Objective-C doesn't call it methods. You send messages to an Object. The Object might or might not respond to the Message, which doesn't automatically cause it to fail. It can keep going.
This is why if you try and access a method on an Objective-C object that doesn't exist, you simply get a "Foo may not respond to -bar" warning rather than an error. This is one of my least favorite things about Objective-C.