Swift interop¶

`kmp-viewmodel` and `Swift` interoperability¶

kmp-viewmodel can be exported and used in Swift as usual, however there are few limitations.

Exposing `kmp-viewmodel` sources to Swift¶

KotlinX Coroutines Flow are Kotlin interfaces with generic types. Since generics for interfaces are not exported to Swift, kmp-viewmodel provides Flow wrapper classes.

You can wrap Flows sources using corresponding wrap() extension functions:

Flow<T: Any>.wrap(): NonNullFlowWrapper<T>
Flow<T>.wrap(): NullableFlowWrapper<T>
StateFlow<T: Any>.wrap(): NonNullStateFlowWrapper<T>
StateFlow<T>.wrap(): NullableStateFlowWrapper<T>

Example:

// Kotlin code
class SharedViewModel : ViewModel() {
  private val _state = MutableStateFlow(State())
  val stateFlow: NonNullStateFlowWrapper<State> = _state.wrap()
}

Using wrappers in Swift¶

Flow wrappers can be used in Swift as usual:

// Swift code
func foo() {
  let viewModel = SharedViewModel()

  val closable = viewModel.stateFlow.subscribe(
    scope: viewModel.viewModelScope,
    onValue: { state in
      // do something with state
    }
  )

  // At some point later
  closable.close()
}

If Kotlin Code does not wrap Flows to FlowWrappers, we can also wrap them in Swift code.

// Swift code
let nonNull = NonNullFlowWrapperKt.wrap(self) as! NonNullFlowWrapper<T>
let nullable = NullableFlowWrapperKt.wrap(self) as! NullableFlowWrapper<T>
...

Combine interop¶

Please check kotlinxCoroutinesFlowExtensions.swift .

RxSwift interop¶

Please check kotlinxCoroutinesFlow+RxSwift.swift.