Cocoa Programming for OS X: The Big Nerd Ranch Guide

Delegation

Let’s start with a story: Once upon a time, there was a man with no name. Knight Industries decided that if this man were given guns and wheels and booster rockets, he would be the perfect crime-fighting tool. First they thought, “Let’s subclass him and override everything we need to add the guns and wheels and booster rockets.” The problem was that to subclass Michael Knight, they needed to wire his insides to the guns, wheels, and booster rockets - a time-consuming task requiring lots of specialized knowledge. So instead, Knight Industries created a helper object, the Knight Industries 2000, or “KITT,” a well-equipped car designed to assist Michael Knight in a variety of crime-fighting situations.

While approaching the ...