New Objective-C features are introduced with new versions of the compiler (and Xcode tools/SDK), but each feature may be deployed on different versions of iOS/O

New Objective-C features are introduced with new versions of the compiler (and Xcode tools/SDK), but each feature may be deployed on different versions of iOS/OS X (depending on how much support they need from the underlying runtime/operating system). This table breaks it down: https://developer.apple.com/Library/mac/releasenotes/ObjectiveC/ObjCAvailabilityIndex/index.html https://developer.apple.com/Library/mac/releasenotes/Objecti...