swift osx application without nib

app.swift

import Cocoa


class WindowController: NSWindowController {
}

class AppDelegate: NSObject {
  var mainWindow: NSWindow?
  var mainController: NSWindowController?
}

extension AppDelegate {
  @objc func quit(sender: NSMenuItem) {
    NSApp.terminate(self)
  }
}

extension AppDelegate: NSApplicationDelegate {
  func applicationDidFinishLaunching(_ aNotification: Notification) {
    let mainMenu = NSMenu()
    let mainMenuFileItem = NSMenuItem(title: "File", action: nil, keyEquivalent: "")
    let fileMenu = NSMenu(title: "File")
    fileMenu.addItem(withTitle: "Quit", action: #selector(quit(sender:)), keyEquivalent: "q")
    mainMenuFileItem.submenu = fileMenu
    mainMenu.addItem(mainMenuFileItem)
    NSApp.mainMenu = mainMenu

    let window = NSWindow(contentRect: NSMakeRect(1280, 960, 1280, 960), styleMask:[.titled, .closable, .resizable], backing: .buffered, defer: false)
    window.backgroundColor = NSColor(calibratedRed: 0.1, green: 0.1, blue: 0.1, alpha: 1.0)
    window.title = "App"
    window.orderFrontRegardless()
    mainWindow = window

    let controller = WindowController(window: window)
    controller.showWindow(window)
    mainController = controller

    NSApp.activate(ignoringOtherApps: true)
  }

  func applicationWillTerminate(_ aNotification: Notification) {
  }

  func applicationShouldTerminateAfterLastWindowClosed(_ app: NSApplication) -> Bool{
    return true
  }
}

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

app.setActivationPolicy(.regular)
atexit_b { app.setActivationPolicy(.prohibited); return }
app.run()

osx-nibless

.PHONY: build

build:
	@DEVELOPER_DIR="/Applications/Xcode.app" SDKROOT="/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk" xcrun swiftc -o app app.swift && ./app

WindowController what is this?