How to detect Escape key pressed in macOS apps?

if Int(event.keyCode) == kVK_Escape {
  print("Escape key pressed!")
}

NSEvent.addLocalMonitorForEvents(matching: .keyDown) {
  if self.keyDown(with: $0) {
    return nil // needed to get rid of purr sound
  } else {
    return $0
  }
}

private func keyDown(with event: NSEvent) -> Bool {
  if Int(event.keyCode) == kVK_Escape {
    print("Escape key pressed!")
    return true
  } else {
    return false
  }
}