Flutter入门画面只有一次 [英] Flutter Onboarding Screen only one time
本文介绍了Flutter入门画面只有一次的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我是扑扑和飞镖的新手，我试图制作一个带有3页入门屏幕的应用程序，并且当用户已经打开一次应用程序时，我试图跳过入门屏幕。我看到了一些与共享首选项类似的内容，但无法使其正常工作。
i am new to flutter and dart and i am trying to make an app with an onboarding screen with 3 pages and i am trying to skip the onboarding screen when the user has already opened the app once. I have seen something similar with the shared preferences, but i couldn't make it work.
这是我的入职屏幕：
class OnboardingScreen extends StatefulWidget {
@override
_OnboardingScreenState createState() => _OnboardingScreenState();
}
class _OnboardingScreenState extends State<OnboardingScreen> {
final int _numPages = 3;
final PageController _pageController = PageController(initialPage: 0);
int _currentPage = 0;
List<Widget> _buildPageIndicator() {
List<Widget> list = [];
for (int i = 0; i < _numPages; i++) {
list.add(i == _currentPage ? _indicator(true) : _indicator(false));
}
return list;
}
Widget _indicator(bool isActive) {
return AnimatedContainer(
duration: Duration(milliseconds: 150),
margin: EdgeInsets.symmetric(horizontal: 8.0),
height: 8.0,
width: isActive ? 24.0 : 16.0,
decoration: BoxDecoration(
color: isActive ? Colors.white : Color(0xFF7B51D3),
borderRadius: BorderRadius.all(Radius.circular(12)),
),
);
}
@override
Widget build(BuildContext context) {
return Scaffold(
body: AnnotatedRegion<SystemUiOverlayStyle>(
value: SystemUiOverlayStyle.light,
child: Container(
decoration: BoxDecoration(
gradient: LinearGradient(
begin: Alignment.topCenter,
end: Alignment.bottomCenter,
stops: [0.1, 0.4, 0.7, 0.9],
colors: [
Color(0xFF3594DD),
Color(0xFF4563DB),
Color(0xFF5036D5),
Color(0xFF5B16D0),
],
),
),
child: Padding(
padding: EdgeInsets.symmetric(vertical: 40.0),
child: Column(
crossAxisAlignment: CrossAxisAlignment.stretch,
children: <Widget>[
Container(
alignment: Alignment.centerRight,
child: FlatButton(
onPressed: () => print('Skip'),
child: Text(
'Skip',
style: TextStyle(
color: Colors.white,
fontSize: 20.0,
),
),
),
),
Container(
height: 600.0,
child: PageView(
physics: ClampingScrollPhysics(),
controller: _pageController,
onPageChanged: (int page) {
setState(() {
_currentPage = page;
});
},
children: <Widget>[
Padding(
padding: EdgeInsets.all(40.0),
child: Column(
crossAxisAlignment: CrossAxisAlignment.start,
children: <Widget>[
Center(
child: Image(
image: AssetImage(
'assets/images/lorem_Ipsum.png',
),
height: 300.0,
width: 300.0,
),
),
SizedBox(height: 30.0),
Text(
'Welcome to ...',
style: kTitleStyle,
),
SizedBox(height: 15.0),
Text(
'lorem Ipsum',
style: kSubtitleStyle,
),
],
),
),
Padding(
padding: EdgeInsets.all(40.0),
child: Column(
crossAxisAlignment: CrossAxisAlignment.start,
children: <Widget>[
Center(
child: Image(
image: AssetImage(
'assets/images/lorem_Ipsum.png',
),
height: 300.0,
width: 300.0,
),
),
SizedBox(height: 30.0),
Text(
'lorem Ipsum',
style: kTitleStyle,
),
SizedBox(height: 15.0),
Text(
'lorem Ipsum',
style: kSubtitleStyle,
),
],
),
),
Padding(
padding: EdgeInsets.all(40.0),
child: Column(
crossAxisAlignment: CrossAxisAlignment.start,
children: <Widget>[
Center(
child: Image(
image: AssetImage(
'assets/images/lorem_Ipsum.png',
),
height: 300.0,
width: 300.0,
),
),
SizedBox(height: 30.0),
Text(
'lorem Ipsum',
style: kTitleStyle,
),
SizedBox(height: 15.0),
Text(
'lorem Ipsum',
style: kSubtitleStyle,
),
],
),
),
],
),
),
Row(
mainAxisAlignment: MainAxisAlignment.center,
children: _buildPageIndicator(),
),
_currentPage != _numPages - 1
? Expanded(
child: Align(
alignment: FractionalOffset.bottomRight,
child: FlatButton(
onPressed: () {
_pageController.nextPage(
