NSView無法觀察NSWindow變化 - KVO和Swift

Question

我很難讓我的NSView觀察其父母NSWindow中的更改。我在一個測試項目上嘗試了這個測試項目，僅僅包含一個NSWindow，其中包含MyView的子類NSView，只是爲了看看我是否缺少了一些東西。

class MyView: NSView { 

    //add observer on awake from nib 
    //works fine 
    override func awakeFromNib() { 
     if let win = self.window { 
      win.addObserver(self, forKeyPath: Notification.Name.NSWindowDidBecomeKey.rawValue, options: .new, context: nil) 
     } 
    } 

    //remove observer on dealloc 
    //allso works fine 
    deinit { 
     if let win = self.window { 
      win.removeObserver(self, forKeyPath: Notification.Name.NSWindowDidBecomeKey.rawValue) 
     } 
    } 

    //never gets called 
    override func observeValue(forKeyPath keyPath: String?, of object: Any?, change: [NSKeyValueChangeKey : Any]?, context: UnsafeMutableRawPointer?) { 
     Swift.print(keyPath ?? "") 
     Swift.print("worked!") 
    } 

    override func draw(_ dirtyRect: NSRect) { 
     NSColor.blue.set() 
     NSBezierPath.fill(dirtyRect) 
    } 
} 

我也嘗試了here的建議，但沒有運氣。我也檢查了其他答案並找不到答案。大多數封面製作您自己的類KVO兼容。我想觀察NSWindow對象。我錯過了什麼？

Answer 1

所以它看起來像NSWindowDidBecomeKey是Notification需要張貼到默認NotificationCenter而不是窗口本身。這是正確的代碼

class MyView: NSView { 

    //add observer on awake from nib 
    //works fine 
    override func awakeFromNib() { 
     if let win = self.window { 
      NotificationCenter.default.addObserver(self, selector: #selector(self.windowIsKey(_:)), name: .NSWindowDidBecomeKey, object: win) 
     } 
    } 

    //remove observer on dealloc 
    //allso works fine 
    deinit { 
     if let win = self.window { 
      NotificationCenter.default.removeObserver(self, name: .NSWindowDidBecomeKey, object: win) 
     } 
    } 

    //now this method is called and works fine 
    func windowIsKey(_ notification: Notification) { 
     Swift.print("worked!") 
    } 
}