Some potentially useful Swift libraries:

Area Library Comments
GCD Async appears to be a simple useful framework
Future, Promises BrightFutures Swift futures and promises. See also Searching for a Swift Future library
Mocking HTTP Nocilla  
NSDate TimePiece Various NSDate helpers
Keychain KeychainAccess Keychain API needs wrapping
JSON SwiftyJSON, Argo, Gloss, Freddy, … Argo is modelled after Haskell’s Aeson which might put of some developers; SwiftyJSON looks possibly simpler and Gloss appears to be inspired by Argo. “Freddy is type safe and idiomatic” and finally a comparison of JSONJoy, SwiftyJSON & OCMapper
Testing Assertions, Quick, FBSnapShotTestCase Assertions: This is a Swift µframework providing simple, flexible assertions for XCTest in Swift; Quick: Quick is a behavior-driven development framework for Swift and Objective-C. Inspired by RSpec, Specta, and Ginkgo. FBSnapShotTestCase: Compares a snapshot to a “reference image” stored in your source code repository and fails the test if the two images don’t match.
QuickCheck style testing Fox, SwiftCheck Similar to QuickCheck on Haskell, see presentation on Fox and the Erlang Elevator QuickCheck example mentioned in the talk. From SwiftCheck: “With the power of SwiftCheck and a sufficiently expressive testing suite, we can begin to check our programs not for individual passing cases in a few scattershot unit tests, but declare and enforce immutable properties that better describe the intent and invariants of our programs.”
Managing complexity of interactions ReactiveCocoa Cocoa framework inspired by Functional Reactive Programming. It provides APIs for composing and transforming streams of values over time
Result<Value, Error> Result Result<Value, Error> values are either successful (wrapping Value) or failed (wrapping Error). This is similar to Swift’s native Optional type, with the addition of an error value to pass some error code, message, or object along to be logged or displayed to the user.
“Libraries to simplify development of Swift programs by utilising the type system” TypeLift SwiftCheck (QuickCheck for Swift), Swiftx (Functional data types and functions for any project), Focus (Optics for Swift), Aquifer (Functional streaming abstractions in Swift), Swiftz (Swiftz is a Swift library for functional programming), Concurrent (Functional Concurrency Primitives), Operadic (Standard Operators for the working Swift Librarian), Basis (Pure Declarative Programming in Swift, Among Other Things), Algebra (Abstract Algebraic Structures in Swift)
code composition Stream Lazy streams in Swift
Logging CleanroomLogger The API provided by CleanroomLogger is designed to be readily understood by anyone familiar with packages such as CocoaLumberjack and log4j
HTTP networking library Alamofire Swift version of AFNetworking
Nothing but net(working) Swish Protocol based http library
Functional programming in Swift Swiftz Swiftz implements higher-level data types like Arrows, Lists, HLists, and a number of typeclasses integral to programming with the maximum amount of support from the type system
Dependency Injection Dip “Dip is inspired by .NET’s Unity Container”. See also: “Function programming in Swift” 2015 conference - DI in Swift video. I’m sure there are other DI frameworks out there…
Autolayout PureLayout PureLayout extends UIView/NSView, NSArray, and NSLayoutConstraint with a comprehensive Auto Layout API that is modeled after Apple’s own frameworks. PureLayout is a cross-platform Objective-C library that works (and looks!) great in Swift
AttributedStrings BonMot BonMot is a Swift attributed string library
Threading Async Syntactic sugar in Swift for asynchronous dispatches in Grand Central Dispatch

I still haven’t found Swift equivalents of:

Area Library Comments
Mocking OCMock Extensive use of Swift protocols minimises the need for mocks. Using locally defined classes for mocking see Mocking in Swift. Quote: “In Swift, classes can be declared within the definition of a function, allowing for mock objects to be extremely self-contained. Just declare a mock inner-class, override and necessary methods”

See also: