Ole Begemann mentioned last week on Twitter that GitHub would soon be full of UICollectionViewLayout subclasses and Jonathan Wight took the baton this week and published an implementation of Coverflow as a UICollectionViewLayout subclass. Being able to craft these subclasses with ease is going to become a core iOS development skill over the next year so dig into the code and take a look at a real world example.
Soroush Khanlou with a nice little CAKeyframeAnimation subclass for easily implementing a wide range of bounce effects in your iOS apps. One for the Core Animation toolbox.
More Core Animation goodness from Kellen Styler. This is not a newly published article but I happened across it this week and it's a great run down of everything you might want to know about CALayer shadows.