Luhn check modified with enumerate

luhn.swift

func lunhCheck(number : String) -> Bool
{
    return reduce(enumerate(reverse(number).map { String($0).toInt()! }), 0) {
        let odd = $1.0 % 2 == 1
        return $0 + (odd ? ($1.1 == 9 ? 9 : ($1.1 * 2) % 9) : $1.1)
    } % 10 == 0
}

lunhCheck("49927398716")
lunhCheck("49927398717")