我想追加两个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)
致命错误:在展开Optional值时意外发现nil