alexandrade00's questions

Tentei seguir os exemplos na documentação do Android, mas não consigo implementar a navegação usando Navigation Compose, ViewModel e Hilt. Nenhum erro é lançado e no NavigationScreen LaunchedEffect não é acionado em emissões do ViewModel.

Compostos:

@HiltAndroidApp
class MyApplication : Application() {}

@Serializable
object NavScreen

@AndroidEntryPoint
class MainActivity : ComponentActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        enableEdgeToEdge()
        setContent {
            val navController = rememberNavController()

            PhotosSyncTheme {
                NavHost(
                    navController = navController,
                    startDestination = NavScreen
                ) {
                    composable<NavScreen> { NavigationScreen(navController) }
                    composable<NavigationEvent.NavigateToHome> { HomeScreen() }
                    composable<NavigationEvent.NavigateToSettings> { Settings() }
                }
            }
        }
    }
}

@Composable
fun NavigationScreen(navController: NavController) {
    val navViewModel = hiltViewModel<NavigationViewModel>()

    val navigationEvent by navViewModel.navigationEvents.collectAsState(initial = NavigationEvent.NavigateToHome)

    LaunchedEffect(navigationEvent) {
        Log.d("Navigation Screen", navigationEvent.toString())
        navigationEvent.let { event ->
            Log.d("Navigation Screen", event.toString())
            when (event) {
                is NavigationEvent.NavigateBack -> navController.popBackStack()
                NavigationEvent.NavigateToHome -> navController.navigate(NavigationEvent.NavigateToHome)
                NavigationEvent.NavigateToSettings -> navController.navigate(NavigationEvent.NavigateToSettings)
            }
        }
    }
}

@OptIn(ExperimentalMaterial3Api::class)
@Composable
fun HomeScreen() {
    val navViewModel = hiltViewModel<NavigationViewModel>()
    var selectedItem by remember { mutableIntStateOf(0) }

    Scaffold(
        modifier = Modifier.fillMaxSize(),
        topBar = {
            TopAppBar(title = { Text("Photos Sync") }, actions = {
                IconButton(onClick = {
                    navViewModel.navigateToSettings()
                }) {
                    Icon(
                        imageVector = Icons.Filled.Settings,
                        contentDescription = "Settings icon"
                    )
                }
            })
        }
    )
    { }
}

@OptIn(ExperimentalMaterial3Api::class)
@Composable
fun Settings() {
    val viewModel = hiltViewModel<NavigationViewModel>()

    Scaffold(
        modifier = Modifier.fillMaxSize(),
        topBar = {
            TopAppBarWithBack(title = "Definições")
        }
    )
    { }
}

Modelo de exibição:

@HiltViewModel
class NavigationViewModel @Inject constructor() : ViewModel() {
    private val _navigationEvents = MutableSharedFlow<NavigationEvent>()
    val navigationEvents: SharedFlow<NavigationEvent> = _navigationEvents.asSharedFlow()

    fun navigateBack() {
        viewModelScope.launch { _navigationEvents.emit(NavigationEvent.NavigateBack) }
    }

    fun navigateToHome() {
        viewModelScope.launch { _navigationEvents.emit(NavigationEvent.NavigateToHome) }
    }

    fun navigateToSettings() {
        viewModelScope.launch {
            Log.d("Navigation ViewModel", "Emit Navigate To Settings")
            try {
                _navigationEvents.emit(NavigationEvent.NavigateToSettings)

            } catch (e: Exception) {
                Log.e("Navigation ViewModel", "Error emitting navigation event")
            } finally {
                Log.d("Navigation ViewModel", "done Emit Navigate To Settings")
            }
        }
    }

    fun navigateTo(event: NavigationEvent) {
        viewModelScope.launch { _navigationEvents.emit(event) }
    }

    sealed class NavigationEvent {
        @Serializable
        object NavigateBack : NavigationEvent()

        @Serializable
        object NavigateToHome : NavigationEvent()

        @Serializable
        object NavigateToSettings : NavigationEvent()
    }
}

Eu esperava que quando eu clicasse no botão de configurações, o composable de configurações fosse empurrado para o topo da pilha de composables usandonavController.navigate