How to make a number not repeat itself more than 2 times?

everyone ! Lets say we have

let random = arc4random_uniform(6)

how do i make it not repeat the same number more then two times ? I tried doing it like this :

let previousNumber = Int()
let lastNumber = Int ()

let random = Int(arc4random_uniform(6))

if random == previousNumber {
  lastNumber = previousNumber
} else {
previousNumber = random 
}

if random == lastNumber {
random = Int(arc4random_uniform(6))
}

But it didn't work. I am new to swift and i didn't find a topic about this on the new swift 3 code. Thank you !