Common ViewModel

Adding the common ViewModel to your project

To use the multiplatform ViewModel implementation, add the following dependency to your commonMain source set:

kotlin {
    // ...
    sourceSets {
        // ...
        commonMain.dependencies {
            // ...
            implementation("org.jetbrains.androidx.lifecycle:lifecycle-viewmodel-compose:2.8.2")
        }
        // ...
    }
}

Using ViewModel in common code

Compose Multiplatform implements the common ViewModelStoreOwner interface, so in general using the ViewModel class in common code is not much different from Android best practices.

Using the navigation example:

1. Declare the ViewModel class:

import androidx.lifecycle.ViewModel
import androidx.lifecycle.viewmodel.compose.viewModel

class OrderViewModel : ViewModel() {
   private val _uiState = MutableStateFlow(OrderUiState(pickupOptions = pickupOptions()))
   val uiState: StateFlow<OrderUiState> = _uiState.asStateFlow()
   // ...
}

2. Add the ViewModel to your composable function:

@Composable
fun CupcakeApp(
   viewModel: OrderViewModel = viewModel { OrderViewModel() },
) {
   // ...
}

tip

When running coroutines in a ViewModel, remember that the ViewModel.viewModelScope value is tied to the Dispatchers.Main.immediate value, which might be unavailable on desktop by default. To make ViewModel coroutines work correctly with Compose Multiplatform, add the kotlinx-coroutines-swing dependency to your project. See the Dispatchers.Main documentation for details.

On non-JVM platforms, objects cannot be instantiated using type reflection. So in common code you cannot call the viewModel() function without parameters: every time a ViewModel instance is created, you need to provide at least an initializer as an argument.

If only an initializer is provided, the library creates a default factory under the hood. But you can implement your own factories and call more explicit versions of the common viewModel(...) function, just like with Jetpack Compose.