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Presentation Package

The Presentation package holds the app's user interface.

presentation/
├── components/    reusable composables (toolbar, dialogs, ads, credit, premium)
├── navigation/    Routes.kt, NavigationState.kt, Navigator.kt, AppNavigation.kt
└── screens/       one folder per screen (home, gallery, account, paywall, onboarding, …)

The app's visual style — colors, typography, and light/dark themes — lives separately in the designsystem module, so it can be reused across modules.

components​

Reusable UI elements like the toolbar, loading indicators, and dialogs that keep the design consistent across the app.

Every navigation destination, the back-stack model, the Navigator API, and the root AppNavigation composable. Feature folders intentionally contain no navigation glue — see the dedicated Navigation page for the full picture.

screens​

Every screen in the app. Each screen folder follows the same structure:

  • Screen — the main composable for the UI.
  • UiState — the current state of the screen; it also defines UiEvent, the user actions the screen handles.
  • ViewModel — manages the screen's state. Extends ViewModel from androidx.lifecycle, reads UiState, and handles the UiEvents triggered by the user.

The route definitions and the wiring that connects each screen to the navigator (push targets, back behaviour, parameter passing) live in presentation/navigation/Routes.kt and AppNavigation.kt, not in the feature folder.

For new screens, extend the ViewModel class from androidx.lifecycle. When you need to call a suspend function, launch it within viewModelScope.

class NewViewModel() : ViewModel() {
    fun testFunction() = viewModelScope.launch {
        //Call suspend function
    }
}

To obtain a ViewModel instance inside the entry<…> block in AppNavigation.kt, use Koin's koinViewModel helper:

entry<OnBoardingScreenRoute> {
    val viewModel = koinViewModel<OnBoardingViewModel>()
    OnBoardingScreen(viewModel = viewModel, /* … */)
}

The Navigation 3 entry decorator scopes ViewModels to their NavEntry, so each viewModel lives as long as its destination is on the back stack and is cleared automatically when popped — no separate "navigator-scoped" helper needed.

Ensure that the DI setup is done in root/Di.kt within the presentationModule, for example, by adding viewModelOf(::NewViewModel) to handle dependencies for the new ViewModel.