Here’s an extensive functional toolbelt for objective-c for manipulating Foundation’s data structures from Underscore.m founder Robert Böhnke (Robb) called Asterism that takes a different approach from the previously mentioned libraries as it does not use a Ruby inspired syntax or categories.
As Robb stated in his e-mail:
It uses overloaded C-functions instead of categories (like BlocksKit and Objective-Sugar do). This allowed me to unify the interface for all kinds of different data-structures (NSArray, NSDictionary, NSSet, NSOrderedSet and occasionally even id< nsfastnumeration >)
Here’s an example from the readme showing the Asterism ASTEach command for iterating through an array:
You can find Asterism on the home page here.
A very nice library for working with data structures wihth a very clean syntax.