allow you to add a "pull to refresh view"and "infinite scrolling view" to anywhere in ScrollView(like TableView and CollectionView), support many themes and also theme changing.
if a infinite scrolling process finishes while a pull to refresh process is still in refreshing, then the pulltorefresh view would not reset to correct content offset.
since in some cases, the refresh view would be seen at the top of the scrollview, i am considering adding a cover view on the refresh view. of course users could feel free to decide whether it should exist or customise it.