SkyFloatingLabelTextField is a beautiful, flexible and customizable implementation of the space saving "Float Label Pattern". This design enables adding context to input fields that is visible at time of typing, while minimizing the additional space used to display this additional context.
Concepts like Functors, Applicative Functors, Monads, and Monoids in Haskell all seem totally incomprehensible at first, but translating them into Swift can make things much clearer. Each of these concepts are essentially protocols that tie together Arrays, Optionals, Streams, Promises, and a host of other data types. They make way more sense when written in Swift with descriptive variable names. Understanding them can give you a deeper understanding of programming paradigms like Reactive Programming and Railroad-Oriented Programming.