string.length keypath 绑定在 Sonoma 上的 nib 解码期间崩溃

Question

从 macOS 14.0 收到一些崩溃报告。深入挖掘后，我发现问题与键路径绑定（

NSDisplayPatternValueBinding

）与

NSObjectController

和

NSTextView

有关。我将

NSTextView

绑定到 Storyboard 中的

NSObjectController

并在代码中设置

NSObjectController

的内容。内容是一个简单的

String

包装。

当我将 keypath 与“dot”（text.length）一起使用时，就会出现问题。如果我在从笔尖取消存档期间为已知的系统定义的文本替换（“在我的路上！”）设置字符串值 - 应用程序将崩溃并显示以下错误消息。但是，如果该值不在文本替换字典中，则不会崩溃。同样，对于简单的非点键路径，它也不会崩溃。如果我将模型对象更改为

NSString

，它不会崩溃

这是 macOS Sonoma 错误还是我以不应该的方式使用了绑定？

错误信息（异常断点）：

(lldb) po $x0
Cannot remove an observer <NSKeyValueObservance 0x6000031d0030> for the key path "length" from <Swift.__StringStorage 0x600002a7fa80> because it is not registered as an observer.
(null)

(lldb) po $x0
Cannot update for observer <NSObjectController 0x600000e78500> for the key path "text.length" from <KVOTextViewIssue.DymmyObject 0x600003f713a0>, most likely because the value for the key "text" has changed without an appropriate KVO notification being sent. Check the KVO-compliance of the KVOTextViewIssue.DymmyObject class.
(null)

Failed to set (contentViewController) user defined inspected property on (NSWindow): Cannot update for observer <NSObjectController 0x6000027f6620> for the key path "text.length" from <KVOTextViewIssue.DymmyObject 0x6000016be100>, most likely because the value for the key "text" has changed without an appropriate KVO notification being sent. Check the KVO-compliance of the KVOTextViewIssue.DymmyObject class.

最小可重现示例：

final class DymmyObject : NSObject {
    @objc dynamic var text : String = "On my way!" //CRASHES
    //@objc dynamic var text : NSString = "On my way!" //DOES NOT CRASH
    //@objc dynamic var text : String = "Hello" //DOES NOT CRASH
}

class ViewController: NSViewController {

    @IBOutlet var textView: NSTextView!
    @IBOutlet var objectController: NSObjectController! {
        didSet {
            representedObject = dummy
        }
    }
    var dummy : DymmyObject = DymmyObject()
    
    override func viewDidLoad() {
        super.viewDidLoad()
        self.textView.insertText("123", replacementRange: NSMakeRange(0, 0))
    }
}

深入挖掘 - 注意到崩溃时的后台线程是拼写检查器

Answer 1

将最低 macOS 部署目标从 10.13 提高到 10.14 解决了 Sonoma 上的崩溃/问题。