iOS: If you want to create an iOS app or a Mac app, Apple would like you to use their new programming language, Swift. For those new to coding, Swifty is one of the easiest and simplest way to get started learning.
Swifty walks you through the basics of coding, starting with running your first program (printing your name) and learning about variables and functions. The tutorials are optimised for the iPhone's and iPad's touch interface, so instead of typing in tons of code, you'll be shown an explanation of new programming concepts then some lines of code with some options missing. Tap or type to choose an option, then run the code to reveal the result.
This format makes it ideal for learning on the go and in short sprints. To access all 200+ interactive lessons, you'll need to buy the in-app upgrade ($US2.99), but the first chapter with 13 lessons covering Swift basics is free to try.