如何检查当前目的地是否是 Jetpack Compose 类型安全导航中的顶级？

Question

我有一个多后堆栈导航图，其中底部导航的每个起始节点都是顶层。

如何检查我当前是否位于顶级目的地，以便调整 UI 元素的显示？

以下代码示例无法解决问题：

val isTopLevel = navController.previousBackStackEntry == null

在顶级目的地之间，我按如下方式导航：

navController.navigate(destination.route) {
    popUpTo(navController.graph.findStartDestination().id) {
        saveState = true
        inclusive = true
    }
    launchSingleTop = true
    restoreState = true
}

Answer 1

一个技巧是定义您的顶级目的地。例如：

@Composable
fun MyScreen(navController: NavController) {
    val topLevelDestinations = listOf("home", "profile", "settings") // Replace with your actual route names

    val currentDestination = navController.currentBackStackEntryAsState().value?.destination
    val isTopLevelDestination = currentDestination?.route in topLevelDestinations

    // Use isTopLevelDestination to modify your UI
    if (isTopLevelDestination) {
        // Your UI for top-level destination
        Text(text = "You are in a top-level destination")
    } else {
        // Your UI for non-top-level destination
        Text(text = "You are in a nested destination")
    }
}