Another one of my Swift samples for RosettaCode.org

factorial.swift

// Recursive:

func factorial(num: Int) -> Int {
    
    return num < 2 ? 1 : num * factorial(num - 1)
}

// Iterative:

func factorial2(num: Int) -> Int {

    return num < 2 ? 1 : reduce(1...num, 1, *)
}

factorial2(5)
factorial2(5)