Performance with injectable, get_it Flutter

I have a question. In my project, I have some class with singleton.

• DioMethod (some api configs),
• Repository (Connect ApiProvider and BLoc class),
• ApiProvider (call api => get data => pass to Repository),
• Some BloC classes such as MoviesBloc, MovieDetailBloc,..i created a BLoC class for each Screen.

and init all at $initGetIt the same.

_i1.GetIt $initGetIt(_i1.GetIt get,
    {String? environment, _i2.EnvironmentFilter? environmentFilter}) {
  final gh = _i2.GetItHelper(get, environment, environmentFilter);
  gh.singleton<_i3.DioConfig>(_i3.DioConfig());
  gh.singleton<_i4.DioMethod>(_i4.DioMethod(get<_i3.DioConfig>()));
  gh.singleton<_i5.MovieApiProvider>(
      _i5.MovieApiProvider(get<_i4.DioMethod>()));
  gh.singleton<_i6.Repository>(_i6.Repository());
  gh.lazySingleton<_i7.MovieDetailBloc>(
      () => _i7.MovieDetailBloc(get<_i6.Repository>()),
      dispose: (i) => i.dispose());
  gh.lazySingleton<_i8.MoviesBloc>(() => _i8.MoviesBloc(get<_i6.Repository>()),
      dispose: (i) => i.dispose());
  return get;
}

I think If I scale my project, I can get some problem.

1. This function will be too large and we have too much singleton still live in app.
2. We need to init a lot of Object when opening the app => Can delay app?
3. How to create a singleton only alive when access to the screen and destroyed after pop this screen.

Thank you for your anwser!

This function will be too large and we have too much singleton still live in app.

I have hundreds of GetIt singletons and I do not see any problems.

We need to init a lot of Object when opening the app => Can delay app?

If you are worried about number of Objects - do not need to worry. When Flutter builds a frame (you know, it builds 60 frames per second), it creates a huge widget tree contains thousands of widgets and each widget contains dozens of objects. So hundreds of objects are really a very small number. Dart's Garbage Collector is designed for the many-object case.

How to create a singleton only alive when access to the screen and destroyed after pop this screen.

class MyPageOne extends StatefulWidget {
  const MyPageOne({Key? key}) : super(key: key);

  @override
  _MyPageOneState createState() => _MyPageOneState();
}

class _MyPageOneState extends State<MyPageOne> {
  @override
  void initState() {
    super.initState();
    GetIt.I.registerSingleton<MyClass>(MyClass());
  }
  
  @override
  void dispose() {
    GetIt.I.unregister<MyClass>();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return ...your page...;
  }
}

This is just an example and you can, for example, encapsulate it into a widget.