Is there a way not to show a window for a SwiftUI-lifecycle macOS app?

Question

I'm looking to not show a window for a SwiftUI application on macOS. The app uses SwiftUI's application lifecycle and only runs in the status bar. Showing a window on start up is unnecessary. I'm unsure however how to get around the WindowGroup. There's no such a thing as an EmptyScene and putting an EmptyView inside the WindowGroup of course creates an empty window.

@main
struct MyApp: App {
    @NSApplicationDelegateAdaptor(AppDelegate.self) var appDelegate

    var body: some Scene {
        WindowGroup {
            ContentView()
        }
    }
}

I basically only need the app delegate. I'm guessing using the default AppKit lifecycle makes more sense, but if there is a way to use SwiftUI's lifecycle, I'd love to know.

Answer 1

In your AppDelegate, do the following in your applicationDidFinishLaunching:

func applicationDidFinishLaunching(_ notification: Notification) {
    // Close main app window
    if let window = NSApplication.shared.windows.first {
        window.close()
    }
    
    // Code continues here...
}

For example:

class AppDelegate: NSObject, NSApplicationDelegate {
    var popover = NSPopover.init()
    var statusBar: StatusBarController?
    
    func applicationDidFinishLaunching(_ notification: Notification) {
        // Close main app window
        if let window = NSApplication.shared.windows.first {
            window.close()
        }
        
        // Create the SwiftUI view that provides the contents
        let contentView = ContentView()

        // Set the SwiftUI's ContentView to the Popover's ContentViewController
        popover.contentSize = NSSize(width: 160, height: 160)
        popover.contentViewController = NSHostingController(rootView: contentView)
        
        // Create the Status Bar Item with the above Popover
        statusBar = StatusBarController.init(popover)
    }
    
}