Learning functional programming can be very intimidating. Just the other day, someone on Twitter recommended I read this ebook. Ok, maybe the book is ok, but the landing page sure is intimidating!
However, as I've been learning more and more functional programming, I found myself really liking the higher-level concepts (which make a lot of sense, and don't even mention things like monads or functors). And as I'm starting to understand the lower-level functional implementation, I find myself understanding Swift and better programming patterns a lot more.
This weekend, I attended the Functional Swift Conference, and one thing that stood out was how interested iOS developers are in learning about functional programming and how excited functional programmers (experts in Haskell, etc.) are to bring a bit of functional programming to iOS with Swift. In fact, @andy_matuschak gave a whole talk about how to encourage team members to write code in a more functional way without isolating them.
Since Swift is so new and there aren't best practices / patterns just yet, I highly recommend learning functional programming to have a better understanding of what decisions to make and when to make them. You'll be seeing a lot more from me on the topic!