I found BlockKit [1] to be very useful for any Ruby-like collection methods. BlockKit, as the name says, uses blocks extensively to provide all the most common collection methods one would find in Ruby. Some examples of these methods, taken from the NSArray(BlocksKit) [2] documentation are "each", "apply", "map" & "reduce". There are much more.

[1]: https://github.com/pandamonia/BlocksKit [2]: http://pandamonia.github.io/BlocksKit/Documentation/Categori...