FAQ.md

Frequently Asked Questions

1. How can I disable the login alert box?
2. How can I disable the logout alert box?
3. How can I change the message in the alert box?
4. How can I programmatically close the alert box?

1. How can I disable the login alert box?

Under the hood, Auth0.swift uses ASWebAuthenticationSession by default to perform web-based authentication, which is the API provided by Apple for such purpose.

That alert box is displayed and managed by ASWebAuthenticationSession, not by Auth0.swift, because by default this API will store the session cookie in the shared Safari cookie jar. This makes single sign-on (SSO) possible. According to Apple, that requires user consent.

💡 See this blog post for a detailed overview of SSO on iOS.

If you don't need SSO, you can disable this behavior by adding useEphemeralSession() to the login call. This will configure ASWebAuthenticationSession to not store the session cookie in the shared cookie jar, as if using an incognito browser window. With no shared cookie, ASWebAuthenticationSession will not prompt the user for consent.

Auth0
    .webAuth()
    .useEphemeralSession() // No SSO, therefore no alert box
    .start { result in
        // ...
    }

Note that with useEphemeralSession() you don't need to call clearSession(federated:) at all. Just clearing the credentials from the app will suffice. What clearSession(federated:) does is clear the shared session cookie, so that in the next login call the user gets asked to log in again. But with useEphemeralSession() there will be no shared cookie to remove.

⚠️ useEphemeralSession() relies on the prefersEphemeralWebBrowserSession configuration option of ASWebAuthenticationSession. This option is only available on iOS 13+ and macOS, so useEphemeralSession() will have no effect on iOS 12. To improve the experience for iOS 12 users, see the approach described below.

An alternative is to use SFSafariViewController instead of ASWebAuthenticationSession. You can do so with the built-in SFSafariViewController Web Auth provider:

Auth0
    .webAuth()
    .provider(WebAuthentication.safariProvider()) // Use SFSafariViewController
    .start { result in
        // ...
    }

⚠️ Since SFSafariViewController does not share cookies with the Safari app, SSO will not work either. But it will keep its own cookies, so you can use it to perform SSO between your app and your website as long as you open it inside your app using SFSafariViewController. This also means that any feature that relies on the persistence of cookies will work as expected.

If you choose to use the SFSafariViewController Web Auth provider, you need to perform an additional bit of setup. Unlike ASWebAuthenticationSession, SFSafariViewController will not automatically capture the callback URL when Auth0 redirects back to your app, so it's necessary to manually resume the Web Auth operation.

Using the UIKit app lifecycle

// AppDelegate.swift

func application(_ app: UIApplication,
                 open url: URL,
                 options: [UIApplication.OpenURLOptionsKey: Any]) -> Bool {
    return WebAuthentication.resume(with: url)
}

Using the UIKit app lifecycle with Scenes

// SceneDelegate.swift

func scene(_ scene: UIScene, openURLContexts URLContexts: Set<UIOpenURLContext>) {
    guard let url = URLContexts.first?.url else { return }
    WebAuthentication.resume(with: url)
}

Using the SwiftUI app lifecycle

SomeView()
    .onOpenURL { url in
        WebAuthentication.resume(with: url)
    }

2. How can I disable the logout alert box?

If you need SSO and/or are willing to tolerate the alert box on the login call, but would prefer to get rid of it when calling clearSession(federated:), you can simply not call clearSession(federated:) and just clear the credentials from the app. This means that the shared session cookie will not be removed, so to get the user to log in again you need to add the "prompt": "login" parameter to the login call.

Auth0
    .webAuth()
    .useEphemeralSession()
    .parameters(["prompt": "login"]) // Ignore the cookie (if present) and show the login page
    .start { result in
        // ...
    }

Otherwise, the browser modal will close right away and the user will be automatically logged in again, as the cookie will still be there.

⚠️ Keeping the shared session cookie may not be an option if you have strong privacy and/or security requirements, for example in the case of a banking app.

3. How can I change the message in the alert box?

Auth0.swift has no control whatsoever over the alert box. Its contents cannot be changed. Unfortunately, that's a limitation of ASWebAuthenticationSession.

4. How can I programmatically close the alert box?

Auth0.swift has no control whatsoever over the alert box. It cannot be closed programmatically. Unfortunately, that's a limitation of ASWebAuthenticationSession.