Apple公告2015年5月所新開發的App或更新上架時，如有使用Garbage Collection必需要更新為ARC(Automatic Reference Counting)，原文如下：
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.
如何由Garbage Collection升級為ARC參考Transitioning to ARC Release Notes