How to write a double back button pressed to exit app using flutter

Question

I\'m new to flutter, and I saw many android apps can exit when double press back button.

The first time press back button, app shows a toast\"press again to exit app

Answer 1

You can try this package.

Inside a Scaffold that wraps all your Widgets, place the DoubleBackToCloseApp passing a SnackBar:

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        body: DoubleBackToCloseApp(
          child: Home(),
          snackBar: const SnackBar(
            content: Text('Tap back again to leave'),
          ),
        ),
      ),
    );
  }
}

Old answer

You can also opt for a solution involving SnackBar. It's not as simple as Andrey Turkovsky's answer, but it's quite more elegant and you won't depend on a library.

class _FooState extends State {
  static const snackBarDuration = Duration(seconds: 3);

  final snackBar = SnackBar(
    content: Text('Press back again to leave'),
    duration: snackBarDuration,
  );

  DateTime backButtonPressTime;

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      // The BuildContext must be from one of the Scaffold's children.
      body: Builder(
        builder: (context) {
          return WillPopScope(
            onWillPop: () => handleWillPop(context),
            child: Text('Place your child here'),
          );
        },
      ),
    );
  }

  Future handleWillPop(BuildContext context) async {
    final now = DateTime.now();
    final backButtonHasNotBeenPressedOrSnackBarHasBeenClosed =
        backButtonPressTime == null ||
            now.difference(backButtonPressTime) > snackBarDuration;

    if (backButtonHasNotBeenPressedOrSnackBarHasBeenClosed) {
      backButtonPressTime = now;
      Scaffold.of(context).showSnackBar(snackBar);
      return false;
    }

    return true;
  }
}