There are several variations of arc4random() that can be used to create random numbers in Swift. Two common examples follow.
let randomNum = arc4random() println("randomNum: \(randomNum)")
Create a random number less than a specified upper bound:
let x = arc4random_uniform(100) println("x: \(x)")
arc4random is part of the Standard C library. Type ‘man arc4random’ in a terminal to read more.