如何跟踪NSWindow的开闭事件？

class MyWindowDelegate: NSObject, NSWindowDelegate {
    func windowWillOpen(_ notification: Notification) {
        // 窗口即将打开时的操作
    }
    
    func windowDidOpen(_ notification: Notification) {
        // 窗口已经打开时的操作
    }
    
    func windowWillClose(_ notification: Notification) {
        // 窗口即将关闭时的操作
    }
    
    func windowDidClose(_ notification: Notification) {
        // 窗口已经关闭时的操作
    }
}

// 创建窗口
let window = NSWindow(contentRect: NSRect(x: 0, y: 0, width: 800, height: 600), styleMask: [.titled, .closable, .resizable], backing: .buffered, defer: false)

// 设置窗口代理
let windowDelegate = MyWindowDelegate()
window.delegate = windowDelegate