Ash Furrow’s forthcoming book looks good:
Ever wanted to learn about functional programming, but didn't know where to start? Grab this book to learn about applied, real-world use of functional reactive programming on iOS using ReactiveCocoa.
Update (2013-10-29): Drew McCormack:
And it is a good introduction. It’s not dauntingly long, so if you have a passing interest, you can easily read it in a few hours without having to commit to a whole new career. I recommend you take a look if FP is something that you have wondered about.
Book Cocoa iOS Mac Model-View-ViewModel (MVVM) Objective-C Programming ReactiveCocoa RXCollections‎
Marco Arment:
In the early days of iOS podcast playback, when Apple first implemented multiple speed settings, they used inaccurate labels. Apple’s “2x” setting, for instance, was really 1.5x. Their “1.5x” setting was really 1.25x. And their “½x” setting was really 0.8x.
Apple’s Podcasts app now uses the advertised speeds, but Downcast uses the old ones.
Apple Podcasts Downcast iOS iOS App Overcast Podcasts
The Little Book of Semaphores (via Jonathan Dann):
The Little Book of Semaphores is a free (in
both senses of the word) textbook that introduces the principles of
synchronization for concurrent programming.
In most computer science curricula, synchronization is a module
in an Operating Systems class. OS textbooks present a standard
set of problems with a standard set of solutions, but most students
don't get a good understanding of the material or the ability
to solve similar problems.
The approach of this book is to identify
patterns that are useful for a variety of synchronization
problems and then show how they can be assembled into solutions.
After each problem, the book offers a hint before showing a
solution, giving students a better chance of discovering solutions
on their own.
Book CS Theory Programming