Reference Counting

"To understand reference counting, imagine a puppy. When the puppy is born, it has an owner. That owner later gets married, and the new spouse also becomes an owner of that dog. The dog is alive because they feed it. Later on, the couple gives the dog away. the new owner of the dog decides he doesn't like the dog and lets it know by kicking it out of the house. Having no owner, the dog runs away and, after a series of unfortunate events, ends up in doggy heaven.

What is the moral of this story? As long as the dog had an owner to care for it, it was fine. When it no longer had an owner, it ran away and ceased to exist. This is how reference counting works."

iPhone Programming, the Big Nerd Ranch Guide by Joe Conway and Aaron Hillegass