Cocoa control for keywords/tags

I want to build a keyword/tag feature for my Cocoa application. Is there a tutorial or example of how a control that sets keywords/tags works? I want it to look something like the Keywords window in iPhoto that you get from Window->Show Keywords.

From stackoverflow

• There is a built in control for this called NSTokenField, it's a simple subclass of a NSTextField. You supply a string and a set of delimiters and it automatically tokenizes them.