lifecycle-listener-pt6.kt

inline fun ViewPager2.onPageSelected(lifecycleOwner: LifecycleOwner, 
                                     crossinline listener: (position: Int) -> Unit) { 
    object : OnPageChangeCallback() {
        override fun onPageSelected(position: Int) = listener(position)
    }.let {
        LifecycleEventDispatcher(lifecycleOwner,
            onStart = { registerOnPageChangeCallback(it) },
            onStop = { unregisterOnPageChangeCallback(it) })
    }
}