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Realm provides many authentication providers to log users into your app. Each provider creates a unique user identity. Realm lets you merge multiple credentials into one user identity.
Credentials must be linked prior to logging a user in. Once credentials are used to login a user, you cannot link that credential anymore. Also, you cannot link multiple email/password credentials together.
Consider an application that offers anonymous login, which allows users to explore the app without
registering. If a user wants to continue using the application, they can create
a permanent account by using another authentication provider. Realm
creates a new
User object. The app can then link the new identity with the
Depending on how you have configured email/password authentication, there may be additional steps (confirming the email address, for example) before the new account is created and can be linked.