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". The following second press, app exits. Of course, the time between two press must be not long.

How to do it in flutter?

Answer 1

This is an example of my code (I've used "fluttertoast" for showing toast message, you can use snackbar or alert or anything else)

DateTime currentBackPressTime;  @override Widget build(BuildContext context) {   return Scaffold(     ...     body: WillPopScope(child: getBody(), onWillPop: onWillPop),   ); }  Future<bool> onWillPop() {     DateTime now = DateTime.now();     if (currentBackPressTime == null ||          now.difference(currentBackPressTime) > Duration(seconds: 2)) {       currentBackPressTime = now;       Fluttertoast.showToast(msg: exit_warning);       return Future.value(false);     }     return Future.value(true);   } 

Answer 2

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'),           ),         ),       ),     );   } } 

The solution below must be considered deprecated because it causes a few issues that were tackled in the package mentioned. For instance, the app closes if the snack bar was dismissed by the user (see hcbpassos/double_back_to_close_app#2).

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<Foo> {   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<bool> 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;   } }