SharedPreferences value needs to be reset every other time - flutter

Question

So,in this included flutter code,I am using a if loop in checkFirstSeen() to set my seen boolean to a value. This will then set my SharedPreferences value for the app. However,on every other restart of the application,I have to press the GotoHomepage button as opposed to it working automatically based off of the SharedPreferences value that was set. How can I fix this?
import 'dart:async';
import 'package:flutter/material.dart';
import 'package:shared_preferences/shared_preferences.dart';
import 'package:audiotest/UI/homepage.dart';
void main() => runApp(new MaterialApp(
title: "TestAudio",
initialRoute: '/intro_route',
routes: {
'/intro_route': (context) => IntroScreen(),
'/homescreen_route': (context) => MainPersistentTabBar2(),
}));
class IntroScreen extends StatefulWidget {
#override
IntroScreenstate2 createState() => IntroScreenstate2();
}
class IntroScreenstate2 extends State<IntroScreen> {
bool buttonstatus = true;
Future checkFirstSeen() async {
SharedPreferences prefs = await SharedPreferences.getInstance();
bool seen = (prefs.getBool('seen') ?? false);
prefs.setBool('seen', false);
if (buttonstatus == false) {
prefs.setBool('seen', true);
}
if (seen == true) {
Navigator.pushNamed(context, '/homescreen_route');
} else {
}
}
#override
void initState() {
super.initState();
new Timer(new Duration(milliseconds: 1), () {
checkFirstSeen();
});
}
#override
Widget build(BuildContext context) {
return new Scaffold(
body: new Center(
child: new Column(
mainAxisSize: MainAxisSize.min,
children: <Widget>[
new Text('This is the placeholder for the TOS'),
new MaterialButton(
child: new Text('Go to Home Page'),
onPressed: () {
buttonstatus = false;
checkFirstSeen();
//Navigator.pushNamed(context, '/homescreen_route');
},
)
],
),
),
);
}
}

Answer 1

You can copy paste run full code below
You can get seen in main() and check seen directly in initialRoute
code snippet
bool seen;
Future<void> main() async {
WidgetsFlutterBinding.ensureInitialized();
SharedPreferences prefs = await SharedPreferences.getInstance();
seen = await prefs.getBool("seen");
await prefs.setBool("seen", true);
runApp(MyApp());
}
class MyApp extends StatelessWidget {
#override
Widget build(BuildContext context) {
return MaterialApp(
...
initialRoute:
seen == false || seen == null ? "/intro_route" : "/homescreen_route",
routes: {
'/homescreen_route': (context) => MainPersistentTabBar2(
title: "demo",
),
"/intro_route": (context) => IntroScreen(),
},
);
}
}
working demo
full code
import 'package:flutter/material.dart';
import 'package:shared_preferences/shared_preferences.dart';
import 'package:flutter/services.dart';
bool seen;
Future<void> main() async {
WidgetsFlutterBinding.ensureInitialized();
SharedPreferences prefs = await SharedPreferences.getInstance();
seen = await prefs.getBool("seen");
await prefs.setBool("seen", true);
runApp(MyApp());
}
class MyApp extends StatelessWidget {
#override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
primarySwatch: Colors.blue,
),
initialRoute:
seen == false || seen == null ? "/intro_route" : "/homescreen_route",
routes: {
'/homescreen_route': (context) => MainPersistentTabBar2(),
"/intro_route": (context) => IntroScreen(),
},
);
}
}
class MainPersistentTabBar2 extends StatefulWidget {
#override
MainPersistentTabBarState2 createState() => MainPersistentTabBarState2();
}
class MainPersistentTabBarState2 extends State<MainPersistentTabBar2> {
Brightness brightness;
#override
Widget build(BuildContext context) {
return new MaterialApp(
theme: new ThemeData(
primarySwatch: Colors.blue,
brightness: Brightness.dark,
),
home: DefaultTabController(
length: 4,
child: Scaffold(
appBar: AppBar(
bottom: TabBar(
isScrollable: true,
tabs: <Widget>[
Container(
width: 90,
height: 40,
alignment: Alignment.center,
child: Text("Session 1"),
),
Container(
width: 90,
height: 40,
alignment: Alignment.center,
child: Text("Session 2"),
),
Container(
width: 90,
height: 40,
alignment: Alignment.center,
child: Text("Session 3"),
),
Container(
width: 90,
height: 40,
alignment: Alignment.center,
child: Text("Session 4"),
),
],
),
title: Text('Own The Tone '),
/*actions: <Widget>[
PopupMenuButton<String>(
onSelected: _choiceAction,
itemBuilder: (BuildContext context) {
return Constants.choices.map((String choice) {
return PopupMenuItem<String>(
value: choice,
child: Text(choice),
);
}).toList();
},
)
],*/
),
body: TabBarView(
children: <Widget>[
FirstScreen(),
Center(child: Text("Sample two")),
Center(child: Text("Sample three")),
Center(child: Text("Sample four")),
],
),
),
),
);
}
// This area controls the settings menus
/* void _choiceAction(String choice) {
if (choice == Constants.about) {
Navigator.of(context).push(new MaterialPageRoute(builder: (context) {
return new Scaffold(
appBar: new AppBar(
title: new Text('About the app'),
),
body: new PageView(),
);
}));
} else if (choice == Constants.settings) {
Navigator.of(context).push(new MaterialPageRoute(builder: (context) {
return new Scaffold(
appBar: new AppBar(
title: new Text('Settings'),
),
body: new Container(
child: Center(
child: Text('placeholder'),
)),
);
}));
}
}*/
}
class FirstScreen extends StatefulWidget {
#override
_FirstScreenState createState() => _FirstScreenState();
}
class _FirstScreenState extends State<FirstScreen> {
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text("First Screen"),
),
body: Text("First"));
}
}
class IntroScreen extends StatefulWidget {
#override
_IntroScreenState createState() => _IntroScreenState();
}
class _IntroScreenState extends State<IntroScreen> {
#override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(
title: Text("Introduction"),
),
body: Text("Intro"));
}
}