Keep track of versions? migrations?

How to keep track of the migrations, I mean, for release 1, we don’t have a list of objects that are already in realm, but for the next versions, we should keep a track of how the schema did update.

Do I need to have MyUserV1 and MyUserV2 MyUserV3 and so on?? or all could be inside MyUser?

How do you keep track of this to write the migrationBlock when opening the DB?