Roman Kerimov

Info.plist:
LSUIElement = YES

AppDelegate.swift:

import Cocoa

@NSApplicationMain
class AppDelegate: NSObject, NSApplicationDelegate {
    let statusMenu: NSMenu = .init()
    let statusItem = NSStatusBar.system.statusItem(withLength: NSStatusItem.squareLength)

    func applicationDidFinishLaunching(_ aNotification: Notification) {
        
        statusItem.button?.image = NSImage.init(named: NSImage.actionTemplateName)
        statusItem.menu = statusMenu
        
        let quitMenuItem: NSMenuItem = .init(title: "Quit", action: #selector(quit), keyEquivalent: "")
        statusMenu.addItem(quitMenuItem)
    }
    
    @objc func quit() {
        NSApp.terminate(self)
    }
}

Остальное как в курсах.