Flutter 플러터에서 "뒤로" 버튼을 무시하는 방법은 무엇인가요? [중복], How To Override the “Back” button in Flutter? [duplicate]

질문

On my Home widget, when user taps system back button, I want to show a confirmation dialog asking "Do you want to exit the App?"

I don't understand how I should override or handle the system back button.

답변

WillPopScope을(를) 사용하여 이를 달성할 수 있습니다.

예시:

import 'dart:async';

import 'package:flutter/material.dart';

class HomePage extends StatefulWidget {
  HomePage({Key key, this.title}) :super(key: key);

  final String title;

  @override
  State<StatefulWidget> createState() => new _HomePageState();
}

class _HomePageState extends State<HomePage> {

  Future<bool> _onWillPop() async {
    return (await showDialog(
      context: context,
      builder: (context) => new AlertDialog(
        title: new Text('Are you sure?'),
        content: new Text('Do you want to exit an App'),
        actions: <Widget>[
          TextButton(
            onPressed: () => Navigator.of(context).pop(false),
            child: new Text('No'),
          ),
          TextButton(
            onPressed: () => Navigator.of(context).pop(true),
            child: new Text('Yes'),
          ),
        ],
      ),
    )) ?? false;
  }

  @override
  Widget build(BuildContext context) {
    return new WillPopScope(
      onWillPop: _onWillPop,
      child: new Scaffold(
        appBar: new AppBar(
          title: new Text("Home Page"),
        ),
        body: new Center(
          child: new Text("Home Page"),
        ),
      ),
    );
  }
}

??-operator는 null을 확인합니다. 여기를 참조하십시오. 이것은 showDialog가 대화 상자 외부를 클릭하면 null을 반환하므로 이 경우 false가 반환되기 때문에 중요합니다.