我可以隐藏UIpicker并在其位置移动UIView吗?

我的策略是,用户将选择一个选择器,然后当他们在文本字段中键入时,选择器将消失(值已被选择并存储),文本字段(在“topView”中)将弹出,选择器将为键盘腾出空间。我可以看到我的topView试图弹出,但它没有任何效果。我可以这样做吗?还是拾取器在它上方的位置阻止了我,即即使它是隐藏的,它的空间仍然存在?

@IBOutlet weak var topHalfView: UIView!


override func viewDidLoad() {
    super.viewDidLoad()
    countyPicker.delegate = self
    countyPicker.dataSource = self

        NSNotificationCenter.defaultCenter().addObserver(self, selector: Selector("keyboardWillShow:"), name:UIKeyboardWillShowNotification, object: nil);
        NSNotificationCenter.defaultCenter().addObserver(self, selector: Selector("keyboardWillHide:"), name:UIKeyboardWillHideNotification, object: nil);
    }

    func keyboardWillShow(sender: NSNotification) {
        countyPicker.hidden = true
         self.topHalfView.frame.origin.y += 150
    }

    func keyboardWillHide(sender: NSNotification) {
        countyPicker.hidden = false
        self.topHalfView.frame.origin.y -= 150

}