Make a Cocoa application quit when the main window is closed?

Question

How to make a Cocoa application quit when the main window is closed? Without that you have to click on the app icon and click quit in the menu.

Answer 1

This works for me.

extension MainWindowController: NSWindowDelegate {
    func windowWillClose(_ notification: Notification) {
        if let window = notification.object as? NSWindow, let controller = window.windowController {

            if window == self.window {

                for window in self.childWindows {

                    print(" Closing \(window)")
                    window.close()

                }

            }
        }
    }
}