Swift3.0 - 键盘相关

 NotificationCenter.default.addObserver(self, selector: #selector(keyBoardWillShow(notification:)), name: NSNotification.Name.UIKeyboardWillShow, object: nil)
    
 NotificationCenter.default.addObserver(self, selector: #selector(keyBoardWillHide(notification:)), name: NSNotification.Name.UIKeyboardWillHide, object: nil)


  //  触发时间
 func keyBoardWillShow(_ notification: Notification){
     guard let frame = notification.userInfo?[UIKeyboardFrameEndUserInfoKey] else{
        return
    }
    let y = (frame as! NSValue).cgRectValue.origin.y
  }