FriendsFragment.kt

class FriendsFragment : BaseFragment() {

    override fun layoutId(): Int = R.layout.fragment_friends

    private lateinit var friendsViewModel: FriendsViewModel

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        appComponent.inject(this)

        friendsViewModel = viewModel(viewModelFactory) {
            observe(state, ::onFriendsStateChange)
        }
    }

    private fun onFriendsStateChange(state: FriendsState?) {
        when (val friendsState = state!!) {
            is FriendsState.Loading -> showLoading()
            is FriendsState.Empty -> showEmptyState()
            is FriendsState.Success -> renderList(friendsState.users)
        }    
    }

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)

        friendsViewModel.loadData()
    }

  // ...
}