Manage authentification state with fireabse and flutter

Question

I tried to implements this Authentification Firebase with Porvider here the issue is I want to save the state of variable loggedIn even I close and reponning the app so I used this code but dont work

    class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Consumer<AuthenticationService>(builder: (_, auth, __) {
      if (auth.getCurrentUser() != null)
        return HomeView();
      else
        return TermsView();
    });
  }
}

here method to get current user

Future getCurrentUser() async {
FirebaseUser _user ;
_user = await FirebaseAuth.instance.currentUser();

return _user ;
}

I get always true any help please