https://github.com/apple/swift/blob/master/docs/CompilerPerformance.md

This document is a guide to understanding, diagnosing and reporting compilation-performance problems in the swift compiler. That is: the speed at which the compiler compiles code, not the speed at which that code runs.

While this guide is lengthy, it should all be relatively straightforward. Performance analysis is largely a matter of patience, thoroughness and perseverance, measuring carefully and consistently, and gradually eliminating noise and focusing on a signal.

http://ericasadun.com/2016/07/18/dear-erica-no-case-enums/

Dear Erica, Why would you create an enum with no cases?
This is such a great question! No-case enumerations represent a fairly obscure Swift “power tool”, and one that most developers are unaware of.

https://github.com/lxcid/ListDiff

It is an implementation of an algorithm by Paul Heckel that calculates the diff between 2 arrays.

https://github.com/quicktype/quicktype-xcode

quicktype infers types from sample JSON data, then outputs strongly typed models and serializers for working with that data in Swift, C++, Obj-C++, Java and more. This extension adds native quicktype support to Xcode 9.