(Jetpack Compose) -> 加载 State 无法正常工作

Question

我试图显示一个加载微调器，但加载 state 总是在撰写 function 时显示错误值。

我创建了一个自定义微调器，但它没有显示

@Composable
private fun MainContent(viewModel: SearchJourneyViewModel = hiltViewModel()) {
    val state = viewModel.state
    
    Loader(isDialogVisible = state.isLoading)
}

在 viewModel 加载 state 正在刷新并返回我需要的值：

@HiltViewModel
class SearchJourneyViewModel @Inject constructor(
    private val cityRepository: CityListRepository,
) : ViewModel() {

    var state by mutableStateOf(SearchJourneyState().mock())
        private set

    init {
        loadCityList()
    }

 private fun loadCityList() {
        viewModelScope.launch {
            cityRepository
                .getCityList()
                .collect { result ->
                    when (result) {
                        is Resource.Success -> {
                            state = 
                                state.copy(
                                    fromCity = //result,
                                    toCity = //result,
                                    isLoading = false,
                                    error = null
                                )
                            } 
                        }

                        is Resource.Error -> {
                            state = 
                                state.copy(
                                    fromCity = null,
                                    toCity = null,
                                    isLoading = false,
                                    error = result.message
                            )
                        }

                        is Resource.Loading -> {
                            state =
                                state.copy(isLoading = result.isLoading)
                        }
                    }
                }
        }
    }
}

这是我的 state：

data class SearchJourneyState(
    val cityList: List<City>? = null,
    val isLoading: Boolean = false,
    val isCityLoading: Boolean = false,
) 

Answer 1

主要问题似乎是您收集 state 的方式。

尝试将其定义为StateFlow ：

val viewStateFlow: StateFlow<VS> = MutableStateFlow()

然后简单地将它收集到你的 UI 层：

val viewState by viewModel.viewStateFlow.collectAsState()

然后你应该能够在 UI 中加载更改:)