Anonymous Authentication isn’t intended to persist data. If the user logs out, or the refresh token expires, the user can’t retrieve any previous user data. If you need to persist user data, you’ll want to register an account with a more permanent authentication method and then link the user identities. There’s an example of this on the Link User Identities page.
Ahh, I see. I’m not sure what exactly would happen if you tried to link every anonymous user to one user identifier, but I don’t think it’s possible. A better option might be to use a custom function to log in users, and then you can pass some arbitrary param - maybe a UUID for the user? - but not necessarily require a user-facing login.
Issue Fabricio is trying to solve is that one user is stuck with a bad token and he is not able to find a way to either clear that token and login again from that given device or refresh a token. iOS SDK for swift seems to be missing documentation about how and what method to call to refresh a token.