ios - 未调用手势识别器

Question

我已经设置了一个手势识别器，用于在用户点击文本字段外部时关闭键盘。 DismissKeyboard 函数未被调用。

我是否设置了错误的观察者或者这是一个不同的问题？此外，这是一个正在被点击的表格 View 。

代码摘录

class CommentsViewController: UIViewController, UITableViewDelegate, UITableViewDataSource {
    override func viewDidAppear(animated: Bool) {
        super.viewDidAppear(animated)
        NSNotificationCenter.defaultCenter().addObserver(self,
            selector: Selector("keyboardWillShow:"),
            name: UIKeyboardWillShowNotification,
            object: nil)
        NSNotificationCenter.defaultCenter().addObserver(self,
            selector: Selector("keyboardWillHide:"),
            name: UIKeyboardWillHideNotification,
            object: nil)
    }

    func keyboardFrameChanged(notification: NSNotification) {
        println("keyboardFrameChanged")
        let userInfo = notification.userInfo
        let key = UIKeyboardFrameEndUserInfoKey
        if let info = userInfo {
            let frameValue = info[key] as! NSValue
            let _frame = frameValue.CGRectValue()
        }
    }
    
    func keyboardWillShow(notification: NSNotification) {
        if keyboardDismissTapGesture == nil
        {
            println("dismiss")
            keyboardDismissTapGesture = UITapGestureRecognizer(target: self, action: Selector("dismissKeyboard:"))
            self.view.addGestureRecognizer(keyboardDismissTapGesture!)
        }
    }
    
    func keyboardWillHide(notification: NSNotification) {
        if keyboardDismissTapGesture != nil
        {
            println("test2")
            self.view.removeGestureRecognizer(keyboardDismissTapGesture!)
            keyboardDismissTapGesture = nil
        }
    }
    
    func dismissKeyboard(sender: AnyObject) {
        println("dismiss keyboard")
        commentTextField.resignFirstResponder()
    }

我在 dismissKeyboard 处设置了一个断点，但它甚至没有被调用。

输出

当我点击 TextView 并打开键盘时，这是输出

keyboardFrameChanged
keyboardFrameChanged
will show
dismiss

当我点击其他任何东西(试图关闭键盘)时，没有进一步的输出。

Answer 1

将手势识别器委托(delegate)设置为您自己并添加 UIGestureRecognizerDelegate 协议(protocol)。

func keyboardWillShow(notification: NSNotification) {
    if keyboardDismissTapGesture == nil
    {
        println("dismiss")
        keyboardDismissTapGesture = UITapGestureRecognizer(target: view, action: "dismissKeyboard:")
        keyboardDismissTapGesture.delegate = self
        self.view.addGestureRecognizer(keyboardDismissTapGesture!)
    }
}

然后添加:

func gestureRecognizer(gestureRecognizer: UIGestureRecognizer, shouldRecognizeSimultaneouslyWithGestureRecognizer otherGestureRecognizer: UIGestureRecognizer) -> Bool { 
    return true 
}

我的猜测是，您的表格 View 的手势干扰了新的 UITapGesture。试试这个解决方案，否则当检测到新的 UITapGesture 时，您的表格 View 的手势应该失败。

为了使 TableView 的 UITapGestureRecognizer 失败，我使用了以下代码:

if let recognizers = yourTableView.gestureRecognizers, let index = find(recognizers.map { $0 is UITapGestureRecognizer }, true) {
    (recognizers[index] as! UIPanGestureRecognizer).requireGestureRecognizerToFail(keyboardDismissTapGesture)
}

这可能不是最优雅的做法，但当我想让 UIPanGestureRecognizer 失败时，它对我有用。我还没有使用 UITapGestureRecognizer 对其进行测试。

编辑:

if let recognizers = yourTableView.gestureRecognizers, let index = find(recognizers.map { $0 is UIGestureRecognizer }, true) {
    (recognizers[index] as! UIGestureRecognizer).requireGestureRecognizerToFail(keyboardDismissTapGesture!)
}