iOS NSData 轉 UInt8 array

extension NSData {
    func getByteArray() -> [UInt8]? {
        var byteArray: [UInt8] = [UInt8]()
        for(var i = 0;i < self.length; i++) {
            var temp: UInt8 = 0
            self.getBytes(&temp, range: NSRange(location: i, length: 1))
            byteArray.append(temp)
        }
        return byteArray
    }
}