SetFragmentFactoryActivityCallback.kt

class SetFragmentFactoryActivityCallback(
    private val newFragmentFactory: FragmentFactory
) : EmptyActivityLifecycleCallbacks {

    private val fragmentLifecycleCallbacks = 
        SetFragmentFactoryFragmentCallback(newFragmentFactory)

    override fun onActivityCreated(activity: Activity, savedInstanceState: Bundle?) {
        if (activity is FragmentActivity) {
            val fragmentManager = activity.supportFragmentManager
            fragmentManager.fragmentFactory = newFragmentFactory
            fragmentManager.registerFragmentLifecycleCallbacks(
                fragmentLifecycleCallbacks,
                true // recursevly register the callbacks for children fragments
            )
        }
    }
}


private class SetFragmentFactoryFragmentCallback(
    private val newFragmentFactory: FragmentFactory
) : FragmentManager.FragmentLifecycleCallbacks() {

    override fun onFragmentPreAttached(
        fm: FragmentManager, f: Fragment, context: Context
    ) {
        f.childFragmentManager.fragmentFactory = fragmentFactory
    }
}