macOS how to have nswindow vibrant title bar on swift 3

[abcdefg12345]

I'm trying to have a window full translucent window but my code is not working anyone know where i went wrong

@IBOutlet weak var visualeffect: NSVisualEffectView!

    func applicationDidFinishLaunching(_ aNotification: Notification) {
        visualeffect.blendingMode = NSVisualEffectBlendingMode.behindWindow
        visualeffect.material = NSVisualEffectMaterial.dark
        self.window.contentView?.addSubview(visualeffect)
        self.window.styleMask = NSWindowStyleMask.fullSizeContentView
        self.window.appearance = NSAppearance.init(named: NSAppearanceNameVibrantDark)
    }

 

[KALLT]

What is not working?