What does the exclamation mark mean in an Objective-C if statement?

Question

I am wondering what the exclamation mark in if(!anObject) means.

Answer 1

As everyone has mention is just a NOT operator, what I believe might have confused you is the brackets [], Objective C, comes from a language called small talk, that uses a send message approach to objects, the brackets are used to send that message. The messages are really functions.