An extension on Int to generate random Ints and alphanumeric strings.

IntRandom.swift

extension Int {
    func asUpperBoundForRandom() -> Int {
        return Int(arc4random_uniform(UInt32(self)))
    }

    func asLengthForRandomAlphanumeric() -> String {
        let alphabet = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789".characters
        var chars: [Character] = []
        for _ in 1...self {
            let randomIndex = alphabet.startIndex.advancedBy(alphabet.count.asUpperBoundForRandom())
            chars.append(alphabet[randomIndex])
        }
        return String(chars)
    }
}