NSMenuItem中的Swift 2.2选择器

import Cocoa

class StatusBarApp : NSObject {

  func buildMenu() {
    let statusItem = NSStatusBar.systemStatusBar().statusItemWithLength(NSVariableStatusItemLength)
    statusItem.title = "StatusBarApp"

    let menu = NSMenu()

    let aboutMenuItem = NSMenuItem()
    aboutMenuItem.title = "About"
    aboutMenuItem.target = self
    aboutMenuItem.action = #selector(about)
    menu.addItem(aboutMenuItem)

    statusItem.menu = menu
  }

  func about() {
    print("XXX")
  }
}

NSApplication.sharedApplication()
StatusBarApp().buildMenu()
NSApp.run()

我无法将“关于”菜单栏项连接到about()函数.当我运行应用程序时,“关于”项目被禁用.

如何将选择器传递给Swift 2.2中的菜单项操作？谢谢

aboutMenuItem.action = #selector(StatusBarApp.about(_:))

...

func about(sender : NSMenuItem) {
   print("XXX")
}

编辑：

解决方案是将应用程序作为完整的Cocoa应用程序运行,包括其委托.
我添加了第二个菜单项来终止应用程序.

import Cocoa

class StatusBarApp : NSObject, NSApplicationDelegate {

  var statusItem : NSStatusItem!

  func applicationDidFinishLaunching(aNotification: NSNotification) {
    statusItem = NSStatusBar.systemStatusBar().statusItemWithLength(NSVariableStatusItemLength)
    statusItem.title = "StatusBarApp"

    let menu = NSMenu()

    let aboutMenuItem = NSMenuItem(title:"About", action:#selector(StatusBarApp.about(_:)), keyEquivalent:"")
    aboutMenuItem.target = self
    let quitMenuItem = NSMenuItem(title:"Quit", action:#selector(StatusBarApp.quit(_:)), keyEquivalent:"")
    quitMenuItem.target = self
    menu.addItem(aboutMenuItem)
    menu.addItem(quitMenuItem)

    statusItem.menu = menu
  }

  func about(sender : NSMenuItem) {
    print("XXX")
  }

  func quit(sender : NSMenuItem) {
    NSApp.terminate(self)
  }
}

NSApplication.sharedApplication()
let statusBarApp = StatusBarApp()
NSApp.delegate = statusBarApp
NSApp.run()