flutter_codex_storage_01.dart

// Logged status.

bool isLogged = false;

// Firebase authentication instance.

FirebaseAuth _auth = FirebaseAuth.instance;

// The init state will check the logged status of the user.

@override
void initState() {
  super.initState();
  _auth.currentUser().then((response) {
    if (response != null) {
      setState(() {
        isLogged = true;
      });
    }
  });
}

// The login button will login to the app using
// the user credentials, and sets the logged status
// to true.

RaisedButton(
  child: Text(
    'Login',
  ),
  color: Colors.blue[400],
  onPressed: () async {
    await _auth.signInWithEmailAndPassword(
      email: '[email protected]',
      password: 'password',
    );
    setState(() {
      isLogged = true;
    });
  }
),