From the docs - https://developer.apple.com/documentation/authenticationservices/aswebauthenticationsession/2990952-init: callbackURLScheme The custom URL scheme that the app expects in the callback URL. Note custom URL scheme, which will allow ASWebAuthenticationSession to redirect back to your app and complete. If you need to redirect back to your app with an http(s) URL from an external user agent—that is, an authentication class like ASWebAuthenticationSession or a system browser—you'll need to do it on the OS level by using Universal Links - https://developer.apple.com/documentation/xcode/allowing_apps_and_websites_to_link_to_your_content. It's a big subject covered in the aforementioned doc and others referenced from there. In short, your redirection URI will point to a server where your apple-app-site-association file is hosted and a path specified for your app in this file. Then you'll need to handle the redirection in your app delegate's application(_:cont