NSNotification

• object is self
• Broadcast notification:

  let center=NSNotificationCenter.defaultCenter()
  let notification=NSNotification(name: GPXURL.Notification, object: self, userInfo: [GPXURL.Key:url])
  center.postNotification(notification)
  

• Listen:

let center=NSNotificationCenter.defaultCenter()
let queue=NSOperationQueue.mainQueue()
let appDelegate=UIApplication.sharedApplication().delegate

center.addObserverForName(GPXURL.Notification, object: appDelegate, queue: queue){ (notification) in
            if let url=notification?.userInfo?[GPXURL.Key] as? NSURL{
                self.textView.text="Recieved \(url)"
            }
        }

• object is UITextFieldTextDidChangeNotification

  let center=NSNotificationCenter.defaultCenter()
  let queue=NSOperationQueue.mainQueue()
  center.addObserverForName(UITextFieldTextDidChangeNotification, object: nameTextField, queue: queue) { notification in
  
   }
  }