Kotlin extension methods to simplify saving and restoring a recyclerviews scroll postion

Recycler.kt

import android.os.Bundle
import android.os.Parcelable
import android.support.v7.widget.RecyclerView

/**
 *     We have to handle restoring a recyclerviews scroll position oneself.
 *     Add a extension field so we don't have to handle the key ourselves anymore
 *     Add a post to avoid some bug where recyclerview does not restore scroll position
 *
 *     override fun onSaveInstanceState(outState: Bundle) {
 *         super.onSaveInstanceState(outState)
 *         viewModel.saveState(outState)
 *         binding.recycler.saveLayoutManagerState(outState)
 *      }
 *
 *      override fun onRestoreInstanceState(savedState: Bundle) {
 *         super.onRestoreInstanceState(savedState)
 *         binding.recycler.postRestoreLayoutManagerState(savedState)
 *      }
 */

val RecyclerView.KEY_RECYCLER_VIEW_STATE: String
    get() = "recycler_view_state"

fun RecyclerView.saveLayoutManagerState(outState: Bundle) {
    val layoutState = this.layoutManager.onSaveInstanceState()
    outState.putParcelable(this.KEY_RECYCLER_VIEW_STATE, layoutState)
}

fun RecyclerView.postRestoreLayoutManagerState(savedState: Bundle?) {
    val layoutState = savedState?.getParcelable<Parcelable>(this.KEY_RECYCLER_VIEW_STATE)
    this.post { layoutManager.onRestoreInstanceState(layoutState) }
}