I read in the docs that iCloud doesn’t support garbage collection, and that Apple recommends using Automatic Reference Counting (ARC). Also, in the “Transitioning To ARC Release Notes”, there is the following question and answer:
This brings up the question about ASOC. Is GC mandatory for ASOC apps, or can you use ARC? Looking at the NSFileCoordinator reference, it’s clear that you would have to use Objective-C to use iCloud (because all the methods use blocks), but is it possible to have mixed ASOC/Obj-C apps that use iCloud, or will the memory management issues make that impossible?
No. One that uses ASObjC and some Objective-C could. It would have to be sandboxed to get in the app store, and it would have to be 10.8-only to support ARC in ASObjC.