I am not sure if this is even possible within the realm of iOS and Objective-C, but, being able to do this would simplify so so much...
I would like to be able to execute one (or more) actions called by @selector or similar way, whenever an NSObject is modified in memory. An alternative to a callback, is a polling mechanism via a timed thread, but this seems excessive and inefficient.
I have not been able to find answers or examples to anything like this yet, but, there may be someone who knows for sure.