试图知道当一个窗口在基于MacOS的文档应用

Question

我想知道当一个窗口关闭，我实现了这个代码将关闭：

class ViewController: NSViewController, NSWindowDelegate { 

    override func viewDidLoad() { 
     super.viewDidLoad() 

     let window: NSWindow? = view.window 
     window?.delegate = self 
    } 

    func windowWillClose(_ aNotification: Notification) { 
     print("windowWillClose") 
    } 

} 

可惜什么也没有发生，什么可能我做了错误的？

文件：https://developer.apple.com/documentation/appkit/nswindow/1419400-willclosenotification

PS 我已经看过这个问题没有找到一个解决办法：Handle close event of the window in Swift

Answer 1

的问题存在，窗口属性将总是返回零里面viewDidLoadMethod。您需要在viewWillAppear方法中设置代理：

class ViewController: NSViewController, NSWindowDelegate { 
    override func viewWillAppear() { 
     super.viewWillAppear() 
     view.window?.delegate = self 
    } 
    func windowWillClose(_ aNotification: Notification) { 
     print("windowWillClose") 
    } 
}