[kreeger]

While I like Swift (from what I've played with it, around SourceKitService crashing every two seconds), it doesn't provide you with the "just enough rope" that Objective-C does. Many of Objective-C's best capabilities lie in its ability to do some crazy things with metaprogramming (much like Ruby). This is a terrific introduction to that. I'd love to see a full-on book dedicated to the subject, TBH.

As an aside, I can't say I've ever seen these Genius annotations in a blog post before, but the way they're used here make this read like a chapter from a textbook with really useful sidebars. I hope this sort of thing catches on with other development blogs.