duration: Duration(milliseconds: 500),
curve: Curves.ease,
);
},
child: Row(
mainAxisAlignment: MainAxisAlignment.center,
mainAxisSize: MainAxisSize.min,
children: <Widget>[
Text(
'Next',
style: TextStyle(
color: Colors.white,
fontSize: 22.0,
),
),
SizedBox(width: 10.0),
Icon(
Icons.arrow_forward,
color: Colors.white,
size: 30.0,
),
],
),
),
),
)
: Text(''),
],
),
),
),
),
bottomSheet: _currentPage == _numPages - 1
? Container(
height: 50.0,
width: double.infinity,
color: Colors.white,
child: GestureDetector(
onTap: () => print('Get Started'),
child: Center(
child: Padding(
padding: EdgeInsets.only(bottom: 5.0),
child: Text(
'Get Started',
style: TextStyle(
color: Color(0xFF5B16D0),
fontSize: 20.0,
fontWeight: FontWeight.bold,
),
),
),
),
),
)
: Text(''),
);
}
}
推荐答案
您可以在 main（）
中使用 SharedPreferences 并设置 initScreen 首次初始化时变量，设置为1表示它已初始化
并在 MyApp initialRoute中检查 initScreen 是 null 决定要走的路线
您可以在
<
You can use SharedPreferences in main()
And set a initScreen variable when first time init, set to 1 to indicate it has initialized
And In MyApp initialRoute check initScreen is null to decide which route to go
You can copy paste run full code below
代码段
int initScreen;
Future<void> main() async {
WidgetsFlutterBinding.ensureInitialized();
SharedPreferences prefs = await SharedPreferences.getInstance();
initScreen = await prefs.getInt("initScreen");
await prefs.setInt("initScreen", 1);
print('initScreen ${initScreen}');
runApp(MyApp());
}
class MyApp extends StatelessWidget {
// This widget is the root of your application.
@override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
primarySwatch: Colors.blue,
),
initialRoute: initScreen == 0 || initScreen == null ? "first" : "/",
routes: {
'/': (context) => MyHomePage(
title: "demo",
),
"first": (context) => OnboardingScreen(),
},
);
}
}
完整代码
import 'package:flutter/material.dart';
import 'package:shared_preferences/shared_preferences.dart';
import 'package:flutter/services.dart';
int initScreen;
Future<void> main() async {
WidgetsFlutterBinding.ensureInitialized();
SharedPreferences prefs = await SharedPreferences.getInstance();
initScreen = await prefs.getInt("initScreen");
await prefs.setInt("initScreen", 1);
print('initScreen ${initScreen}');
runApp(MyApp());
}
class MyApp extends StatelessWidget {
// This widget is the root of your application.
@override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
primarySwatch: Colors.blue,
),
initialRoute: initScreen == 0 || initScreen == null ? "first" : "/",
routes: {
'/': (context) => MyHomePage(
title: "demo",
),
"first": (context) => OnboardingScreen(),
},
);
}
}
class MyHomePage extends StatefulWidget {
MyHomePage({Key key, this.title}) : super(key: key);
final String title;
@override
_MyHomePageState createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage> {
int _counter = 0;
void _incrementCounter() {
setState(() {
_counter++;
});
}
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text(widget.title),
),
body: Center(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Text(
'You have pushed the button this many times:',
),
Text(
'$_counter',
style: Theme.of(context).textTheme.display1,
),
],
),
),
floatingActionButton: FloatingActionButton(
onPressed: _incrementCounter,
tooltip: 'Increment',
child: Icon(Icons.add),
),
);
}
}
class OnboardingScreen extends StatefulWidget {
@override
_OnboardingScreenState createState() => _OnboardingScreenState();
}
class _OnboardingScreenState extends State<OnboardingScreen> {
final int _numPages = 3;
final PageController _pageController = PageController(initialPage: 0);
int _currentPage = 0;
List<Widget> _buildPageIndicator() {
List<Widget> list = [];
for (int i = 0; i < _numPages; i++) {
