we are aware that there are some issues with the game on some Apple devices when updated to iOS 8. We are working on a fix and will be submitting it to Apple within 24 hours, so you should see it within the next few days.
The game is still playable, but you may notice that it is a bit more zoomed in than usual.
Apologies for the inconvenience, and thanks for your patience!
UPDATE - the fix is now live, so please make sure to update your build!