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# NSUUIDChangedPersistentStoresKey

Key for an array containing the old and new stores.

```
let NSUUIDChangedPersistentStoresKey: String
```

## Discussion

The object at index `0` is the old store instance, and the object at index `1` the new. When migration happens, the array contains a third object (at index `2`) that is an array containing the new objectIDs for all the migrated objects.

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