前端 - flutter 如何更新dialog UI？

Question

我有一个弹窗想显示5秒后4秒后3秒后2秒后1秒后自动跳转的提示，但是这个秒数怎么更新，就是弹窗一打开就自动倒计时，不用按钮触发

Answer 1

import 'dart:async';import 'package:flutter/material.dart';void main() {  runApp(MyApp());}class MyApp extends StatelessWidget {  @override  Widget build(BuildContext context) {    return MaterialApp(      home: Scaffold(        appBar: AppBar(          title: Text('Countdown Dialog'),        ),        body: Center(          child: RaisedButton(            child: Text('Show Dialog'),            onPressed: () {              showDialog(                context: context,                builder: (context) => CountdownDialog(),              );            },          ),        ),      ),    );  }}class CountdownDialog extends StatefulWidget {  @override  _CountdownDialogState createState() => _CountdownDialogState();}class _CountdownDialogState extends State<CountdownDialog> {  int countdown = 5;  @override  void initState() {    super.initState();    Timer.periodic(Duration(seconds: 1), (timer) {      if (countdown == 0) {        timer.cancel();        Navigator.of(context).pop();      } else {        setState(() {          countdown--;        });      }    });  }  @override  Widget build(BuildContext context) {    return AlertDialog(      title: Text('Countdown Dialog'),      content: Text('Closing in $countdown seconds...'),    );  }}