Also, don't get me started on the current state of "documentation." At one time, Apple had a huge team of ridiculously overqualified documentation people. They often had better chops than the engineers.
It was amazing, and spoiled me. There was a similar set of books about BSD UNIX, as well. Don't remember the exact title, but it was pretty awesome.
Right now, it looks like they are relying completely on, on headerdoc comments.
It can work, but someone needs to spend a lot of time on these comments, and they need to do so, at a “holistic” level, coordinating all the various systems.
They have done a fairly good job, so far, but it’s really starting to fray; especially in the newer systems.