Future main() async {
      WidgetsFlutterBinding.ensureInitialized();
      SharedPreferences prefs = await SharedPreferences.getInstance();
      var email = prefs.getString('email');
      print(email);
      runApp(MaterialApp(home: email == null ? Login() : Home()));
    }
    
 //Save the required user details after the successful login

class Login extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        child: RaisedButton(
          onPressed: () async {
            //after the login REST api call && response code ==200
            SharedPreferences prefs = await SharedPreferences.getInstance();
            prefs.setString('email', 'useremail@gmail.com');
            Navigator.pushReplacement(context,
                MaterialPageRoute(builder: (BuildContext ctx) => Home()));
          },
          child: Text('Login'),
        ),
      ),
    );
  }
}
//clear the details on logout

class Home extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Home'),
      ),
      body: Center(
        child: RaisedButton(
          onPressed: () async {
            SharedPreferences prefs = await SharedPreferences.getInstance();
            prefs.remove('email');
            Navigator.pushReplacement(context,
                MaterialPageRoute(builder: (BuildContext ctx) => Login()));
          },
          child: Text('Logout'),
        ),
      ),
    );
  }
}