I enjoyed and learned a lot from the 1st edition. I just downloaded the beta of the 2nd version and it looks like a major update – well worth the $21, even in this early beta form. Looking forward to reading it from cover to cover.
I did skim through for a couple of bits I’m particularly keen to learn more about – NSOutlineView and NSIncrementalStore. I’d really like to see more coverage of using Core Data with NSOutlineView. You mention it and caution against using NSTreeController, but, we could we get a little more discussion and some code?
Also, please consider adding a chapter on NSIncrementalStore (or AFIncrementalStore). Particularly for iOS, the ability to hook into a networked database so cleanly is very appealing, but there’s very little information out there on the topic. It seems like a much better approach than Sync Services or Distributed Core Data, or even iCloud, for that matter.