By a series of strange events I have found myself an author on several different books. I am probably biased but I think they're pretty good.
The Kerbal Player's Guide
So if you've not played Kerbal Space Program you are missing out on one of the coolest rocket based games ever made. You play as the director of a space program for these weird little green space obsessed creatures. Design and build rockets, fly around space, land on planets, and explode a great deal. Oh and I co-authored a book that covers pretty much everything about it with Jon Manning, Paris Buttfield-Addision, Paul Fenwick, and Alasdair Allan
This is pretty much a look into everything you can do in Swift and Cocoa using the Apple developer tools. The thing I like about it is that we actually build an entire app for macOS, iOS, and WatchOS from the ground up instead of just snapshot examples.
Swift Development with Cocoa
This was the first Swift book I worked on and is kinda the same as Learning Swift but isn't as focussed in it's approach to covering the topic. Was written way back when Swift 1.0 came out, so is out of date now but might still be interesting to those who really miss the ++ operator.
Learning Cocoa with Objective-C
The first book I ever worked on. Is effectively the same approach as Swift Development but uses ol' Obj-C instead. In some respects this means it is less out of date than Swift Development with Cocoa but it would mean having to use Obj-C again...