I'm pretty sure this notification is only meant for apps using the Objective-C garbage collector, as the notification mentions that the GC was deprecated a while ago. I don't think a lot of Mac developers used the Objective-C GC anyway.
Finally Apple mentions the following in it's migration document [0]:
Is GC (Garbage Collection) deprecated on the Mac?
Garbage collection is deprecated in OS X Mountain Lion v10.8, and will
be removed in a future version of OS X. Automatic Reference Counting is
the recommended replacement technology. To aid in migrating existing
applications, the ARC migration tool in Xcode 4.3 and later supports
migration of garbage collected OS X applications to ARC.
Based on the above statement, my guess is that's Xcode has some build-in tools to convert GC code to ARC code, making the transition easier.
Finally Apple mentions the following in it's migration document [0]:
Based on the above statement, my guess is that's Xcode has some build-in tools to convert GC code to ARC code, making the transition easier. [0]: https://developer.apple.com/library/ios/releasenotes/Objecti...