Minimal Cocoa/AppKit Swift Package Manager application (SwiftPM)

main.swift

import AppKit

_ = NSApplication.shared
NSApp.setActivationPolicy(.regular)

//let delegate = AppDelegate()
//NSApplication.shared.delegate = delegate

let menubar = NSMenu()
let appMenuItem = NSMenuItem()
menubar.addItem(appMenuItem)

NSApp.mainMenu = menubar

let appMenu = NSMenu()
let appName = ProcessInfo.processInfo.processName

let quitTitle = "Quit \(appName)"

let quitMenuItem = NSMenuItem(title: quitTitle,
                              action: #selector(NSApplication.shared.terminate(_:)),
                              keyEquivalent: "q")
appMenu.addItem(quitMenuItem)
appMenuItem.submenu = appMenu

let window: NSWindow = NSWindow(contentRect: NSRect(x: 0, y: 0, width: 800, height: 600),
                                styleMask: [.titled, .closable, .miniaturizable, .resizable],
                                backing: .buffered,
                                defer: false)

window.center()
window.title = appName
window.makeKeyAndOrderFront(nil)
NSApp.activate(ignoringOtherApps: true)
NSApp.run()