I'm having trouble getting a handle on what's thread-safe in iOS drawing and
what's not. The trouble is that the docs are so coy (and out-of-date, as far as
I can tell). To the extent that the docs do say anything clear, it's all
negative:
You cannot use any UIKit's drawing methods when
UIKit graphics drawing methods are thread safe on iOS 4.0 or greater. If you
are referring to the QA on using a CATiledLayer with UIView, that probably does
indeed need to be updated, but the methods it warns against should all be safe
to use from secondary threads on iOS 4.0 or later.
On Dec
