The documentation states that you can use either finishDeferredLightweightMigrationTask or finishDeferredLightweightMigration to complete a deferred migration at a later time. However when I tried finishDeferredLightweightMigrationTask, I noticed that the metadata for the store isn't updated. How would you know when the migration has completed and you can stop calling finishDeferredLightweightMigrationTask?
The reason I was reaching for the individual migration task approach is that I thought it would be better for handling an expired background task since I could check for cancellation after each step.