NSMenu 未调用 validateMenuItem 或 menuWillOpen

我的 Mac 应用程序有一个 NSMenu，其委托功能validateMenuItem and menuWillOpen从来没有被调用过。到目前为止，网上的解决方案都没有帮助。

看来我做的一切都是对的：

• 菜单项的选择器属于同一类。
• 管理它的类继承自 NSMenuDelegate

我想描述我的问题的最好方法是发布相关代码。任何帮助，将不胜感激。

import Cocoa

class UIManager: NSObject, NSMenuDelegate {    
    var statusBarItem = NSStatusBar.system().statusItem(withLength: -2)
    var statusBarMenu = NSMenu()
    var titleMenuItem = NSMenuItem()
    var descriptionMenuItem = NSMenuItem()

    // ...

    override init() {            
        super.init()

        createStatusBarMenu()
    }

    // ...

    func createStatusBarMenu() {
        // Status bar icon
        guard let icon = NSImage(named: "iconFrame44")
            else { NSLog("Error setting status bar icon image."); return }
        icon.isTemplate = true
        statusBarItem.image = icon

        // Create Submenu items
        let viewOnRedditMenuItem = NSMenuItem(title: "View on Reddit...", action: #selector(viewOnRedditAction), keyEquivalent: "")
        let saveThisImageMenuItem = NSMenuItem(title: "Save This Image...", action: #selector(saveThisImageAction), keyEquivalent: "")

        // Add to title submenu
        let titleSubmenu = NSMenu(title: "")
        titleSubmenu.addItem(descriptionMenuItem)
        titleSubmenu.addItem(NSMenuItem.separator())
        titleSubmenu.addItem(viewOnRedditMenuItem)
        titleSubmenu.addItem(saveThisImageMenuItem)

        // Create main menu items
        titleMenuItem = NSMenuItem(title: "No Wallpaperer Image", action: nil, keyEquivalent: "")
        titleMenuItem.submenu = titleSubmenu
        getNewWallpaperMenuItem = NSMenuItem(title: "Update Now", action: #selector(getNewWallpaperAction), keyEquivalent: "")
        let preferencesMenuItem = NSMenuItem(title: "Preferences...", action: #selector(preferencesAction), keyEquivalent: "")
        let quitMenuItem = NSMenuItem(title: "Quit Wallpaperer", action: #selector(quitAction), keyEquivalent: "")

        // Add to main menu
        let statusBarMenu = NSMenu(title: "")
        statusBarMenu.addItem(titleMenuItem)
        statusBarMenu.addItem(NSMenuItem.separator())
        statusBarMenu.addItem(getNewWallpaperMenuItem)
        statusBarMenu.addItem(NSMenuItem.separator())
        statusBarMenu.addItem(preferencesMenuItem)
        statusBarMenu.addItem(quitMenuItem)

        statusBarItem.menu = statusBarMenu
    }

    // ...

    // Called whenever the menu is about to show. we use it to change the menu based on the current UI mode (offline/updating/etc)
    override func validateMenuItem(_ menuItem: NSMenuItem) -> Bool {
        NSLog("Validating menu item")
        if (menuItem == getNewWallpaperMenuItem) {
            if wallpaperUpdater!.state == .Busy {
                DispatchQueue.main.async {
                    self.getNewWallpaperMenuItem.title = "Updating Wallpaper..."
                }
                return false
            } else if wallpaperUpdater!.state == .Offline {
                DispatchQueue.main.async {
                    self.getNewWallpaperMenuItem.title = "No Internet Connection"
                }
                return false
            } else {
                DispatchQueue.main.async {
                    self.preferencesViewController.updateNowButton.title = "Update Now"
                }
                return true
            }
        }

        return true
    }

    // Whenever the menu is opened, we update the submitted time
    func menuWillOpen(_ menu: NSMenu) {
        NSLog("Menu will open")
        if !noWallpapererImageMode {
            DispatchQueue.main.async {
                self.descriptionMenuItem.title = "Submitted \(self.dateSimplifier(self.updateManager!.thisPost.attributes.created_utc as Date)) by \(self.updateManager!.thisPost.attributes.author) to /r/\(self.updateManager!.thisPost.attributes.subreddit)"
            }
        }
    }

    // ...

    // MARK: User-initiated actions

    func viewOnRedditAction() {
        guard let url = URL(string: "http://www.reddit.com\(updateManager!.thisPost.permalink)")
            else { NSLog("Could not convert post permalink to URL."); return }
        NSWorkspace.shared().open(url)
    }

    // Present a save panel to let the user save the current wallpaper
    func saveThisImageAction() {
        DispatchQueue.main.async {
            let savePanel = NSSavePanel()
            savePanel.makeKeyAndOrderFront(self)

            savePanel.nameFieldStringValue = self.updateManager!.thisPost.id + ".png"
            let result = savePanel.runModal()

            if result == NSFileHandlingPanelOKButton {
                let exportedFileURL = savePanel.url!
                guard let lastImagePath = UserDefaults.standard.string(forKey: "lastImagePath")
                    else { NSLog("Error getting last post ID from persistent storage."); return }
                let imageData = try! Data(contentsOf: URL(fileURLWithPath: lastImagePath))
                if (try? imageData.write(to: exportedFileURL, options: [.atomic])) == nil {
                    NSLog("Error saving image to user-specified folder.")
                }
            }
        }
    }

    func getNewWallpaperAction() {
        updateManager!.refreshAndReschedule(userInitiated: true)
    }

    func preferencesAction() {
        preferencesWindow.makeKeyAndOrderFront(nil)
        NSApp.activateIgnoringOtherApps(true)
    }

    func quitAction() {
        NSApplication.shared().terminate(self)
    }
}

menuWillOpen:属于NSMenuDelegate协议;要调用该菜单，需要一个委托：

let statusBarMenu = NSMenu(title: "")
statusBarMenu.delegate = self

validateMenuItem:属于NSMenuValidation非正式协议；以便将其称为相关菜单items必须有一个target。以下段落摘自Apple应用程序菜单和弹出列表编程主题 https://developer.apple.com/library/mac/documentation/Cocoa/Conceptual/MenuList/Articles/EnablingMenuItems.html文档：

当您使用自动菜单启用时，只要发生用户事件，NSMenu 就会更新每个菜单项的状态。要更新菜单项的状态，NSMenu 首先确定该项目的目标，然后确定该目标是否实现 validateMenuItem: 或 validateUserInterfaceItem:（按该顺序）。

let myMenuItem = NSMenuItem()
myMenuItem.target = self
myMenuItem.action = #selector(doSomething)