Mike Ash has turned his Friday Question and Answer series into a book, which you can read on your Kindle or in iBooks.

Mike's a super smart guy, he's a good technical writer, and self publishing is pretty damn awesome. So I encourage you to check this out.

(I know whenever I need to look up something on Obj-C Blocks, I always start at Mike's website. And if you aren't already reading his blog, well- you should).