WallFragment.kt

class WallFragment : Fragment() {

    private lateinit var itemSelector: Selector
    private lateinit var model: SharedViewModel

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        model = activity?.run {
            ViewModelProviders.of(this).get(SharedViewModel::class.java)
        } ?: throw Exception("Invalid Activity")
        itemSelector.setOnClickListener { item ->
            //model.data.value = item
        }
    }
}