How to render a local HTML file with flutter dart webview

I am using the webview_flutter plugin from the Flutter Team.

Steps

1. Add the dependency to pubspec.yaml:

   dependencies:
     webview_flutter: ^0.3.20+2
   

2. Put an html file in the assets folder (see this). I’ll call it help.html.

3. Get the html string in code and add it to the webview.

   import 'dart:convert';
   
   import 'package:flutter/material.dart';
   import 'package:flutter/services.dart';
   import 'package:webview_flutter/webview_flutter.dart';
   
   
   class HelpScreen extends StatefulWidget {
     @override
     HelpScreenState createState() {
       return HelpScreenState();
     }
   }
   
   class HelpScreenState extends State<HelpScreen> {
     WebViewController _controller;
   
     @override
     Widget build(BuildContext context) {
       return Scaffold(
         appBar: AppBar(title: Text('Help')),
         body: WebView(
           initialUrl: 'about:blank',
           onWebViewCreated: (WebViewController webViewController) {
             _controller = webViewController;
             _loadHtmlFromAssets();
           },
         ),
       );
     }
   
     _loadHtmlFromAssets() async {
       String fileText = await rootBundle.loadString('assets/help.html');
       _controller.loadUrl( Uri.dataFromString(
           fileText,
           mimeType: 'text/html',
           encoding: Encoding.getByName('utf-8')
       ).toString());
     }
   }
   

Notes:

• I needed to set the encoding to UTF-8 because I was getting a crash for non-ASCII characters.
• In iOS you need to add the key io.flutter.embedded_views_preview as true in the Info.plist file. Check the docs for any update on this requirement.

See also

• The Power of WebViews in Flutter