`vsync` property in TabController constructor

Question

According to this: sample code

I created my own implementation of TabController:

void main() {   runApp(new MyApp()); }  class MyApp extends StatefulWidget {    @override   _MyAppState createState() => new _MyAppState(); }  class _MyAppState extends State<MyApp> {    TabController _tabController;    @override   void initState() {     super.initState();     _tabController = new TabController(vsync: this, length: choices.length);   }    @override   void dispose() {     _tabController.dispose();     super.dispose();   }    @override   Widget build(BuildContext context) {     return new MaterialApp(       home: new Scaffold(         bottomNavigationBar: new Material(           color: Colors.blue,           child: new TabBar(             controller: _tabController,             isScrollable: false,             tabs: choices.map((Choice choice) {               return new Tab(                 text: null,                 icon: new Icon(choice.icon),               );             }).toList(),           ),         ),         appBar: new AppBar(           title: const Text('Swap'),         ),         body: new TabBarView(           controller: _tabController,           children: choices.map((Choice choice) {             return new Padding(               padding: const EdgeInsets.all(16.0),               child: new ChoiceCard(choice: choice),             );           }).toList(),         ),       ),     );   } } 

In line: _tabController = new TabController(vsync: this, length: choices.length); I got error this message:

error: The argument type '_MyAppState' can't be assigned to the parameter type 'TickerProvider'. (argument_type_not_assignable at [swap] lib/main.dart:24)

What is wrong with my code?

Answer 1

Add with TickerProviderStateMixin to the end of your State’s class declaration.