[小技巧]將utc時間轉成local時間(utc time to local time)

              let dateFormatter = NSDateFormatter()
        dateFormatter.dateFormat = "yyyy/MM/dd HH:mm:ss"
        dateFormatter.timeZone = NSTimeZone(name: "UTC")
        let date = dateFormatter.dateFromString(result[indexPath.row].send_time)
  
       

        // change to a readable time format and change to local time zone            

        dateFormatter.dateFormat = "yyyy/MM/dd HH:mm:ss"
        dateFormatter.timeZone = NSTimeZone.localTimeZone()

        let timeStamp = dateFormatter.stringFromDate(date!)