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# begin(_:with:)

Sets up state information before the start of a given entity mapping.

```
func begin(_ mapping: NSEntityMapping, with manager: NSMigrationManager) throws
```

## Parameters

`mapping`

The mapping object in use.

`manager`

The migration manager performing the migration.

## Discussion

This method is the precursor to the creation stage. In a custom class, you can implement this method to set up any state information that will be useful for the duration of the migration.

## See Also

  [Core Data Model Versioning and Data Migration Programming Guide](https://developer.apple.com/library/archive/documentation/Cocoa/Conceptual/CoreDataVersioning/Articles/Introduction.html#//apple_ref/doc/uid/TP40004399)


---

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