list.add(i == _currentPage ? _indicator(true) : _indicator(false));
}
return list;
}
Widget _indicator(bool isActive) {
return AnimatedContainer(
duration: Duration(milliseconds: 150),
margin: EdgeInsets.symmetric(horizontal: 8.0),
height: 8.0,
width: isActive ? 24.0 : 16.0,
decoration: BoxDecoration(
color: isActive ? Colors.white : Color(0xFF7B51D3),
borderRadius: BorderRadius.all(Radius.circular(12)),
),
);
}
@override
Widget build(BuildContext context) {
return Scaffold(
body: AnnotatedRegion<SystemUiOverlayStyle>(
value: SystemUiOverlayStyle.light,
child: Container(
decoration: BoxDecoration(
gradient: LinearGradient(
begin: Alignment.topCenter,
end: Alignment.bottomCenter,
stops: [0.1, 0.4, 0.7, 0.9],
colors: [
Color(0xFF3594DD),
Color(0xFF4563DB),
Color(0xFF5036D5),
Color(0xFF5B16D0),
],
),
),
child: Padding(
padding: EdgeInsets.symmetric(vertical: 40.0),
child: Column(
crossAxisAlignment: CrossAxisAlignment.stretch,
children: <Widget>[
Container(
alignment: Alignment.centerRight,
child: FlatButton(
onPressed: () => print('Skip'),
child: Text(
'Skip',
style: TextStyle(
color: Colors.white,
fontSize: 20.0,
),
),
),
),
Container(
height: 600.0,
child: PageView(
physics: ClampingScrollPhysics(),
controller: _pageController,
onPageChanged: (int page) {
setState(() {
_currentPage = page;
});
},
children: <Widget>[
Padding(
padding: EdgeInsets.all(40.0),
child: Column(
crossAxisAlignment: CrossAxisAlignment.start,
children: <Widget>[
Center(
child: Image(
image: AssetImage(
'assets/images/lorem_Ipsum.png',
),
height: 300.0,
width: 300.0,
),
),
SizedBox(height: 30.0),
Text(
'Welcome to ...',
//style: kTitleStyle,
),
SizedBox(height: 15.0),
Text(
'lorem Ipsum',
//style: kSubtitleStyle,
),
],
),
),
Padding(
padding: EdgeInsets.all(40.0),
child: Column(
crossAxisAlignment: CrossAxisAlignment.start,
children: <Widget>[
Center(
child: Image(
image: AssetImage(
'assets/images/lorem_Ipsum.png',
),
height: 300.0,
width: 300.0,
),
),
SizedBox(height: 30.0),
Text(
'lorem Ipsum',
//style: kTitleStyle,
),
SizedBox(height: 15.0),
Text(
'lorem Ipsum',
//style: kSubtitleStyle,
),
],
),
),
Padding(
padding: EdgeInsets.all(40.0),
child: Column(
crossAxisAlignment: CrossAxisAlignment.start,
children: <Widget>[
Center(
child: Image(
image: AssetImage(
'assets/images/lorem_Ipsum.png',
),
height: 300.0,
width: 300.0,
),
),
SizedBox(height: 30.0),
Text(
'lorem Ipsum',
//style: kTitleStyle,
),
SizedBox(height: 15.0),
Text(
'lorem Ipsum',
//style: kSubtitleStyle,
),
],
),
),
],
),
),
Row(
mainAxisAlignment: MainAxisAlignment.center,
children: _buildPageIndicator(),
),
_currentPage != _numPages - 1
? Expanded(
child: Align(
alignment: FractionalOffset.bottomRight,
child: FlatButton(
onPressed: () {
_pageController.nextPage(
duration: Duration(milliseconds: 500),
curve: Curves.ease,
);
},
child: Row(
mainAxisAlignment: MainAxisAlignment.center,
mainAxisSize: MainAxisSize.min,
children: <Widget>[
Text(
'Next',
style: TextStyle(
color: Colors.white,
fontSize: 22.0,
),
),
SizedBox(width: 10.0),
Icon(
Icons.arrow_forward,
color: Colors.white,
size: 30.0,
),
],
),
),
),
)
: Text(''),
],
),
),
),
),
bottomSheet: _currentPage == _numPages - 1
? Container(
height: 50.0,
width: double.infinity,
color: Colors.white,
child: GestureDetector(
onTap: () => print('Get Started'),
child: Center(
child: Padding(
padding: EdgeInsets.only(bottom: 5.0),
child: Text(
'Get Started',
style: TextStyle(
color: Color(0xFF5B16D0),
fontSize: 20.0,
fontWeight: FontWeight.bold,
),
),
),
),
),
)
: Text(''),
);
}
}
这篇关于Flutter入门画面只有一次的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
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