试图了解基于 macOS 文档的应用程序中的窗口何时关闭

Question

我想知道窗口何时关闭，我实现了这段代码：

class ViewController: NSViewController, NSWindowDelegate {

    override func viewDidLoad() {
        super.viewDidLoad()

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

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

}

很遗憾，什么都没发生，我做错了什么？

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

PS 我已经阅读了这个问题但没有找到解决方案：Handle close event of the window in Swift

Answer 1

问题在于 window 属性在 viewDidLoadMethod 中总是返回 nil。您需要在 viewWillAppear 方法中设置委托：

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