What is the purpose of authentication state unknown in flutter_bloc? - flutter

Question

I was going through flutter_bloc documentation https://bloclibrary.dev/#/flutterlogintutorial, I saw that AuthenticationState has 3 states
enum AuthenticationStatus { authenticated, unauthenticated, unknown }
I couldn't understand the purpose of unknown state.
Here is the full code
bloc state
enum AuthenticationStatus { authenticated, unauthenticated, unknown }
class AuthenticationState extends Equatable {
const AuthenticationState._({
this.status = AuthenticationStatus.unknown,
this.user = User.empty,
});
const AuthenticationState.unknown() : this._();
const AuthenticationState.authenticated(User user)
: this._(status: AuthenticationStatus.authenticated, user: user);
const AuthenticationState.unauthenticated()
: this._(status: AuthenticationStatus.unauthenticated, user: User.empty);
final AuthenticationStatus status;
final User user;
#override
List<Object> get props => [status, user];
}
bloc_implementation
class AuthenticationBloc
extends Bloc<AuthenticationEvent, AuthenticationState> {
AuthenticationBloc({
#required AuthenticationRepository authenticationRepository,
}) : assert(authenticationRepository != null),
_authenticationRepository = authenticationRepository,
super(const AuthenticationState.unknown()) {
_userSubscription = _authenticationRepository.userStream.listen(
(user) => add(AuthenticationUserChanged(user)),
);
}
final AuthenticationRepository _authenticationRepository;
StreamSubscription<User> _userSubscription;
#override
Stream<AuthenticationState> mapEventToState(
AuthenticationEvent event,
) async* {
if (event is AuthenticationUserChanged) {
yield _mapAuthenticationUserChangedToState(event);
} else if (event is AuthenticationLogoutRequested) {
unawaited(_authenticationRepository.logOut());
}
}
#override
Future<void> close() {
_userSubscription?.cancel();
return super.close();
}
AuthenticationState _mapAuthenticationUserChangedToState(
AuthenticationUserChanged event,
) =>
event.user != User.empty
? AuthenticationState.authenticated(event.user)
: const AuthenticationState.unauthenticated();
}
UI
import 'package:authentication_repository/authentication_repository.dart';
import 'package:flutter/material.dart';
import 'package:flutter_bloc/flutter_bloc.dart';
import 'package:flutter_login/authentication/authentication.dart';
import 'package:flutter_login/home/home.dart';
// import 'package:flutter_login/login/login.dart';
import 'package:flutter_login/splash/splash.dart';
import 'package:flutter_login/splash/view/spash_page.dart';
import 'package:user_repository/user_repository.dart';
import 'authentication/bloc/authentication_bloc.dart';
import 'home/view/home_page.dart';
import 'login/view/login_page.dart';
class App extends StatelessWidget {
const App({
Key? key,
required this.authenticationRepository,
required this.userRepository,
}) : super(key: key);
final AuthenticationRepository authenticationRepository;
final UserRepository userRepository;
#override
Widget build(BuildContext context) {
return RepositoryProvider.value(
value: authenticationRepository,
child: BlocProvider(
create: (_) => AuthenticationBloc(
authenticationRepository: authenticationRepository,
userRepository: userRepository,
),
child: AppView(),
),
);
}
}
class AppView extends StatefulWidget {
#override
_AppViewState createState() => _AppViewState();
}
class _AppViewState extends State<AppView> {
final _navigatorKey = GlobalKey<NavigatorState>();
NavigatorState get _navigator => _navigatorKey.currentState!;
#override
Widget build(BuildContext context) {
return MaterialApp(
navigatorKey: _navigatorKey,
builder: (context, child) {
return BlocListener<AuthenticationBloc, AuthenticationState>(
listener: (context, state) {
switch (state.status) {
case AuthenticationStatus.authenticated:
_navigator.pushAndRemoveUntil<void>(
HomePage.route(),
(route) => false,
);
break;
case AuthenticationStatus.unauthenticated:
_navigator.pushAndRemoveUntil<void>(
LoginPage.route(),
(route) => false,
);
break;
default:
break;
}
},
child: child,
);
},
onGenerateRoute: (_) => SplashPage.route(),
);
}
}
I think it is to display a splash screen, but we need to edit android and ios native code to display splash screen right?
Please help me to understand its purpose.