What's the difference between a method and a selector?

Question

What the difference between a method, a selector and a message in Objective-C?

Answer 1

A method is the implementation which is run when an object or class is asked to perform some action. It is in the scope of its containing class and is therefore different when referenced through some other class. A selector is an identifier which represents the name of a method. It is not related to any specific class or method, and can be used to describe a method of any class, whether it is a class or instance method.

Simply, a selector is like a key in a dictionary. It can tell you what method someone is talking about, but only if you also have the dictionary itself (the class or object). The method is what you get when you ask for the value from the dictionary using the selector as a key.