SwiftUI: Change “About View” in macOS app

I am building a macOS-app using SwiftUI and the new App lifecycle.

I would love to change the contents of the “About Window” (that appears when you tap “About DemoApp” in the apps’ menu) but have no idea how:

How can I replace the About view with a custom one?

You can do it but it does require creating an AppDelegate. Here's what your AppFile should look like:

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

    var body: some Scene {
        WindowGroup {
            MainView()
        }
        .commands {
            CommandGroup(replacing: CommandGroupPlacement.appInfo) {
                Button(action: {
                    appDelegate.showAboutPanel()
                }) {
                    Text("About My App")
                }
            }
        }
    }
}

and your AppDelegate Should Look like this:

class AppDelegate: NSObject, NSApplicationDelegate {
    private var aboutBoxWindowController: NSWindowController?

    func showAboutPanel() {
        if aboutBoxWindowController == nil {
            let styleMask: NSWindow.StyleMask = [.closable, .miniaturizable,/* .resizable,*/ .titled]
            let window = NSWindow()
            window.styleMask = styleMask
            window.title = "About My App"
            window.contentView = NSHostingView(rootView: AboutView())
            aboutBoxWindowController = NSWindowController(window: window)
        }

        aboutBoxWindowController?.showWindow(aboutBoxWindowController?.window)
    }
}

Then, just make a SwiftUI View named AboutView and it'll display that in your About Box. For Example:

struct AboutView: View {
    var body: some View {
        VStack {
            Spacer()
            HStack {
                Spacer()
                Text("Hello, World!")
                Spacer()
            }
            Spacer()
        }
        .frame(minWidth: 300, minHeight: 300)
    }
}