This post by the folks at Functional Works explains what functional programming is and why it makes you better. Although it is not about Swift, the concepts obviously also apply there.
Nacho Soto demonstrates how functional reactive programming helps write clearer, more concise and modular code in modern applications using ReactiveCocoa in Swift.
Ole Begemann writes about the possibility to extend pattern matching in Swift.
In this follow-up article Ole explains the differences of Ranges and Intervals in Swift.
As always Russ Bishop summarizes all changes to Swift that were introduced with 2.1 beta.
Simon Gladman shows the power of Swift's Protocol Extensions to apply a CIGaussianBlur Core Image filter to any UIView with no developer overhead.
Ash Furrow wrote quite a lot about the Model View ViewModel pattern. This time he writes about his experience with MVVM in conjunction with Swift.
Watchdog is a class that logs excessive blocking on the main thread. It is written in Swift and really easy to use.
SwiftGo is a pure Swift/C library that provides Go's concurrency features in Swift 2. It has no Foundation dependencies and should also work on Linux when Swift is open-sourced later this year.
Nuke is an advanced pure Swift framework for loading, caching, processing, displaying and preheating images. It uses latest advancements in iOS SDK and doesn't reinvent existing technologies.
Enhance your app / service with a photo editor. It's fully customizable and SDKs available for iOS and HTML5.