While looking through the release notes for Foundation in iOS 10/macOS 10.12 Sierra, I noticed an item under “Overall API Updates”
Use of class properties, in both Swift as well as Objective-C, latter using the new “@property (class)” declaration.
Xcode 8 ships with a new versions of Clang and LLVM (800.0.2.24.1, and 8.0.0 as of the first beta). The new version of Clang adds support for class properties in Objective-C. The feature is not yet fully documented anywhere that I can find1, so I did a little experimenting.