Synthetics to Viewbinding issues (onBackPress & Navigation Drawer) - kotlin

Question

I am updating my app to completely remove synthetics and move to viewbinding, however I am struggling with converting the onBackPressed method (now also deprecated) with my Activity, Fragment and Navigation Drawer.
I originally had it like this:
Activity (Before)
override fun onCreate(savedInstanceState: Bundle?) {
Log.d(TAG, "onCreate")
super.onCreate(savedInstanceState)
val activityBinding: BusinessActivityBinding = DataBindingUtil.setContentView(
this,
R.layout.business_activity
)
nav_view.setNavigationItemSelectedListener(this)
val headerView = activityBinding.navView.getHeaderView(0)
headerView.navHeaderEmailText.setOnClickListener { sendSupportEmail() }
navController = findNavController(this, R.id.NavHostFragment)
// other stuff
}
fun openCloseNavigationDrawer() {
if (business_drawer_layout.isDrawerOpen(GravityCompat.START)) {
business_drawer_layout.closeDrawer(GravityCompat.START)
} else {
business_drawer_layout.openDrawer(GravityCompat.START)
}
}
override fun onBackPressed() {
val navHostFragment: NavHostFragment = supportFragmentManager.findFragmentById(R.id.NavHostFragment) as NavHostFragment
val backStackEntryCount = navHostFragment?.childFragmentManager?.backStackEntryCount
when {
(business_drawer_layout.isDrawerOpen(GravityCompat.START)) -> business_drawer_layout.closeDrawer(
GravityCompat.START
)
(backStackEntryCount == 0) -> dialogLeaveApp()
else -> super.onBackPressed()
}
}
private fun dialogLeaveApp(){
MaterialDialog(this).show {
title(R.string.business_activity_dialog_leave_app_heading)
message(R.string.business_activity_dialog_leave_app_message)
positiveButton(R.string.business_activity_dialog_confirm_button){
super.onBackPressed()
}
negativeButton(R.string.business_activity_dialog_cancel_button) {
dismiss()
}
}
override fun onNavigationItemSelected(item: MenuItem): Boolean {
when (item.itemId) {
R.id.nav_sites_fragment -> navigateWithClearStack(R.id.sitesFragment)
R.id.nav_projects_fragment -> navigateWithClearStack(R.id.projectsFragment)
R.id.nav_contacts_fragment -> navigateWithClearStack(R.id.contactsFragment)
R.id.nav_tasks_fragment -> navigateWithClearStack(R.id.tasksFragment)
R.id.nav_profile_fragment -> makeToast("Todo: Profile Fragment")
R.id.nav_settings_fragment -> navigateWithClearStack(R.id.settingsFragment)
}
business_drawer_layout.closeDrawer(GravityCompat.START)
return true
}
private fun navigateWithClearStack(destination: Int) {
businessViewModel.clearCurrentVMData()
val navHostFragment: NavHostFragment = supportFragmentManager.findFragmentById(R.id.NavHostFragment) as NavHostFragment
val inflater = navHostFragment.navController.navInflater
val graph = inflater.inflate(R.navigation.business_navigation)
graph.startDestination = destination
navController.graph = graph
}
}
Fragment (already using viewbinding)
class SitesFragment : Fragment() {
private lateinit var navController: NavController
private lateinit var businessViewModel: BusinessViewModel
private lateinit var sitesAdapter: SitesRecyclerViewAdapter
private var _binding: SitesFragmentBinding? = null // this property is only valid between onCreateView & onDestroyView
private val binding get() = _binding!! //https://stackoverflow.com/questions/57647751/android-databinding-is-leaking-memory
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View {
Log.d(TAG, "onCreateView()")
activity?.let {
businessViewModel = ViewModelProvider(it).get(BusinessViewModel::class.java)
Log.d(TAG, "businessViewModel = $businessViewModel")
}
Log.d(TAG, businessViewModel.currentStatus("${TAG}, onCreateView()"))
// Inflate the layout for this fragment
_binding = SitesFragmentBinding.inflate(inflater, container, false)
val view = binding.root
binding.apply {
sitesDrawerMenuButton.setOnClickListener {
(activity as BusinessActivity).openCloseNavigationDrawer()
Log.d(TAG, "sitesDrawerMenuButton clicked, openCloseNavigationDrawer()")
}
// Other listeners
}
return view
}
Activity (After)
private var _binding: BusinessActivityBinding? = null
private val binding get() = _binding!!
override fun onCreate(savedInstanceState: Bundle?) {
Log.d(TAG, "onCreate")
super.onCreate(savedInstanceState)
// Inflate the layout for this activity
_binding = BusinessActivityBinding.inflate(layoutInflater)
setContentView(binding.root)
val navHostFragment = supportFragmentManager.findFragmentById(R.id.NavHostFragment) as NavHostFragment
this.navController = navHostFragment.navController
binding.navView.setupWithNavController(this.navController)
// Setup OnBackPressedDispatcher
val backPressedCallback = object:OnBackPressedCallback(false){
override fun handleOnBackPressed() {
onBackButtonPressed()
}
}
// Other stuff
}
fun openCloseNavigationDrawer() { // accessed by Fragment
if (binding.businessDrawerLayout.isDrawerOpen(GravityCompat.START)) {
binding.businessDrawerLayout.closeDrawer(GravityCompat.START)
} else {
binding.businessDrawerLayout.openDrawer(GravityCompat.START)
}
}
fun onBackButtonPressed() {
val navHostFragment: NavHostFragment = supportFragmentManager.findFragmentById(R.id.NavHostFragment) as NavHostFragment
val backStackEntryCount = navHostFragment.childFragmentManager.backStackEntryCount
when {
(binding.businessDrawerLayout.isDrawerOpen(GravityCompat.START)) -> binding.businessDrawerLayout.closeDrawer(
GravityCompat.START
)
(backStackEntryCount == 0) -> dialogLeaveApp()
}
}
private fun dialogLeaveApp(){
// as before
}
override fun onNavigationItemSelected(item: MenuItem): Boolean {
// as before
}
private fun navigateWithClearStack(destination: Int) {
// as before
}
So the issue is that when you back press, it simply exits the app, rather than triggering my function onBackButtonPressed() (which replaces the depricated onBackPressed())and variable 'backPressedCallback' is never used..