Android Keep Track of Edit and View Mode With LiveData (Fragment, Kotlin)

class BatchViewModel : ViewModel() {    val editModeEvent = MutableLiveData<Event<Boolean>>(Event(false))    internal var editMode: Boolean        get() = editModeEvent.value!!.peek()        set(value) {            editModeEvent.value = Event(value)        }}

class BatchFragment : Fragment() {    private val viewModel: BatchViewModel by viewModels()    // private val args: BatchFragmentArgs by navArgs()    // private lateinit var adapter: LocalAdapter    override fun onCreate(savedInstanceState: Bundle?) {        super.onCreate(savedInstanceState)        setHasOptionsMenu(true)    }    override fun onCreateView(        inflater: LayoutInflater, container: ViewGroup?,        savedInstanceState: Bundle?    ): View? {        return inflater.inflate(R.layout.batch, container, false)    }    override fun onCreateOptionsMenu(menu: Menu, inflater: MenuInflater) {        inflater.inflate(R.menu.batch, menu)        val editMenuItem = menu.findItem(R.id.action_edit)        val saveMenuItem = menu.findItem(R.id.action_save)        if (viewModel.editMode) {            editMenuItem.isVisible = false            saveMenuItem.isVisible = true        }        else {            editMenuItem.isVisible = true            saveMenuItem.isVisible = false        }        super.onCreateOptionsMenu(menu, inflater)    }    override fun onOptionsItemSelected(item: MenuItem): Boolean {        return (when(item.itemId) {            R.id.action_save -> {                viewModel.editMode = false                true            }            R.id.action_edit -> {                viewModel.editMode = true                true            }            else ->                super.onOptionsItemSelected(item)        })    }    override fun onActivityCreated(savedInstanceState: Bundle?) {        super.onActivityCreated(savedInstanceState)        // viewModel.editMode = args.default.isNew        viewModel.editMode = true        initObserver()    }    private fun initObserver() {        viewModel.editModeEvent.observe(viewLifecycleOwner, Observer { event ->            event.getIfPending()?.also { isEdit ->                activity?.invalidateOptionsMenu()                // adapter.notifyDataSetChanged()                // do something to update the UI            }        })    }}

<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto">
    <item
        android:id="@+id/action_edit"
        android:title="Edit"
        app:showAsAction="ifRoom" />

    <item
        android:id="@+id/action_save"
        android:title="Save"
        app:showAsAction="ifRoom" />
</menu>