android-kmp-viewmodel

name	android-kmp-viewmodel
description	Sharing ViewModel logic across Android and iOS in KMP — CommonViewModel base, StateFlow in shared code, platform wrappers for iOS consumption. Use when building shared presentation logic, moving ViewModel to commonMain, or exposing Flow to Swift. Trigger on: "shared ViewModel", "KMP ViewModel", "commonMain ViewModel", "StateFlow iOS", "KMP presentation".

KMP ViewModel

Strategy

Keep ViewModel class on Android (it owns viewModelScope). Move all state logic to a platform-agnostic Presenter or CommonViewModel in commonMain that takes an explicit CoroutineScope.

CommonViewModel (commonMain)

// commonMain — core:domain or feature module
abstract class CommonViewModel {
    private val viewModelScope = CoroutineScope(SupervisorJob() + Dispatchers.Main)

    protected fun launch(block: suspend CoroutineScope.() -> Unit): Job =
        viewModelScope.launch(block = block)

    open fun onCleared() {
        viewModelScope.cancel()
    }
}

Android ViewModel wraps it

// androidMain
class TaskListViewModel(
    private val getTasks: GetTasksUseCase,
) : ViewModel() {

    private val _state = MutableStateFlow(TaskListState())
    val state: StateFlow<TaskListState> = _state.asStateFlow()

    init {
        viewModelScope.launch {
            getTasks().collect { tasks ->
                _state.update { it.copy(tasks = tasks) }
            }
        }
    }
}

iOS Swift wrapper (StateFlow → Combine)

// iosMain — thin wrapper so Swift can observe
class TaskListIosViewModel(
    private val getTasks: GetTasksUseCase,
) : CommonViewModel() {

    private val _state = MutableStateFlow(TaskListState())
    val state: StateFlow<TaskListState> = _state.asStateFlow()

    init {
        launch {
            getTasks().collect { tasks ->
                _state.update { it.copy(tasks = tasks) }
            }
        }
    }
}

// Swift — consume the StateFlow via a helper
let vm = TaskListIosViewModel(getTasks: ...)
let publisher = vm.state.toPublisher() // use KMP-NativeCoroutines or manual wrapper

Recommended library

KMP-NativeCoroutines generates Swift async/await wrappers for StateFlow and Flow automatically.

// commonMain
import com.rickclephas.kmp.nativecoroutines.NativeCoroutinesState

abstract class CommonViewModel {
    @NativeCoroutinesState
    abstract val state: StateFlow<*>
}

Checklist

• CommonViewModel in commonMain, no Android imports
• Android ViewModel delegates to shared logic or shares StateFlow
• iOS wrapper calls onCleared() in deinit
• No LiveData in shared code — StateFlow only
• Use KMP-NativeCoroutines or equivalent for Swift consumption