Zeroing Weak References in ARC

Question

If my reading of Mike Ash\'s \"Zeroing Weak References\" writeup is correct, weak references are like assign references without ARC. However, if the referenced

Answer 1

It's mostly right, but assign properties are still treated the same as they ever were, only weak ones are zeroing. Another caveat is that zeroing weak references are only available in Mac OS X ≥ 10.7 and iOS ≥ 5. While the rest of ARC was backported to 10.6 and iOS 4, weak references cannot be used at all on these OS's.