I'm moving an app from using CloudKit sync to using the Realm Mobile Platform.
I want the login process to be transparent to the user, so I'm using CloudKit authentication, this way they don't have to worry about creating an account or remembering a password. Of course if the user doesn't have an iCloud account set up, the data will not sync, but that's how the app is already working without realm: we just alert the user to the fact that the data will not sync because an iCloud account could not be found.
I noticed in the documentation that in order to open the synchronized realm, I have to provide the user's credentials.
My question is: how do I handle the case where the first time the user launches the app he doesn't have internet connection or doesn't have an iCloud account setup? I would like to just store the data locally if the user doesn't have an iCloud account (this is how the app works currently), but if I understand it correctly, the only way I can open the synchronized realm is to have the user's credentials, which I need internet access and an iCloud account to be set up on the device to get. Is there an easy way to handle that case with realm?
I know I could have a separate offline storage and move its data to the synced realm once on-line, but that would be tricky to get right and quite a bit of work.
Unfortunately you are correct: the very first time the user logs in to the Realm Object Server (via +[SyncUser logInWithCredentials:...]), the user needs to already have whatever identity provider account they're going to use (in your case, an iCloud account), as well as Internet connectivity.
Once the user's logged in at least once, their Realm credentials are persisted internally and the user can be used subsequently to open up Realms immediately, even if there is no connectivity.
The best workaround right now is to use a non-synced Realm to store whatever data you need before you have an opportunity to log in, and then manually copy the data over to your synchronized Realm once you are able to log in the user successfully and open the synced Realm with the user.
We know this is a pain point for a lot of our users, and plan to address this deficiency in the near future with features to let you immediately start using 'synced' Realms before a user has logged in.