Aren't you living dangerously by still using garbage collection on iOS at this point? Apple keep making dire statements about how everyone needs to stop using it, so I'd be worried that iOS8 will just remove it entirely, meaning apps that use GC just wouldn't work at all on that OS...
ObjC garbage collection never existed on iOS. The issue was related to framework code that was written by Apple for an ObjC-GC environment (probably Mac OS X) and ported to a non-GC environment (iOS).
I should clarify. iOS does not have garbage collection and has never had garbage collection. The root of this bug is in old legacy cruft from the garbage collected days of OSX. The code is dormant in a lot of old CoreFoundation classes, and still causes unexpected behavior from time to time.
