This is now possible in Realm Cloud. Here's how I am doing it in Swift:
if let user = SyncUser.current {
//--== User available ==--
let config = Realm.Configuration(syncConfiguration: SyncConfiguration(user: user, realmURL: "..."))
Realm.Configuration.defaultConfiguration = config
let _ = try! Realm()
}else{
//--== No User; Connect Anonymously ==--
let credentials = SyncCredentials.anonymous()
SyncUser.logIn(with: credentials, server: "...") { user, error in
DispatchQueue.main.async {
if let user = user {
let config = Realm.Configuration(syncConfiguration: SyncConfiguration(user: user, realmURL: "..."))
Realm.Configuration.defaultConfiguration = config
let _ = try! Realm()
}else{
//Error...
}
}
}
}
}
Good luck!