UUID from and to two UInt64

UUID+UInt64.swift

extension UUID {
    init(numbers: (UInt64, UInt64)) {
        var firstNumber = numbers.0
        var secondNumber = numbers.1
        let firstData = Data(bytes: &firstNumber, count: MemoryLayout<UInt64>.size)
        let secondData = Data(bytes: &secondNumber, count: MemoryLayout<UInt64>.size)

        let bytes = [UInt8](firstData) + [UInt8](secondData)

        let tuple: uuid_t = (bytes[0], bytes[1], bytes[2], bytes[3],
                             bytes[4], bytes[5], bytes[6], bytes[7],
                             bytes[8], bytes[9], bytes[10], bytes[11],
                             bytes[12], bytes[13], bytes[14], bytes[15])

        self.init(uuid: tuple)
    }

    var intTupleValue: (lower: UInt64, upper: UInt64) {
        let tuple = self.uuid

        let firstBytes: [UInt8] = [tuple.0, tuple.1, tuple.2, tuple.3,
                                   tuple.4, tuple.5, tuple.6, tuple.7]

        let secondBytes: [UInt8] = [tuple.8, tuple.9, tuple.10, tuple.11,
                                    tuple.12, tuple.13, tuple.14, tuple.15]

        var firstData = Data(firstBytes)
        var secondData = Data(secondBytes)
        let first = withUnsafeBytes(of: &firstData) {
            $0.load(as: UInt64.self)
        }
        let second = withUnsafeBytes(of: &secondData) {
            $0.load(as: UInt64.self)
        }

        return (first, second)
    }
}