Skip to main content
Version: 4.1

Koin for Jetpack Compose and Compose Multiplatform

This page describe how you can inject your dependencies for your Android Jetpack Compose or your Multiplaform Compose apps.

Koin Compose Multiplatform vs Koin Android Jetpack Compose​

Since mid-2024, Compose applications can be done with the Koin Multiplatform API. All APIs are identical between Koin Jetpack Compose (koin-androidx-compose) and Koin Compose Multiplatform (koin-compose).

What Koin package for Compose?​

For a pure Android app that uses only the Android Jetpack Compose API, use the following packages:

  • koin-androidx-compose - to unlock Compose base API + Compose ViewModel API
  • koin-androidx-compose-navigation - Compose ViewModel API with Navigation API integration

For an Android/Multiplatform app, use the following packages:

  • koin-compose - Compose base API
  • koin-compose-viewmodel - Compose ViewModel API
  • koin-compose-viewmodel-navigation - Compose ViewModel API with Navigation API integration

Starting over an existing Koin context​

By using the startKoin function previous to your Compose application, your application is ready to welcome Koin injection. Nothing is required anymore to setup your Koin context with Compose.

note

KoinContext and KoinAndroidContext are deprecated

Starting Koin with a Compose App - KoinApplication​

If you don't have access to a space where you can run the startKoin function, you can relay on Compose and Koin to start your Koin configuration.

The compose function KoinApplication helps to create a Koin application instance, as a Composable:

@Composable
fun App() {
    KoinApplication(application = {
        modules(...)
    }) {
        
        // your screens here ...
        MyScreen()
    }
}

The KoinApplication function will handle the start and stop of your Koin context, regarding the cycle of the Compose context. This function starts and stops a new Koin application context.

info

In an Android Application, the KoinApplication will handle any need to stop/restart Koin context regarding configuration changes or drop of Activities.

note

(Experimental API) You can use the KoinMultiplatformApplication to replace a multiplatform entry point: it's the same as KoinApplication but injects automatically androidContext and androidLogger for you.

Compose Preview with KoinApplicationPreview​

The KoinApplicationPreview compose function is dedicated to preview a Composable:

@Preview(name = "1 - Pixel 2 XL", device = Devices.PIXEL_2_XL, locale = "en")
@Preview(name = "2 - Pixel 5", device = Devices.PIXEL_5, locale = "en", uiMode = Configuration.UI_MODE_NIGHT_YES)
@Preview(name = "3 - Pixel 7 ", device = Devices.PIXEL_7, locale = "ru", uiMode = Configuration.UI_MODE_NIGHT_YES)
@Composable
fun previewVMComposable(){
    KoinApplicationPreview(application = { modules(appModule) }) {
        ViewModelComposable()
    }
}

Injecting into a @Composable​

While writing your composable function, you gain access to the following Koin API: koinInject(), to inject instance from Koin container

For a module that declares a 'MyService' component:

val androidModule = module {
    single { MyService() }
    // or constructor DSL
    singleOf(::MyService)
}

We can get your instance like that:

@Composable
fun App() {
    val myService = koinInject<MyService>()
}

To keep aligned on the functional aspect of Jetpack Compose, the best writing approach is to inject instances directly into functions parameters. This way allow to have default implementation with Koin, but keep open to inject instances how you want.

@Composable
fun App(myService: MyService = koinInject()) {

}

Injecting into a @Composable with Parameters​

While you request a new dependency from Koin, you may need to inject parameters. To do this you can use parameters parameter of the koinInject function, with the parametersOf() function like this:

@Composable
fun App() {
    val myService = koinInject<MyService>(parameters = parametersOf("a_string"))
}
info

You can use parameters with lambda injection like koinInject<MyService>{ parametersOf("a_string") }, but this can have a performance impact if your recomposing a lot around. This version with lambda needs to unwrap your parameters on call, to help avoid remembering your parameters.

From version 4.0.2 of Koin, koinInject(Qualifier,Scope,ParametersHolder) is introduced to let you use parameters in the most efficient way

ViewModel for @Composable​

The same way you have access to classical single/factory instances, you gain access to the following Koin ViewModel API:

  • koinViewModel() - inject ViewModel instance
  • koinNavViewModel() - inject ViewModel instance + Navigation arguments data (if you are using Navigation API)

For a module that declares a 'MyViewModel' component:

module {
    viewModel { MyViewModel() }
    // or constructor DSL
    viewModelOf(::MyViewModel)
}

We can get your instance like that:

@Composable
fun App() {
    val vm = koinViewModel<MyViewModel>()
}

We can get your instance in the function parameters:

@Composable
fun App(vm : MyViewModel = koinViewModel()) {

}
note

Lazy API are not supported with updates of Jetpack Compose

Shared Activity ViewModel (4.1 - Android)​

You can now use the koinActivityViewModel() to inject a ViewModel from the same ViewModel host: Activity.

@Composable
fun App() {
    // hold ViewModel instance at Activity level
    val vm = koinActivityViewModel<MyViewModel>()
}

ViewModel and SavedStateHandle for @Composable​

You can have a SavedStateHandle constructor parameter, which will be injected regarding the Compose environment (Navigation BackStack or ViewModel). Either it's injected via ViewModel CreationExtras or via Navigation BackStackEntry:

// Setting objectId argument in Navhost
NavHost(
    navController,
    startDestination = "list"
) {
    composable("list") { backStackEntry ->
        //...
    }
    composable("detail/{objectId}") { backStackEntry ->
        val objectId = backStackEntry.arguments?.getString("objectId")?.toInt()
        DetailScreen(navController, objectId!!)
    }
}

// Injected Argument in ViewModel
class DetailViewModel(
    private val savedStateHandle: SavedStateHandle
) : ViewModel() {

    init {
        println("$this - objectId: ${savedStateHandle.get<String>("objectId")}")
    }
}
note

More details about SavedStateHandle injection difference: https://github.com/InsertKoinIO/koin/issues/1935#issuecomment-2362335705

Shared ViewModel and Navigation (Experimental)​

Koin Compose Naviation has now a NavBackEntry.sharedKoinViewModel() function, to allow to retrieve ViewModel already stored in current NavBackEntry. Inside your navigation part, just use sharedKoinViewModel:

navigation<Route.BookGraph>(
                startDestination = Route.BookList
            ) {
                composable<Route.BookList>(
                    exitTransition = { slideOutHorizontally() },
                    popEnterTransition = { slideInHorizontally() }
                ) {
                    // Use SharedViewModel here ...

                    val selectedBookViewModel =
                        it.sharedKoinViewModel<SelectedBookViewModel>(navController)

Module loading & unloading tied to Composable​

Koin offers you a way to load specific modules for a given Composable function. The rememberKoinModules function load Koin modules and remember on current Composable:

@Composable
@Preview
fun MyComponentComposable() {
    // load module at first call of this component
    rememberKoinModules(myModule)
}

You can use one of the abandon function, to unload module on 2 aspects:

  • onForgotten - after a composition is dropped out
  • onAbandoned - composition has failed

For this use unloadOnForgotten or unloadOnAbandoned argument for rememberKoinModules.

Creating Koin Scope with Composable​

The composable function rememberKoinScope and KoinScope allow to handle Koin Scope in a Composable, follow-up current to close scope once Composable is ended.

info

this API is still unstable for now