AspectCocoaExamples - part of AspectCocoa
A place for examples of what we intend for Aspects to be able to accomplish, and examples of what we’d like to be able to have Aspects accomplish.
Suppose we have an NSTextView and we want it to update some other control every time someone clicks into it. Well, we could look at http://developer.apple.com/documentation/Cocoa/Reference/ApplicationKit/ObjC_classic/Classes/NSTextView.html But, what if we could just write a couple of lines of code that meant that whenever any method gets called on NSTextView or its superclasses, we NSLog some information about that method call. Now we can run an application, click in the box and see which methods got called. So now we can subclass NSTextView and we know just what method to override.
you may also be interested in ACLoggingAdvice, InvarianceCheckingWithAspectCocoa, or AspectCocoaDocumentation