Persist user logged in if the app restarts

[realm]

Persist user logged in if the app restarts

[am-MongoDB]

Hi @rubengarciam.

Custom user data is a useful feature but it has some limitations. On the Atlas side, it's a collection where each document is linked to a specific user. When a user authenticates in the frontend, the app gets a copy of the document as part of their user token. The frontend copy is read-only, and only gets updated to reflect Atlas when you re-login or after a period of time (30 minutes if I recall).

In O-FISH, the users are registered and setup by an administrator using a web app – so there's no need for the frontend app to modify the user data. That made custom data a good fit.

In RChat, the users register and setup their profile data in the frontend and so the read-only custom data option wouldn't work.

[am-MongoDB]

Hi @rubengarciam – that's a good question.

I've another Realm app that I think includes the behavior that you're looking for.

The top-level view checks if the user is already logged in, and if they are it continues as that user:

if settings.realmUser == nil && app.currentUser()?.state == .loggedIn {
    print("Using same user as when last running the app")
    settings.realmUser = app.currentUser()
}

It also uses face-id to store and retrieve the credentials in the keychain – see the app's LoginView:

...
if let error = self.keychain.addCredentials(Credentials(username: username, password: password)) as? KeychainError {
    print(error.localizedDescription)
}
...
private func getStoredCredentials() {
    let data = keychain.readCredentials()
    if let credentials = data.credentials {
        self.login(username: credentials.username, password: credentials.password)
    }

    if let error = data.error as? KeychainError {
        self.errorMessage = error.localizedDescription
    }
}

I hope this helps!

If you want to followup further, it would be great if you could create a topic on https://developer.mongodb.com/community/forums/c/realm/9 as it will get more eyeballs there – including from the SDK developers. Just tag me (@Andrew_Morgan) and add a link to your new topic to this issue.

[rubengarciam]

Thanks @am-MongoDB for sharing! After having a look at them I think that both have different data models and that raises some additional questions on my head, like why you are user a custom User object in RChat vs Realm.User in o-fish-ios? The former seems somewhat cleaner in my eyes, even though AppState and Settings serve a similar purpose.

Might be my lack of knowledge in the matter though. Happy to do some further reading if you can point me in the right direction.

I will create the topic in the community forum anyway.