Extending Objects in Cocoa with Categories‎
Adding in functionality to an existing class in Cocoa is easy using categories. This can be useful for methods that should be transient or when access to the original code is restricted.
Kevin Sylvestre
A Few Reasons Cocoa Is Not That Hot
Over the past year Apple has released an amazing set of phones and tablets. While the devices are incredible the framework and language have a few shortcomings that Apple will have to address.