mutableStateOf 在视图模型中更新，但在 @Compose 中没有效果

Question

我的 HiltViewModel 中有一个 mutableStateof，名为“loading”。我正在更新从视图模型中的函数加载的值，该值被传递给 @composable 函数并在那里使用。情况是加载值在 viewModel 中完美更新，但没有反映在 @Composable 函数中。我的视图模型是：

@HiltViewModel
class AuthenticationViewModel @Inject constructor(
    private val repository: AppRepository,
    application: Application
): ViewModel() {
   val loading = mutableStateOf(false)

   fun update() = viewModelScope.launch {
      loading.value = true
   }
}

加载值已在此处更新，但未反映在 @composable 中

@Composable
fun LoginScreen(
    viewModel: AuthenticationViewModel,
    actions: MainActions
) {
    val loading = viewModel.loading.value

    //Loading is another composable function where bool value is passed
    Loading(state = loading)
    CustomNavigationButton(title = "Sign In",enabled = true,onClick = 
    {viewModel.update()})
}

现在，当我单击导航按钮时，将调用视图模型函数，并且加载状态也会更新，但不会反映在 @Composable 中

加载可组合项是：

@Composable
fun Loading(state:Boolean) {
    var showDialog by remember { mutableStateOf(state) }

    if(showDialog){
        Dialog(onDismissRequest = { showDialog = false }, DialogProperties(
            dismissOnBackPress = false,dismissOnClickOutside = false
        )) {
            Box(
                modifier = Modifier.size(100.dp).background(Color.White, shape = RoundedCornerShape(8.dp)),
                contentAlignment= Alignment.Center,
            ){
                CircularProgressIndicator()
            }
        }
    }
}

Answer 1

问题出在 Loader 可组合函数中。if 条件始终设置为 false，因为可变状态在该特定可组合函数中永远不会更新。替换：

@Composable
fun Loading(state:Boolean) {
    var showDialog by remember { mutableStateOf(state) }

    if(showDialog){
        Dialog(onDismissRequest = { showDialog = false }, DialogProperties(
            dismissOnBackPress = false,dismissOnClickOutside = false
        )) {
            Box(
                modifier = Modifier.size(100.dp).background(Color.White, shape = RoundedCornerShape(8.dp)),
                contentAlignment= Alignment.Center,
            ){
                CircularProgressIndicator()
            }
        }
    }
}

和

@Composable
fun Loading(state:Boolean) {
    if(state){
        Dialog(onDismissRequest = {}, DialogProperties(
            dismissOnBackPress = false,dismissOnClickOutside = false
        )) {
            Box(
                modifier = Modifier.size(100.dp).background(Color.White, shape = RoundedCornerShape(8.dp)),
                contentAlignment= Alignment.Center,
            ){
                CircularProgressIndicator()
            }
        }
    }
}