Custom "navigate up" behavior for certain fragment using Navigation component

Question

I want to add custom up navigation from fragment using Navigation component

In my build.gradle(app) I use androidx.appcompat:appcompat:1.1.0-alpha04 dependency to have access to onBackPressedDispatcher from activity.

So I implemented OnBackPressedCallback in my fragment and registered callback to dispatcher:

requireActivity().onBackPressedDispatcher.addCallback(this)

I expected that pressing navigate up in toolbar will call it, but it doesn't. Pressing device's back button calls it as expected.

Is there a similar way to add some callback in fragment on navigate up action?

UPDATE

overridden methods onOptionsItemSelected and onSupportNavigateUp doesn't invoked on pressing up button in toolbar

Answer 1

I found a solution

handleOnBackPressed() method invokes only on device's back button click. I wonder, why neither onOptionsItemSelected() nor onSupportNavigateUp() methods haven't been called on pressing "up button" in toolbar. And the answer is I used

NavigationUI.setupWithNavController(toolbar, navController, appBarConfiguration)

in activity to setup toolbar with navigation component. And that made toolbar responsive for work with navigation internally, pressing "up button" haven't invoked any of overridden methods in activity or fragments.

Instead should be used

NavigationUI.setupActionBarWithNavController(this, navController, appBarConfiguration)

That will make actionBar responsive for navigation, thus I can use overridden functions onOptionsItemSelected() and onSupportNavigateUp() And best place (in my case) to add custom behavior on "up button" click for certain screen is

onSupportNavigateUp()

of hosted activity, like that

override fun onSupportNavigateUp(): Boolean {
        val navController = this.findNavController(R.id.mainNavHostFragment)
        return when(navController.currentDestination?.id) {
            R.id.destinationOfInterest -> {
                // custom behavior here 
                true
            }
            else -> navController.navigateUp()
        }
}

But worth to say, that if you want implement custom behavior directly in fragment, answer of @Enzokie should work like a charm