Has anyone figured out a nice way to bridge a

State

from

StateFlow<State>

to SwiftUi as

@ObservedObject

? Rather than doing

@Published var state: State = State.companion.DEFAULT

viewModel.onState { (state) in
  self.state = state
}

Just use this plugin: https://github.com/rickclephas/KMP-NativeCoroutines

@xxfast following more recent article talks about using that KMP-NativeCoroutines library https://johnoreilly.dev/posts/kmp-native-coroutines/

Some useful operators for Swift: • https://developer.apple.com/documentation/combine/publisher/assertnofailure(_:file:line:) • https://developer.apple.com/documentation/combine/publisher/assign(to:) I would probably go with something like:

@Published var state: State = viewModel.stateNativeValue

createPublisher(for: viewModel.stateNative).assertNoFailure().assign(to: &$state)

Maybe it’s event possible to create a custom property wrapper of it (haven’t tried that yet).

loving kmp-native-coroutines, the plugin does makes things easier. Though i should say i've been running into this exception getting thrown (im using the

-new-mm

variant

Uncaught Kotlin exception: kotlin.native.IncorrectDereferenceException: Trying to access top level value not marked as @ThreadLocal or @SharedImmutable from non-main thread

I'll post this one as a seperate thread i think

You have enabled use of new memory model?

I derped - forgot to enable this aaand its working 🙌 thanks guys

Just use 1.7.20-Beta, it is enabled by default 😄

Hi all, (again). Just wanted to share my approach in sharing state from a common ViewModel with kmp-native-coroutines. My viewmodel is defined

// commonMain
class LoginViewModel(..) : ViewModel() {
  private val stateFlow: MutableStateFlow<LoginState> = MutableStateFlow(defaultState)

  val states: StateFlow<LoginState> = stateFlow.asStateFlow()
}

on ios, i have

class LoginViewModelDelegate: ObservableObject {

  @Published var state: LoginLoginState = LoginLoginState.companion.DEFAULT
  
  private let viewModel: LoginLoginViewModel = AppModule.LoginModule().viewModel

  private var stateCollection: Task<Void, Error>? = nil

  func collect() {
    stateCollection = Task {
      let states = asyncStream(for: viewModel.statesNative)
      for try await _state in states {
        self.state = _state
      }
    }
  }

  func cancel() {
    stateCollection?.cancel()
  }
}

and the swiftUi view looks like

struct LoginScreen: View {
  @StateObject private var viewModelDelegate = LoginViewModelDelegate()

  var body: some View {
    LoginView(
      state: viewModelDelegate.state,
      onChange: { state in
        viewModelDelegate.onChange(state: state)
      },
      onSubmit: { state in
        viewModelDelegate.onSubmit(state: state)
      }
    )
    .onAppear(perform: viewModelDelegate.collect)
    .onDisappear(perform: viewModelDelegate.cancel)
  }
}

This works, but i dont like it 🤔 Is there a way to avoid having two "ViewModel"s ( view model and the delegate) here?

Technically you can. Using property wrappers. Here is a POC https://gist.github.com/rickclephas/4c2ab99add21688001168886f759fa50 Though it has a major limitation, you can't access instance members in the propery wrapper constructor. But maybe that isn't needed if you can somehow wrap the StateObject as well.

check this post - i implement viewmodel binding without swift observableobject wrapper

Alternative you can use the closure initialer for parameter based StateObject:

struct Login: View {
    init(viewModel: @autoclosure @escaping () -> LoginViewModel) {
        self._viewModel = StateObject(wrappedValue: viewModel())
    }

    @StateObject var viewModel: LoginViewModel

    @State private var error: Failure? = nil
    @State private var disableLogin = true

    var body: some View {
        Form {
            TextField("Username", text: viewModel.binding(\.userName))
            SecureField("Password", text: viewModel.binding(\.password))

And custom bindings to map a flow to Swift.Binding: https://github.com/hfhbd/ComposeTodo/blob/main/iosApp/Shared/ViewModel.swift Based on @alex009

@xxfast one minor comment about code above.....could you use

.task

view modifier in SwiftUI to call

viewModelDelegate.collect

(which becomes

async

function)....with automatic cancellation then when view disappears (so shouldn't need I think

cancel

?

Yeah I saw that, xcode told me that it is not supported for my min iOS target 🤔

but you were still able to use

for await

? Perhaps some differences in iOS versions for those

Let me check the exact error again

task

requires iOS15.....I think that was originally case for async/await but I believe that at least got back ported to earlier version.....

Ah, that explains it

what iOS version are you targetting?

14, need to support n-1 :(

ok, so maybe when iOS 16 comes out soon you can start using iOS 15 stuff 🙂

task

requires iOS15.....I think that was originally case for async/await but I believe that at least got back ported to earlier version.....

Yeah if I am not mistaken only Swift concurrency has been back ported to iOS 13, SwiftUI and Combine async APIs haven’t.

It's a pity....the combination of 2 is pretty compelling