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# init(source:version:)

Initializes a new source revision object with the provided source and version information.

```
init(source: HKSource, version: String?)
```

## Parameters

`source`

The source for a sample.

`version`

A string that uniquely identifies the source’s version.

## Return Value

A newly initialized source revision object.

## Discussion

Use this method to create source revisions for use in queries. For more information, see [`HKPredicateKeyPathSourceRevision`](/documentation/HealthKit/HKPredicateKeyPathSourceRevision).

On iOS 9.0 or later, the system automatically creates a source revision for any samples saved to the HealthKit store. For earlier versions of iOS, the system only saves [`HKSource`](/documentation/HealthKit/HKSource) information. However, when these samples are retrieved on iOS 9.0 or later, the system creates a new source revision object for the sample. HealthKit uses the previously stored source information with a `nil`-valued version string.

## See Also

[`HKSourceRevisionAnyVersion`](/documentation/HealthKit/HKSourceRevisionAnyVersion)

A constant that matches any version.


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