CODEWITHSUNDEEP
androidkotlinandroid-architecture-navigation
M. Akar
M. Akar

Reputation: 1865

How to persist navigating component destination after minimizing the app

I have an app with 3 main destinations which can be accessed by a bottom nav view. Each destination has its own navigation graph.

The problem is that when I minimize and reopen my app, the navigation components reset to the default destination. Why does this happen?

My main activity: (Irrelevant code omitted)

class MainActivity : AppCompatActivity() {

    // List of base host containers
    val fragments = listOf(
            HomeHostFragment(),
            CoursesHostFragment(),
            SearchHostFragment()
    )

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        val viewPager: ViewPager = findViewById(R.id.main_activity_pager)
        viewPager.adapter = ViewPagerAdapter()
    }

    inner class ViewPagerAdapter : FragmentPagerAdapter(supportFragmentManager) {
        override fun getItem(position: Int): Fragment =
                fragments[position]

        override fun getCount(): Int =
                fragments.size
    }
}

HomeHostFragment.kt:

class HomeHostFragment : Fragment() {
    private lateinit var navController: NavController

    override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View? =
            inflater.inflate(R.layout.fragment_home_host, container, false)

    override fun onStart() {
        super.onStart()
        navController = requireActivity().findNavController(R.id.nav_host_home)
        navController.setGraph(R.navigation.nav_graph_home)

        NavigationUI.setupWithNavController(toolbar_home, navController)
    }

    fun onBackPressed(): Boolean {
        return navController.navigateUp()
    }
}

Upvotes: 4

Views: 825

Answers (1)

M. Akar
M. Akar

Reputation: 1865

Whenever onStart() is called, NavigationUI.setupWithNavController() is called again which resets the navigation. Move this call to onViewCreated() so that the navigation setup is not done every time the fragment pauses and restarts.

Upvotes: 2

Related Questions