FragmentViewBindingProperty.kt

class FragmentViewBindingProperty<T : ViewBinding>(
    private val viewBinder: ViewBinder<T>
) : ReadOnlyProperty<Fragment, T> {

    private var viewBinding: T? = null
    private val lifecycleObserver = BindingLifecycleObserver()

    @MainThread
    override fun getValue(thisRef: Fragment, property: KProperty<*>): T {
        checkIsMainThread()
        this.viewBinding?.let { return it }

        val view = thisRef.requireView()
        thisRef.viewLifecycleOwner.lifecycle.addObserver(lifecycleObserver)
        return viewBinder.bind(view).also { vb -> this.viewBinding = vb }
    }

    private inner class BindingLifecycleObserver : DefaultLifecycleObserver {

        private val mainHandler = Handler(Looper.getMainLooper())

        @MainThread
        override fun onDestroy(owner: LifecycleOwner) {
            owner.lifecycle.removeObserver(this)
            // Fragment.viewLifecycleOwner call LifecycleObserver.onDestroy() before Fragment.onDestroyView().
            // That's why we need to postpone reset of the viewBinding
            mainHandler.post {
                viewBinding = null
            }
        }
    }
}