Support floating headers

[orta]

Something that would sit under the header, but then will scroll until it's at the top. Could also provide a callback for when the view is 'stuck'.

[ashfurrow]

Nice, could be a good use of UICollectionView's supplementary views, to keep configuration largely out of this framework and in the app.

[orta]

This is in - and it uses that :D

[ashfurrow]

Neato!