I want to append two NSData:
var actionIdData :NSData = NSData(bytes: &actionId, length: 2)
var payLoad : NSData = NSData(bytes: &message, length: 9)
var messageData : NSMutableData!
messageData.appendData(actionIdData)
messageData.appendData(actionIdData)
fatal error: unexpectedly found nil while unwrapping an Optional value