https://github.com/gonzalezreal/rxswift-gentle-introduction
Swift has prompted the adoption of functional programming idioms and styles among app developers. If you have been running from this “functional weirdness” it is time to stop and embrace it.
Reactive Functional Programming is one of these idioms, and it is becoming quite popular thanks to ReactiveX (also known as Rx) and its Swift incarnation, RxSwift.