How to Make Double Press Back Button to Exit on Flutter App
Introduction
Double pressing the back button to exit an app is a common feature in many Android and iOS applications. This functionality provides a convenient way for users to confirm their intention to exit the app, preventing accidental closures. In this article, we will explore how to implement this feature in a Flutter app.
Understanding the Requirement
To implement the double press back button to exit functionality, we need to override the default back button behavior in our Flutter app. This involves listening to the back button press event and handling it manually.
Implementing Double Press Back Button
To achieve this, we will use the `WillPopScope` widget, which provides a way to override the default back button behavior. We will also use a `bool` variable to track whether the back button was pressed within a certain time limit.
“`dart
import ‘dart:async’;
import ‘package:flutter/material.dart’;
class MyHomePage extends StatefulWidget {
@override
MyHomePageState createState() => MyHomePageState();
}
class _MyHomePageState extends State
bool _doubleBackToExitPressedOnce = false;
DateTime? _currentBackPressTime;
Future
DateTime now = DateTime.now();
if (currentBackPressTime == null || now.difference(currentBackPressTime!) > Duration(seconds: 2)) {
_currentBackPressTime = now;
setState(() {
_doubleBackToExitPressedOnce = true;
});
return false;
}
if (_doubleBackToExitPressedOnce) {
return true;
}
_currentBackPressTime = now;
setState(() {
_doubleBackToExitPressedOnce = true;
});
return false;
}
@override
Widget build(BuildContext context) {
return WillPopScope(
onWillPop: _onWillPop,
child: Scaffold(
body: Center(
child: Text(‘Double press back button to exit’),
),
),
);
}
}
“`
Handling the Back Button Press
In the above code, we use the `WillPopScope` widget to override the default back button behavior. When the back button is pressed, the `_onWillPop` function is called. This function checks if the back button was pressed within the last 2 seconds. If it was, the app exits. If not, a flag is set to indicate that the back button was pressed once.
Conclusion
In this article, we learned how to implement the double press back button to exit functionality in a Flutter app. This feature provides a convenient way for users to confirm their intention to exit the app, preventing accidental closures.
FAQ
1. How do I override the default back button behavior in Flutter?
You can override the default back button behavior in Flutter by using the `WillPopScope` widget.
2. What is the purpose of the `_doubleBackToExitPressedOnce` variable?
The `_doubleBackToExitPressedOnce` variable is used to track whether the back button was pressed within a certain time limit.
3. How do I handle the back button press event in Flutter?
You can handle the back button press event in Flutter by using the `onWillPop` property of the `WillPopScope` widget.
4. What is the purpose of the `_currentBackPressTime` variable?
The `_currentBackPressTime` variable is used to track the time at which the back button was last pressed.
5. How do I set the time limit for the double press back button to exit functionality?
You can set the time limit for the double press back button to exit functionality by modifying the `Duration` object in the `_onWillPop` function.
