SwiftUI app showing how to prevent multiple `WindowGroup` windows

ContentView.swift

//
//  ContentView.swift
//  WindowExample
//
//  Created by Daniel Eden on 29/01/2024.
//

import SwiftUI

struct ContentView: View {
	@Environment(\.openWindow) var openWindow
    var body: some View {
			Button("Open `WindowGroup` window") {
				openWindow(id: "windowGroup", value: ScreenType.home)
			}
			
			Button("Open UUID window") {
				openWindow(value: UUID())
			}
    }
}

#Preview {
    ContentView()
}

WindowExample.swift

//
//  WindowExampleApp.swift
//  WindowExample
//
//  Created by Daniel Eden on 29/01/2024.
//

import SwiftUI

enum ScreenType: Codable {
	case home
}

@main
struct WindowExampleApp: App {
    var body: some Scene {
        WindowGroup {
            ContentView()
        }
			
			WindowGroup("Home Screen", id: "windowGroup", for: ScreenType.self) { screenType in
				Text("I'm part of a `WindowGroup`").foregroundStyle(.orange)
			} defaultValue: {
				.home
			}
			
			WindowGroup("uuid-example", for: UUID.self) { uuid in
				Text("I'm a unique window with a value of \(uuid.wrappedValue?.uuidString ?? "nil")").foregroundStyle(.teal)
			}
    }
}