My flutter app logs out after hot restart,Cannot make app stay logged in even after restart - flutter

Question

i implemented login after onboard screen and logged in but unfortunately each time i restart my app i am brought back to the welcome page.i also want to implement a splash screen but don't know how to add it in the MyApp material root widget since i have returned the introduction/on boarding page and set the welcome page to come after it.I also want to find a way to check auth state after one time introduction/on boarding screen. I'll appreciate
int initScreen;
Future<void> main() async {
WidgetsFlutterBinding.ensureInitialized();
await Firebase.initializeApp();
//on Board Screen Intialization
SharedPreferences prefs = await SharedPreferences.getInstance();
initScreen = prefs.getInt('initScreen');
await prefs.setInt("initScreen", 1);
runApp(MyApp());
}
class MyApp extends StatelessWidget {
// This widget is the root of your application.
#override
Widget build(BuildContext context) {
return MaterialApp(
debugShowCheckedModeBanner: false,
home: Introduction(),
initialRoute: initScreen == 0 || initScreen == null ? 'onboard' : 'home',
routes: {
'home': (context) => WelcomeScreen(),
'onboard': (context) => Introduction()
},
);
}
}
class Login extends StatefulWidget {
const Body({Key key}) : super(key: key);
#override
_LoginState createState() => _LoginState();
}
class _LoginState extends State<Login> {
TextEditingController _email = TextEditingController();
TextEditingController _password = TextEditingController();
isLoading = false;
#override
Widget build(BuildContext context) {
Size size = MediaQuery.of(context).size;
return Scaffold(
body: Background(
child: isLoading == false
? SingleChildScrollView(
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: <Widget>[
Text(
"LOGIN",
style: TextStyle(
fontWeight: FontWeight.bold, fontSize: 20),
),
SizedBox(height: size.height * 0.03),
SvgPicture.asset(
"assets/icons/login.svg",
height: size.height * 0.35,
),
SizedBox(height: size.height * 0.03),
TextFieldContainer(
child: TextFormField(
controller: _email,
cursorColor: kPrimaryColor,
decoration: InputDecoration(
icon: Icon(
Icons.email,
color: kPrimaryColor,
),
hintText: "Email",
border: InputBorder.none,
),
),
),
TextFieldContainer(
child: TextFormField(
controller: _password,
obscureText: true,
cursorColor: kPrimaryColor,
decoration: InputDecoration(
hintText: "Password",
icon: Icon(
Icons.lock,
color: kPrimaryColor,
),
suffixIcon: Icon(
Icons.visibility,
color: kPrimaryColor,
),
border: InputBorder.none,
),
),
),
RoundedButton(
text: "LOGIN",
press: () {
setState(() {
isLoading = true;
});
AuthClass()
.SignIn(
_email.text.trim(), _password.text.trim())
.then((value) {
if (value == 'Welcome') {
setState(() {
isLoading = false;
});
Navigator.pushAndRemoveUntil(
context,
MaterialPageRoute(
builder: (context) => Home()),
(route) => false);
} else {
setState(() {
isLoading = false;
});
ScaffoldMessenger.of(context).showSnackBar(
SnackBar(content: Text(value)));
}
});
},
),
SizedBox(height: size.height * 0.03),
AlreadyHaveAnAccountCheck(
press: () {
Navigator.push(
context,
MaterialPageRoute(
builder: (context) {
return SignUpScreen();
},
),
);
},
),
],
),
)
: Center(
child: CircularProgressIndicator(),
)));
}
}
class AuthClass {
FirebaseAuth _auth = FirebaseAuth.instance;
//Create account
Future<String> createAcount(String email, String password) async {
try {
await _auth.createUserWithEmailAndPassword(
email: email, password: password);
return "Account Successifuly Created";
} on FirebaseAuthException catch (e) {
if (e.code == 'weak-password') {
return 'The password provided is too weak.';
} else if (e.code == 'email-already-in-use') {
return 'The account already exists for that email';
}
} catch (e) {
return 'Error ocurred';
}
}
//SignIn User
Future<String> SignIn(String email, String password) async {
try {
await _auth.signInWithEmailAndPassword(email: email, password: password);
return 'Welcome';
} on FirebaseAuthException catch (e) {
if (e.code == 'user-not-found') {
return 'No user found for that email.';
} else if (e.code == 'wrong-password') {
return 'Wrong password provided for that user.';
}
}}
//ResetPAssword
//SignOut
void signOut() {
_auth.signOut();
}
//try
Future<String> Reset(
String email,
) async {
try {
await _auth.sendPasswordResetEmail(
email: email,
);
return 'Email sent';
} catch (e) {
return 'Error Occured';
}
}
}

Answer 1

You need a "pre-login" screen, I usually call it Loading anyway, and on that screen I just bring a Circular Progress, just to give feedback to the user who is loading something.
Meanwhile, in initState, call a validate user method, where you check if you have any users logged in (of course, you should store this in SQLite, Shared Preferences or something like that). Depending on the return, you redirect to Login or to your Home.