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DI (Dependency Injection)

The project uses Koin for Dependency Injection. The Koin modules (dataModule, domainModule, presentationModule, and the appModules aggregate) are defined in the root/Di.kt file. The root/AppInitializer bootstrap loads them at startup via startKoin { modules(appModules) }.

Koin APIs you'll use​

These are the Koin APIs you reach for when registering dependencies in KMPStarterKit:

  • single — registers a singleton: one shared instance for the whole app.
  • factory — creates a new instance every time it's injected.
  • singleOf / factoryOf — the constructor-reference DSL form of single / factory (e.g. singleOf(::UserRepository)).
  • bind — binds the instance to an interface or superclass. Example: singleOf(::UserPreferencesImpl) bind UserPreferences::class.
  • viewModelOf — registers a ViewModel in the presentation module. Example: viewModelOf(::HomeViewModel).

Example of DI Setup​

In this project, the DI setup includes multiple modules:

  • Domain Module: Used for core business logic.

  • Data Module: Handles application data like repositories, preferences, and API services.

    • Singletons: ApplicationScope, UserRepository, UserPreferences.
    • Factories: For objects like ApiService and BackgroundExecutor.

  • Presentation Module: Handles UI-related objects like ViewModels for different screens. ViewModels are registered using viewModelOf(), for example: viewModelOf(::OnBoardingViewModel), viewModelOf(::ProfileViewModel), viewModelOf(::PaywallViewModel).

Platform-Specific DI​

The project uses Kotlin's expect and actual to define platform-specific dependencies. The platformModule is expected on different platforms (iOS, Android) and injected accordingly (see util/Platform.kt). This allows platform-specific implementations to be handled easily. For more information about achieving platform-specific DI with Koin in Kotlin Multiplatform, check out this article: Achieving Platform-Specific Implementations with Koin.

For more information on using Koin, refer to Koin Documentation.