custom back button - Android Navigation

Issue

I have a form and want to get a confirmation message from the user before the user leaves it.

i want provide custom back button when user touch this button:

i try this:

val onBackPressedCallback = object : OnBackPressedCallback(true) {
            override fun handleOnBackPressed() {
            }
        }
requireActivity().onBackPressedDispatcher.addCallback(this,onBackPressedCallback)

but only seems to work for providing custom back behavior to the built-in software/hardware back button and not the back arrow button

How can I do this?

Solution

Use onSupportNavigateUp, and replace yourCurrentFragmentID to your current fragment id. All these should be done in MainActivity.

 navController = findNavController(R.id.nav_host_fragment)

 setupActionBarWithNavController(navController!!)

 override fun onSupportNavigateUp(): Boolean {
        return when(navController?.currentDestination?.id) {
            R.id.yourCurrentFragmentID -> {
                showDialog()
                true
            }
            else -> navController?.navigateUp()!!
        }
    }

Edit

If your fragment already use onOptionsItemSelected, you can handle the logic by checking itemId.

 override fun onOptionsItemSelected(item: MenuItem): Boolean {
        val id = item.itemId
        if (id == R.id.save) {
           // your save button code logic 
        }else if(id ==android.R.id.home){ 
            // display confirmation message
        }
        return super.onOptionsItemSelected(item)
    }

Answered By - John Joe