public class Update: ObservableObject, Fetchable

init(Option)

import Update

class SceneDelegate: UIResponder, UIWindowSceneDelegate {

    var window: UIWindow?

    func scene(
        _ scene: UIScene,
        willConnectTo session: UISceneSession,
        options connectionOptions: UIScene.ConnectionOptions
    ) {

        if let windowScene = scene as? UIWindowScene {
            
            let window = UIWindow(windowScene: windowScene)
            let contentView = ContentView()
            let update = Update(.available)

            window.rootViewController = UIHostingController(rootView: contentView
                .environmentObject(update)
            )
            self.window = window
            window.makeKeyAndVisible()
        }
    }
}

import Update

struct ContentView: View {
    
    @EnvironmentObject private var update: Update
    
    var body: some View {

        return EmptyView()
        .onAppear(perform: {
            
            self.update.fetch(from: Itunes.lookupURL)
        })
        .alert(isPresented: self.$update.showingAlert) { self.update.alert! }
    }
}