WebViews in Flutter - Does it really work?

Talk given at Flutter London meetup
https://www.meetup.com/FlutterLDN/events/262574231/

1. WebViews in Flutter Does it really work? Lara Martín @Lariki Flutter/Dart GDE - Android Developer
2. What is a WebView?
3. Why we need WebViews? Use cases Perform social login Show static content (e.g. FAQ) Payment confirmation Avoid for Making an app that is just a web
4. https://pub.dev/packages/webview_flutter
5. Setup # pubspec.yaml dependencies: flutter: sdk: flutter webview_flutter: ^0.3.10
6. Implementation • Not reimplemented in Dart! • Uses native WebView iOS: WKWebView Android: android.webkit.WebView • But is it a Widget? The plugin creates the native WebView And renders it in Flutter!
7. Rendering the Android WebView
8. Working Example
9. Flutter Inspector
10. Flutter Inspector
11. Flutter Inspector
12. WebView Rendering on Android AndroidView _AndroidPlatformView RenderAndroidView : RenderBox WebView renders contains … in requires WebViewFactory surface ID contains child PlatformViewController FlutterWebView : PlatformView creates WebViewFlutterPlugin registers Surface WebView contains
13. Rendering the iOS WKWebView
14. WebView Rendering on iOS • Similar to Android • RenderUiKitView will render a surface created in the PlatformViewIOS • Passes an ID
15. WebView Widget
16. WebView Widget • InitialUrl • javaScriptMode • onWebViewCreated • onPageFinished • gestureRecognizers • navigationDelegate • javaScriptChannels
17. WebView Widget • InitialUrl • javaScriptMode • onWebViewCreated • onPageFinished • gestureRecognizers • navigationDelegate • javaScriptChannels
18. WebView Widget: initialUrl WebView(),
19. WebView Widget: initialUrl WebView( initialUrl: “https://www.flutter.dev/", ),
20. WebView Widget • InitialUrl • javaScriptMode • onWebViewCreated • onPageFinished • gestureRecognizers • navigationDelegate • javaScriptChannels
21. WebView Widget: javaScriptMode WebView( initialUrl: … javascriptMode: JavascriptMode.unrestricted, ),
22. WebView Widget • InitialUrl • javaScriptMode • onWebViewCreated • onPageFinished • gestureRecognizers • navigationDelegate • javaScriptChannels
23. WebView Widget: onWebViewCreated WebView( initialUrl: … javascriptMode: … onWebViewCreated: (WebViewController controller) { _controller = controller; }, ),
24. WebViewController • loadUrl(String url) • currentUrl() • canGoBack() • canGoForward() • goBack() • goForward() • reload() • clearCache()
25. WebViewController • loadUrl(String url) • currentUrl() • canGoBack() • canGoForward() • goBack() • goForward() • reload() • clearCache()
26. WebViewController: reload onPressed: () async { await _controller.reload(); }
27. WebView Widget • InitialUrl • javaScriptMode • onWebViewCreated • onPageFinished • gestureRecognizers • navigationDelegate • javaScriptChannels
28. WebView Widget: onPageFinished WebView( initialUrl: … javascriptMode: … onWebViewCreated: … onPageFinished: (url) { // use the URL } ),
29. WebView Widget • InitialUrl • javaScriptMode • onWebViewCreated • onPageFinished • gestureRecognizers • navigationDelegate • javaScriptChannels
30. WebView Widget • InitialUrl • javaScriptMode • onWebViewCreated • onPageFinished • gestureRecognizers • navigationDelegate • javaScriptChannels The Power of WebViews in Flutter, by Emily Fortuna https:/ /medium.com/flutter-io/the-power-of-webviews-in-flutter- a56234b57df2
31. WebView Widget • InitialUrl • javaScriptMode • onWebViewCreated • onPageFinished • gestureRecognizers • navigationDelegate • javaScriptChannels
32. WebView Widget: NavigationDelegate typedef NavigationDecision NavigationDelegate(NavigationRequest n);
33. WebView Widget: NavigationDelegate WebView( navigationDelegate: (request) { bool isHost = request.url.startsWith( “https://flutter.dev”); if (isHost) return NavigationDecision.navigate; else return NavigationDecision.prevent; } );
34. WebView Widget • InitialUrl • javaScriptMode • onWebViewCreated • onPageFinished • gestureRecognizers • navigationDelegate • javaScriptChannels
35. WebView Widget: javaScriptChannels WebView( javascriptChannels: {_channel}, );
36. WebView Widget: javaScriptChannels WebView( javascriptChannels: {_channel}, ); var _channel = JavascriptChannel( name: 'LaraDemo', onMessageReceived: (JavascriptMessage message) { print(message.message); });
37. WebView Widget: javaScriptChannels WebView( javascriptChannels: {_channel}, ); var _channel = JavascriptChannel( name: 'LaraDemo', onMessageReceived: (JavascriptMessage message) { print(message.message); });
38. WebView Widget: javaScriptChannels WebView( javascriptChannels: {_channel}, ); var _channel = JavascriptChannel( name: 'LaraDemo', onMessageReceived: (JavascriptMessage message) { print(message.message); });
39. WebView Widget: javaScriptChannels WebView( javascriptChannels: {_channel}, ); var _channel = JavascriptChannel( name: 'LaraDemo', onMessageReceived: (JavascriptMessage message) { print(message.message); });
40. WebView Widget: javaScriptChannels var _channel = JavascriptChannel( name: 'LaraDemo', onMessageReceived: (JavascriptMessage message) { print(message.message); }); Flutter side <script> LaraDemo.postMessage('Hello'); </script> HTML side
41. Limitations
42. Input Fields https:/ /github.com/flutter/flutter/issues/19718 FIXED!-ish
43. Text Selection https:/ /github.com/flutter/flutter/issues/24584
44. Performance AndroidView is costly
45. What’s next
46. Setting a custom UserAgent https:/ /github.com/flutter/plugins/pull/968
47. Page loaded correctly https:/ /github.com/flutter/plugins/pull/1389
48. Loading an HTML string https:/ /github.com/flutter/plugins/pull/1312
49. Community Plugin
50. WebView community plugin https:/ /pub.dev/packages/flutter_webview_plugin
51. WebView community plugin MaterialApp( home: WebviewScaffold( url: url, appBar: AppBar( title: Text("community webview"), ), ), );
52. WebView community plugin https:/ /pub.dev/packages/flutter_webview_plugin deprecated?
53. Contributing
54. Contributing
55. Contributing
56. Flutter is open-source. Submit a pull request!
57. 57 L a r a M a r t í n F l u t t e r / D a r t G D E 
 A n d r o i d D e v e l o p e r @ L a r i k i Thank You!