iOS action handling not always working with Firebase calls

[kostapostolakis]

I have the NewGameViewModel in commonMain Shared code of KMM.

interface NewGameIntents {
    fun updateUserName(userName: String)
    fun startNewGameButtonTapped()
    fun newGameCreated(newGameID: String)
    fun newGameCreationFailed()
}

sealed interface NewGameActions {
    data class CreateNewGameAction(val userName: String): NewGameActions
    data class GoToMainScreenAction(val gameID: String, val userName: String) : NewGameActions
}

class NewGameViewModel: BaseViewModel(), NewGameIntents {
    private val _actions = Channel<NewGameActions>()
    val actions: CFlow<NewGameActions> get() = _actions.receiveAsFlow().cFlow()

    private val _userName: CMutableStateFlow<String> = MutableStateFlow("").cMutableStateFlow()
    val userName: CStateFlow<String> = _userName.cStateFlow()

    init {
        val previousName = SettingsHelper().lastGameName ?: SettingsHelper().userName
        previousName?.let {
            updateUserName(it)
        }
    }

    override fun updateUserName(userName: String) {
        _userName.value = userName
    }

    override fun startNewGameButtonTapped() {
        updateUserName(_userName.value.trim())
        createNewGame()
    }

    override fun newGameCreated(newGameID: String) {
        showLoading(false)
        viewModelScope.launch {
            _actions.send(NewGameActions.GoToMainScreenAction(newGameID, _userName.value))
        }
    }

    override fun newGameCreationFailed() {
        showLoading(false)
        showErrorAlert()
    }

    private fun createNewGame() {
        showLoading(true)
        viewModelScope.launch {
            _actions.send(NewGameActions.CreateNewGameAction(_userName.value))
        }
    }
}

I have also the NewGameScreen in iOS:

struct NewGameScreen: View {
    
    @ObservedObject var newGameViewModel: NewGameViewModel = NewGameViewModel()
    
    var body: some View {        
        ScrollView {
            VStack(spacing: 0) {
                CustomTextField(
                    value: newGameViewModel.state(\.userName),
                    label: getKmmString(stringResource: \.your_name),
                    onTextChange: { text in
                        newGameViewModel.updateUserName(userName: text)
                    }
                )
                
                Spacer().frame(height: 32)
                CustomButton(
                    text: getKmmString(stringResource: \.start_game),
                    onClick: {
                        newGameViewModel.startNewGameButtonTapped()
                    }
                )
            }
            .padding(16)
        }
        .navigationBarBackButtonHidden(true)
        .onReceive(createPublisher(newGameViewModel.actions)) { action in
            handleNewGameAction(action: action)
        }
    }
    
    private func handleNewGameAction(action: NewGameActions) {
        switch action {
        case let action as NewGameActionsCreateNewGameAction: do {
            let newGameMap = getMapFromFunction(name: action.userName) // Create map here
            
            var documentReference: DocumentReference? = nil
            documentReference = Firestore.firestore()
                .collection(Game.companion.COLLECTION_GAMES)
                .addDocument(data: newGameMap) { error in
                    if let error {
                        newGameViewModel.doNewGameCreationFailed()
                    } else if let documentId = documentReference?.documentID, !documentId.isEmpty {
                        newGameViewModel.doNewGameCreated(newGameID: documentId)
                    } else {
                        newGameViewModel.doNewGameCreationFailed()
                    }
                }
        }
            
        case let action as NewGameActionsGoToMainScreenAction: do {
            closeScreen()
            PalermoHelper().goToMainGameScreen(gameID: action.gameID, name: action.userName)
        }
            
        default: return
        }
    }
}

When I tap the button, startNewGameButtonTapped() function of viewModel is called and then the action CreateNewGameAction should be handled by iOS.

Sometimes it works and sometimes not. Maybe it is a lifecycle issue, but I am not sure and I do not know how to solve it. Do you have any ideas?

[alobaili]

I'm also having the same issue, for some reason on some screens, onReceive with createPublisher does not correctly receive the emitted value and the block is not triggered even through the value is correctly emitted from the shared module.

[kostapostolakis]

Do we have any solution on this?

[Alex009]

maybe publisher disposed before receive event, but cancellation of Flow subscription done in async way, so we have small period when Flow still active and receive event, but Publisher already cancelled and can't receive new events.

moko-mvvm/mvvm-flow/apple/xcode/mokoMvvmFlowSwiftUI/CFlowExt.swift

Line 44 in ad0f844

DispatchQueue.main.async {

try to change code to:

    func cancel() {
            self.disposable.dispose()
    }

[kostapostolakis]

It seems that is working. I test all the flows and I will inform you. Regarding Android, it has the same problem. I should call GlobalScope.launch instead of viewModelScope.launch to play correctly. Do you have any suggestions here?

[kostapostolakis]

iOS is not playing when I make a Firebase call and onSuccess I make another one directly. Any thoughts?

[kostapostolakis]

I have something like this in ViewModel:

viewModelScope.launch {
      _profileActions.send(ProfileActions.GetUserDetails)
      _profileActions.send(ProfileActions.GetUserStatistics)
}

In every action, I make a call in Firebase, but the first call is not made.

If I change viewModelScope -> GlobalScope, it plays correctly!