What is the difference between didChangeDependencies and initState?

Question

I am new to flutter and when I want to call my context in InitState it throws an error : which is about BuildContext.inheritFromWidgetOfExactType but then I use did

Answer 1

This is a supplemental answer showing what the OP described.

The State class of a StatefulWidget has a context property. This build context is first available in didChangeDependencies. Trying to use context in initState will cause an error.

class HomeWidget extends StatefulWidget {
  const HomeWidget({Key key}) : super(key: key);

  @override
  _HomeWidgetState createState() => _HomeWidgetState();
}

class _HomeWidgetState extends State {
  @override
  void initState() {
    print('initState');
    // print(Theme.of(context));        // ERROR!
    super.initState();
  }

  @override
  void didChangeDependencies() {
    print('didChangeDependencies');
    print(Theme.of(context));           // OK
    super.didChangeDependencies();
  }

  @override
  Widget build(BuildContext context) {
    print('build');
    print(Theme.of(context));           // OK
    return Container();
  }
}

Running that gives the print statements in the following order:

initState
didChangeDependencies
ThemeData#93b06
build
ThemeData#93b06

See also Working with didChangeDependencies() in Flutter