应用程序崩溃:异常 - 无法识别的选择器发送到实例 [英] App crashing: Exception - unrecognised selector sent to instance

问题描述

我有一个带有以下逻辑的 UITableviewController，一旦键盘像这样切换，就可以向上/向下滑动整个视图:

I've got a UITableviewController with following logic to slide up / down the entire view once the keyboard toggles like so:

class ChatDetailViewController: UIViewController, UITableViewDelegate, UITableViewDataSource {
 // variables...

 override func viewDidLoad() {
        super.viewDidLoad()
        // do stuff...
        NotificationCenter.default.addObserver(self, selector: Selector(("keyboardWillShow:")), name: UIResponder.keyboardWillShowNotification, object: nil)
        NotificationCenter.default.addObserver(self, selector: Selector(("keyboardWillHide:")), name: UIResponder.keyboardWillHideNotification, object: nil)
       // do other stuff...
}
...
func keyboardWillShow(notification: NSNotification) {
        if let keyboardSize = (notification.userInfo?[UIResponder.keyboardFrameBeginUserInfoKey] as? NSValue)?.cgRectValue {
            self.view.frame.origin.y -= keyboardSize.height
        }
    }

    func keyboardWillHide(notification: NSNotification) {
        self.view.frame.origin.y = 0
    }
...
}

切换键盘然后应用程序崩溃，出现以下异常:ChatDetailViewController keyboardWillShow:]: unrecognized selector sent to instance 0x7f82fc41fdf0

Toggling the keyboard then crashes the App with following exception: ChatDetailViewController keyboardWillShow:]: unrecognized selector sent to instance 0x7f82fc41fdf0

错误消息乍一看似乎很清楚，但我仍然无法弄清楚我的选择器出了什么问题.没有代码警告，没有错别字，...

The error message seems clear at first glance but I still can't figure out what's wrong with my selector. No code warnings, no typos,...

我在这里做错了什么?

推荐答案

三个问题:

• 选择器的创建有误(使用#selector)
• 动作的签名错误(缺少下划线)
• 动作必须标记为@objc

Swift 中的类型是 Notification 没有 NS 前缀

And the type in Swift is Notification without NS prefix

override func viewDidLoad() {
    super.viewDidLoad()
    // do stuff...
    NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillShow), name: UIResponder.keyboardWillShowNotification, object: nil)
    NotificationCenter.default.addObserver(self, selector: #selector(keyboardWillHide), name: UIResponder.keyboardWillHideNotification, object: nil)
    // do other stuff...
}

    ...

@objc func keyboardWillShow(_ notification: Notification) {
    if let keyboardSize = (notification.userInfo?[UIResponder.keyboardFrameBeginUserInfoKey] as? NSValue)?.cgRectValue {
        self.view.frame.origin.y -= keyboardSize.height
    }
}

@objc func keyboardWillHide(_ notification: Notification) {
    self.view.frame.origin.y = 0
}

...

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