Apple has issued a warning to developers that it has deprecated the garbage collection feature used for memory management in favor of Automatic Reference Counting, or ARC. New Mac apps and app updates submitted to the Mac App Store starting in May will be required to use ARC.
Apple tells developers it's time for a new memory management system
In a note to developers, Apple said,
Beginning May 1, 2015, new Mac apps and app updates submitted to the Mac App Store may no longer use garbage collection, which was deprecated in OS X Mountain Lion. Instead, migrate your apps to Automatic Reference Counting, using the migration assistant in Xcode to help with this transition. Apps may continue to use retain/release for manual memory management.
Mac apps currently available through Apple's Mac App Store won't stop working when the required code change goes into place, and apps that are offered outside of the company's curated store won't be bound by the requirement.
Developers interested in learning more about making the move from garbage collection to ARC can check out Apple's Transitioning to ARC release notes.