Thanks very much for the response. I'd been following this tutorial initially:
Gravity Tutorial for iPhone Part 1 | BIT-101 Blog
Which made a lot of sense to me but it only animates one UIImageView (which works fine).
Thanks for the pointer to the Cocos2d code. I think I shall investigate.
Thanks also for the tip about the [init] - I've put that in there now.
All the best,
Ian
