如何在NSMenu中放置水平滑块（Swift 3，Xcode 8）

从macOS Sierra开始，音量菜单栏项提供了一个水平滑块项来更改系统的音量：

我想在自己的应用程序中采用此概念，并提出了以下课程：

import Cocoa

@NSApplicationMain
class AppDelegate: NSObject, NSApplicationDelegate {

    @IBOutlet weak var window: NSWindow!
    let statusItem = NSStatusBar.system().statusItem(withLength: -2)

    func applicationDidFinishLaunching(_ aNotification: Notification) {

        let menu = NSMenu()
        let menuItem = NSMenuItem()
        let statusSlider = NSSlider()

        menu.addItem(NSMenuItem(title: "Slider:", action: nil, keyEquivalent: ""))

        menuItem.title = "Slider 1"
        menuItem.view = statusSlider
        menu.addItem(menuItem)

        menu.addItem(NSMenuItem.separator())

        menu.addItem(NSMenuItem(title: "Quit", action: Selector("terminate:"), keyEquivalent: "q"))

        statusItem.image = NSImage(named: "NSStatusAvailable")
        statusItem.menu = menu
    }
}

但是菜单中没有显示滑块。有人知道我做错了什么吗？