I’ve mentioned a few utility objective-c utility libraries inspired by Underscore.js most recently the Aterism library.
Here’s an open source library that provides a number of functional programming helper methods in the style of Underscore and Lo-Dash for those working with the new Swift programming language called Dollar $wift from Ankur Patel.
Here are few examples of Dollar.$swift in action from the readme:
$.compact([3, nil, 4, 5]) as NSObject == [3, 4, 5]
$.initial([3, 4, 5], numElements: 2) as Int == 
$.last([3, 4, 5]) as Int == 5
You can find Dollar.$wift on the home page here.
A nice library for anyone working with Swift.