ViewModel

Koin provides multiplatform ViewModel support through the koin-core-viewmodel module. This allows you to declare and inject AndroidX ViewModel instances across all Kotlin Multiplatform targets.

Setup

Add the core ViewModel dependency:

// build.gradle.kts (commonMain)
implementation("io.insert-koin:koin-core-viewmodel:$koin_version")

For platform-specific injection APIs, add:

// Android
implementation("io.insert-koin:koin-android:$koin_version")

// Compose Multiplatform
implementation("io.insert-koin:koin-compose-viewmodel:$koin_version")

Declaring ViewModels

Compiler Plugin DSL

class UserViewModel(
    private val repository: UserRepository
) : ViewModel()

val appModule = module {
    viewModel<UserViewModel>()
}

Annotations

@KoinViewModel
class UserViewModel(
    private val repository: UserRepository
) : ViewModel()

Classic DSL

val appModule = module {
    // With constructor reference
    viewModelOf(::UserViewModel)

    // With lambda
    viewModel { UserViewModel(get()) }
}

ViewModel with Parameters

Pass parameters at injection time using @InjectedParam:

Compiler Plugin DSL

class DetailViewModel(
    @InjectedParam val itemId: String,
    private val repository: DetailRepository
) : ViewModel()

val appModule = module {
    viewModel<DetailViewModel>()
}

Annotations

@KoinViewModel
class DetailViewModel(
    @InjectedParam val itemId: String,
    private val repository: DetailRepository
) : ViewModel()

Classic DSL

val appModule = module {
    viewModel { params ->
        DetailViewModel(
            itemId = params.get(),
            repository = get()
        )
    }
}

ViewModel Scope

ViewModels that need their own scoped dependencies use the viewModelScope archetype. Dependencies declared inside viewModelScope are tied to the ViewModel's lifecycle.

Compiler Plugin DSL

val appModule = module {
    viewModelScope {
        scoped<UserCache>()
        scoped<UserRepository>()
        viewModel<UserViewModel>()
    }
}

Annotations

@ViewModelScope
class UserCache

@ViewModelScope
class UserRepository(private val cache: UserCache)

@KoinViewModel
@ViewModelScope
class UserViewModel(
    private val repository: UserRepository
) : ViewModel()

Classic DSL

val appModule = module {
    viewModelScope {
        scoped { UserCache() }
        scoped { UserRepository(get()) }
        viewModel { UserViewModel(get()) }
    }
}

info

Dependencies inside viewModelScope are created when the ViewModel is first accessed and destroyed when the ViewModel is cleared.

Injecting ViewModels

In Compose (Multiplatform)

Use koinViewModel() in Composable functions:

@Composable
fun UserScreen() {
    val viewModel = koinViewModel<UserViewModel>()
    // or with parameters
    val detailVM = koinViewModel<DetailViewModel> { parametersOf("item_123") }
}

In Android

Use by viewModel() delegate in Activity or Fragment:

class UserActivity : AppCompatActivity() {
    private val viewModel: UserViewModel by viewModel()

    // With parameters
    private val detailVM: DetailViewModel by viewModel { parametersOf("item_123") }
}

SavedStateHandle

Add SavedStateHandle to your ViewModel constructor - Koin injects it automatically:

@KoinViewModel
class MyViewModel(
    private val handle: SavedStateHandle,
    private val repository: UserRepository
) : ViewModel() {

    val userId: String? = handle["userId"]
}

val appModule = module {
    viewModel<MyViewModel>()  // Compiler Plugin DSL
    // or
    viewModelOf(::MyViewModel)  // Classic DSL
}

Quick Reference

Approach	Module Declaration	Scope Declaration
Compiler Plugin DSL	viewModel<MyVM>()	viewModelScope { viewModel<MyVM>() }
Annotations	@KoinViewModel	@KoinViewModel @ViewModelScope
Classic DSL	viewModelOf(::MyVM)	viewModelScope { viewModelOf(::MyVM) }

Platform	Injection API
Compose	koinViewModel<MyVM>()
Android	by viewModel()

Platform-Specific Features

• Android: See Android ViewModel for Activity/Fragment sharing, Navigation Graph scoping
• Compose: See Compose ViewModel for Compose-specific APIs

Next Steps

• Scopes - Core scope concepts
• Android ViewModel - Android-specific features
• Compose - Compose Multiplatform integration