如何收听导航组件中的片段更改? [英] How to listen to Fragment Change in Navigation Component?

问题描述

如何在新的导航组件中添加片段更改侦听器?

How can I add Fragment Change Listener in new Navigation Component?

我有一个BottomNavigationView，其中在官方示例之后使用了新的导航组件

I have a BottomNavigationView in which I used new Navigation Component following official sample

我的 BottomNavigationView 中有四个目的地，所有目的地都有其导航图.

I have four destinations in my BottomNavigationView, all of them have their navigation graphs.

val navGraphIds = listOf(R.navigation.nav_home, R.navigation.nav_discover, R.navigation.nav_search, R.navigation.nav_my)

val controller = bottom_nav.setupWithNavController(
    navGraphIds = navGraphIds,
    fragmentManager = supportFragmentManager,
    containerId = R.id.navHostContainer,
    intent = intent
)

controller.observe(this, Observer { navController ->
    setupActionBarWithNavController(navController)
})

当片段在4个导航图中的任何一个发生变化时，我都想在我的 MainActivity 中有一个侦听器.

I want to have a listener in my MainActivity when fragment changed in any of 4 navigation graphs.

控制器 仅在在 BottomNavigationView 目标之间切换时才有效.

the controller is only affective when switching between BottomNavigationView destinations.

推荐答案

您是否尝试过 NavController.OnDestinationChangedListener ?

private lateinit var controller: NavController // don't forget to initialize

private val listener = NavController.OnDestinationChangedListener { controller, destination, arguments ->
    // react on change
    // you can check destination.id or destination.label and act based on that
}

override fun onResume() {
    super.onResume()
    controller.addOnDestinationChangedListener(listener)
}

override fun onPause() {
    controller.removeOnDestinationChangedListener(listener)
    super.onPause()
}

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