A Pinterest style "waterfall of images" style UICollectionView layout from Nelson, useful directly if you need this style of view or for education if you haven't dug into how a custom collection view layout is built yet. I am surprised there haven't been more of these layout classes popping up. Maybe I missed some?
We haven't had much low level content here in a while but this Friday Q&A should make up for that. Mike Ash takes an in depth look at the buggiest of all functions, objc_msgSend.
Ever wanted to know what the Gunning Fog score for a piece of text was? This is a niche one but this NSString category by Ryan Nystrom implements Dave Child's text-statistics which gives various readability statistics.
Logan Collins with a little experiment to visualise the face detection features available as part of Core Image. It's easy to forget that we have access to this powerful feature.