Thanks this is really helpful! Only issue I am having is a delay before the drag begins. I move my finger and its a 1/2 second before the camera starts moving. Also when I stop moving my finger the camera continues to move (although I can work around this by exiting the state when my finger stops).
I am in the action the whole time so its always active. And I have tried different combinations of 'smoothness' and 'speed', but nothing removes the lag for me. Any ideas?