如果您希望仅第一次显示Introo屏幕,则需要在本地保存该用户已经看到的Introo.
对于这样的事情,你可以用Shared Preference.有一个flutter package的共享偏好,你可以使用
EDITED:
Please refer to the below complete tested code to understand how to use it:
import 'dart:async';
import 'package:after_layout/after_layout.dart';
import 'package:flutter/material.dart';
import 'package:shared_preferences/shared_preferences.dart';
void main() => runApp(new MyApp());
class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
return new MaterialApp(
color: Colors.blue,
home: new Splash(),
);
}
}
class Splash extends StatefulWidget {
@override
SplashState createState() => new SplashState();
}
class SplashState extends State<Splash> with AfterLayoutMixin<Splash> {
Future checkFirstSeen() async {
SharedPreferences prefs = await SharedPreferences.getInstance();
bool _seen = (prefs.getBool('seen') ?? false);
if (_seen) {
Navigator.of(context).pushReplacement(
new MaterialPageRoute(builder: (context) => new Home()));
} else {
await prefs.setBool('seen', true);
Navigator.of(context).pushReplacement(
new MaterialPageRoute(builder: (context) => new IntroScreen()));
}
}
@override
void afterFirstLayout(BuildContext context) => checkFirstSeen();
@override
Widget build(BuildContext context) {
return new Scaffold(
body: new Center(
child: new Text('Loading...'),
),
);
}
}
class Home extends StatelessWidget {
@override
Widget build(BuildContext context) {
return new Scaffold(
appBar: new AppBar(
title: new Text('Hello'),
),
body: new Center(
child: new Text('This is the second page'),
),
);
}
}
class IntroScreen extends StatelessWidget {
@override
Widget build(BuildContext context) {
return new Scaffold(
appBar: new AppBar(
title: new Text('IntroScreen'),
),
body: new Center(
child: new Text('This is the IntroScreen'),
),
);
}
}
感谢Ben B注意到initState
中延迟的错误使用.我之所以使用delay
,是因为有时initState
内部的上下文并不是立即准备好的.
现在我用afterFirstLayout
代替了它,它已经准备好了.您将需要安装软件包after_layout.