MRCEnumerable is an category implementation of several useful methods from the Ruby Enumerable module, such as collect, inject, select, detect, reject, etc, using Objective-C blocks, and a familiar syntax.
An example of use of each extension method is available in the Tests directory, in the file named after the extension itself.
This project was initially started at Railscamp 8 in Perth, and currently extends NSArray, NSDictionary, and NSSet. Feel free to get in contact if you have any suggestions or bug reports, etc.