was previously lower than 19:

android {
    defaultConfig {
        minSdkVersion 19
    }
}

Platform-Specific Features #

Many classes have a subclass or an underlying implementation that provides access to platform-specific features.

To access platform-specific features, start by adding the platform implementation packages to your app or package:

• Android: webview_flutter_android
• iOS: webview_flutter_wkwebview

Next, add the imports of the implementation packages to your app or package:

// Import for Android features.
import 'package:webview_flutter_android/webview_flutter_android.dart';
// Import for iOS features.
import 'package:webview_flutter_wkwebview/webview_flutter_wkwebview.dart';

Now, additional features can be accessed through the platform implementations. Classes WebViewController, WebViewWidget, NavigationDelegate, and WebViewCookieManager pass their functionality to a class provided by the current platform. Below are a couple of ways to access additional functionality provided by the platform and is followed by an example.

1. Pass a creation params class provided by a platform implementation to a fromPlatformCreationParams constructor (e.g. WebViewController.fromPlatformCreationParams, WebViewWidget.fromPlatformCreationParams, etc.).
2. Call methods on a platform implementation of a class by using the platform field (e.g. WebViewController.platform, WebViewWidget.platform, etc.).

Below is an example of setting additional iOS and Android parameters on the WebViewController.

late final PlatformWebViewControllerCreationParams params;
if (WebViewPlatform.instance is WebKitWebViewPlatform) {
  params = WebKitWebViewControllerCreationParams(
    allowsInlineMediaPlayback: true,
    mediaTypesRequiringUserAction: const <PlaybackMediaTypes>{},
  );
} else {
  params = const PlatformWebViewControllerCreationParams();
}

final WebViewController controller =
    WebViewController.fromPlatformCreationParams(params);
// ···
if (controller.platform is AndroidWebViewController) {
  AndroidWebViewController.enableDebugging(true);
  (controller.platform as AndroidWebViewController)
      .setMediaPlaybackRequiresUserGesture(false);
}

See https://pub.flutter-io.cn/documentation/webview_flutter_android/latest/webview_flutter_android/webview_flutter_android-library.html for more details on Android features.

See https://pub.flutter-io.cn/documentation/webview_flutter_wkwebview/latest/webview_flutter_wkwebview/webview_flutter_wkwebview-library.html for more details on iOS features.

Enable Material Components for Android #

To use Material Components when the user interacts with input elements in the WebView, follow the steps described in the Enabling Material Components instructions.

Setting custom headers on POST requests #

Currently, setting custom headers when making a post request with the WebViewController's loadRequest method is not supported on Android. If you require this functionality, a workaround is to make the request manually, and then load the response data using loadHtmlString instead.

Migrating from 3.0 to 4.0 #

Instantiating WebViewController #

In version 3.0 and below, WebViewController could only be retrieved in a callback after the WebView was added to the widget tree. Now, WebViewController must be instantiated and can be used before it is added to the widget tree. See Usage section above for an example.

Replacing WebView Functionality #

The WebView class has been removed and its functionality has been split into WebViewController and WebViewWidget.

WebViewController handles all functionality that is associated with the underlying web view provided by each platform. (e.g., loading a url, setting the background color of the underlying platform view, or clearing the cache).

WebViewWidget takes a WebViewController and handles all Flutter widget related functionality (e.g., layout direction, gesture recognizers).

See the Dartdocs for WebViewController and WebViewWidget for more details.

PlatformView Implementation on Android #

The PlatformView implementation for Android is currently no longer configurable. It uses Texture Layer Hybrid Composition on versions 23+ and automatically fallbacks to Hybrid Composition for version 19-23. See https://github.com/flutter/flutter/issues/108106 for progress on manually switching to Hybrid Composition on versions 23+.

API Changes #

Below is a non-exhaustive list of changes to the API:

• WebViewController.clearCache no longer clears local storage. Please use WebViewController.clearLocalStorage.
• WebViewController.clearCache no longer reloads the page.
• WebViewController.loadUrl has been removed. Please use WebViewController.loadRequest.
• WebViewController.evaluateJavascript has been removed. Please use WebViewController.runJavaScript or WebViewController.runJavaScriptReturningResult.
• WebViewController.getScrollX and WebViewController.getScrollY have been removed and have been replaced by WebViewController.getScrollPosition.
• WebViewController.runJavaScriptReturningResult now returns an Object and not a String. This will attempt to return a bool or num if the return value can be parsed.
• CookieManager is replaced by WebViewCookieManager.
• NavigationDelegate.onWebResourceError callback includes errors that are not from the main frame. Use the WebResourceError.isForMainFrame field to filter errors.
• The following fields from WebView have been moved to NavigationDelegate. They can be added to a WebView with WebViewController.setNavigationDelegate.
  • WebView.navigationDelegate -> NavigationDelegate.onNavigationRequest
  • WebView.onPageStarted -> NavigationDelegate.onPageStarted
  • WebView.onPageFinished -> NavigationDelegate.onPageFinished
  • WebView.onProgress -> NavigationDelegate.onProgress
  • WebView.onWebResourceError -> NavigationDelegate.onWebResourceError
• The following fields from WebView have been moved to WebViewController:
  • WebView.javascriptMode -> WebViewController.setJavaScriptMode
  • WebView.javascriptChannels -> WebViewController.addJavaScriptChannel/WebViewController.removeJavaScriptChannel
  • WebView.zoomEnabled -> WebViewController.enableZoom
  • WebView.userAgent -> WebViewController.setUserAgent
  • WebView.backgroundColor -> WebViewController.setBackgroundColor
• The following features have been moved to an Android implementation class. See section Platform-Specific Features for details on accessing Android platform specific features.
  • WebView.debuggingEnabled -> static AndroidWebViewController.enableDebugging
  • WebView.initialMediaPlaybackPolicy -> AndroidWebViewController.setMediaPlaybackRequiresUserGesture
• The following features have been moved to an iOS implementation class. See section Platform-Specific Features for details on accessing iOS platform specific features.
  • WebView.gestureNavigationEnabled -> WebKitWebViewController.setAllowsBackForwardNavigationGestures
  • WebView.initialMediaPlaybackPolicy -> WebKitWebViewControllerCreationParams.mediaTypesRequiringUserAction
  • WebView.allowsInlineMediaPlayback -> WebKitWebViewControllerCreationParams.allowsInlineMediaPlayback