To get my feet wet with SwiftUI app development I’m making a simple app with login functionality using the AppAuth library. I’ve got basic login and logout functionality working and can make a request using the received access token. During refactoring to cleanup my code I’ve encountered a purple warning saying:

Publishing changes from background threads is not allowed; make sure to publish values from the main thread (via operators like receive(on:)) on model updates.

This is my simplified code:

@main
struct MyApp: App {
    @ObservedObject var authStore = AuthStore()

    var body: some Scene {
        WindowGroup {
            if authStore.isAuthenticated {
                MainView().environmentObject(authStore)
            } else {
                LoginView()
            }
        }
    }
}

class AuthStore: ObservableObject {
    @UIApplicationDelegateAdaptor(AppDelegate.self) var appDelegate

    private var authState : OIDAuthState?
    
    @Published var isAuthenticated = false // <- Xcode gives the warning for this line.

    func login() {
        // Prepare the necessary data like the authorization URL, clientID, etc. necessary for authentication
        self.appDelegate.currentAuthorizationFlow = OIDAuthState.authState(byPresenting: request, presenting: scene!.keyWindow!.rootViewController!) { authState, error in
            if let authState = authState {
                self.setAuthState(authState)
                print("Got authorization tokens. Access token: " +
                      "(authState.lastTokenResponse?.accessToken ?? "nil")")
            } else {
                print("Authorization error: (error?.localizedDescription ?? "Unknown error")")
                self.setAuthState(nil)
            }
        }
    }

    private func setAuthState(_ authState: OIDAuthState?) {
        if (self.authState == authState) {
            return;
        }
        
        self.authState = authState
        self.isAuthenticated = authState?.isAuthorized == true
    }
}

I’ve tried to annotate the AuthStore class with @MainActor, surround assigning a new value to the isAuthenticated variable with DispatchQueue.main.async { } and use .receive(on:) in the MyApp struct for the authStore.isAuthenticated usage. No matter what I tried the warning persists.

How can I resolve this warning?