Are there any good, up-to-date resources on macOS internals that detail everything from the boot process to the GUI? I could only find [0], and Apple's [1] was last updated in 2013..
Jonathan Levin's MOXiL 2nd Edition volume 3 is out and I recommend you get it. 1st edition is still very good and can hold you off until the other volumes are out.
Amit Singh has a Mac OS X Internals A Systems Approach that is good we well.
There are also various talks at security conferences that detail parts of macOS/iOS.
[0] http://www.newosxbook.com/index.php?page=book
[1] https://developer.apple.com/library/content/documentation/Da...