Android Jetpack Navigation, BottomNavigationView with Youtube or Instagram like proper back navigation (fragment back stack)?

Question

Android Jetpack Navigation, BottomNavigationView with auto fragment back stack on back button click?

What I wanted, after choosing multiple tabs one after another by

Answer 1

Originally answered here: https://stackoverflow.com/a/63645978/8956093

In Jetpack Navigation Componenet, if you want to perform some operation when fragment is poped then you need to override following functions.

1. Add OnBackPressedCallback in fragment to run your special operation when back is pressed present in system navigation bar at bottom.

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
   
        onBackPressedCallback = object : OnBackPressedCallback(true) {
            override fun handleOnBackPressed() {
                //perform your operation and call navigateUp
               findNavController().navigateUp()
            }
        }
    requireActivity().onBackPressedDispatcher.addCallback(onBackPressedCallback)
    }
   

2. Add onOptionsItemMenu in fragment to handle back arrow press present at top left corner within the app.

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)
   
        setHasOptionsMenu(true)
    }
   
   override fun onOptionsItemSelected(item: MenuItem): Boolean {
      if (item.itemId == android.R.id.home) {
          //perform your operation and call navigateUp
          findNavController().navigateUp()
          return true
      }
      return super.onOptionsItemSelected(item)
   }
   

3. If there is no special code to be run when back is pressed on host fragment then use onSupportNavigateUp in Activity.

    override fun onSupportNavigateUp(): Boolean {
      if (navController.navigateUp() == false){
        //navigateUp() returns false if there are no more fragments to pop
        onBackPressed()
      }
      return navController.navigateUp()
    }
   

Note that onSupportNavigateUp() is not called if the fragment contains onOptionsItemSelected()