Edudjr

func luhnCheck(_ number: String) -> Bool {
    var sum = 0
    let digitStrings = number.reversed().map { String($0) }

    for tuple in digitStrings.enumerated() {
        if let digit = Int(tuple.element) {
            let odd = tuple.offset % 2 == 1

            switch (odd, digit) {
            case (true, 9):