In order to handle manual migrations, you need to supply a migration callback to your
RealmConfiguration. It will be called with a Migration instance containing
the pre- and the post-migration Realm. You should make sure that the NewRealm
property on it contains a database that is up to date when returning. The
parameter will tell you which SchemaVersion the user is migrating
from. They should always be migrating to the current SchemaVersion.
public delegate void MigrationCallbackDelegate(Migration migration, ulong oldSchemaVersion);