This month's CocoaHeads features two talks.
He sends the following summary:
BJ Miller will talking about Class Clusters. As usual, BJ will speak from experience on a feature that he has found solves particular problems for him. Here's his description:
"Class clusters is a design paradigm in objective-c which groups private subclasses under a public abstract superclass. class clusters are useful for many things, and have really been brought to attention with the recent iOS 7 update. i will show how they work and demo how to make an app iOS 6- and iOS 7-compatible with a short example."
Sounds like two great talks! You'll want to be there.