NSNotification.Name.UIKeyboardWillShow 崩溃 - 无法找到原因

Question

我的应用程序的用户报告了随机崩溃。我已经集成了 CrashAnalytics，它提供了以下详细信息：

__CFNOTIFICATIONCENTER_IS_CALLING_OUT_TO_AN_OBSERVER__ + 20. 

表示的行号是154，即：

self.notesView.content.frame = CGRect(x: self.notesView.content.frame.origin.x, y: self.notesView.content.frame.origin.y, width: self.notesView.content.frame.size.width, height: self.notesView.content.frame.size.height - keyboardFrame.size.height). 

以下是我编写的代码，其中包含这一行：

override func viewWillAppear(_ animated: Bool) {
        super.viewWillAppear(animated)
        label_title.addObserver(self, forKeyPath: "contentSize", options: .new, context: nil)
        NotificationCenter.default.addObserver(self, selector: #selector(keyboardShown), name:NSNotification.Name.UIKeyboardWillShow, object: nil);
        NotificationCenter.default.addObserver(self, selector: #selector(keyboardHide), name:NSNotification.Name.UIKeyboardWillHide, object: nil);
    }

    override func viewWillDisappear(_ animated: Bool) {
        super.viewWillDisappear(animated)
        label_title.removeObserver(self, forKeyPath: "contentSize")
        NotificationCenter.default.removeObserver(self, name: NSNotification.Name.UIKeyboardWillShow, object: nil)
        NotificationCenter.default.removeObserver(self, name: NSNotification.Name.UIKeyboardWillHide, object: nil)
    }

    func keyboardShown(notification: NSNotification) {
        let info = notification.userInfo!
        let keyboardFrame: CGRect = (info[UIKeyboardFrameEndUserInfoKey] as! NSValue).cgRectValue
        self.notesView.content.frame = CGRect(x: self.notesView.content.frame.origin.x, y: self.notesView.content.frame.origin.y, width: self.notesView.content.frame.size.width, height: self.notesView.content.frame.size.height - keyboardFrame.size.height)
    }

首先，这是非常随机的，我从来没有得到它。其次，我无法找到它的确切原因。这是因为通知观察者还是因为 notesView（不是 nil）。
正如here 建议的那样，我应该在 deinit 中删除键盘通知观察器吗？
如果有人以前遇到过这种情况，请指导我。

Answer 1

把你的函数签名改成这个

@objc func keyboardShown(_ notification: Notification)