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# currentUserDefinedAncillaryData

This is a representation of the user defined anacillary data.

```
var currentUserDefinedAncillaryData: [AVCaptureAncillaryDataUserKey : Any] { get }
```

## Discussion

Using SMPTE 291 and SMPTE RDD 18 standards for user-defined data, this property specifies the user-defined ancillary data to be sent with every frame in [`AVCaptureBroadcastVideoOutput`](/documentation/AVFoundation/AVCaptureBroadcastVideoOutput).  The dictionary will contain a NSUUID the [`rdd18InstanceUID`](/documentation/AVFoundation/AVCaptureAncillaryDataUserKey/rdd18InstanceUID) key, a uint16_t for the [`rdd18UDAMSetVersion`](/documentation/AVFoundation/AVCaptureAncillaryDataUserKey/rdd18UDAMSetVersion) key and a dictionary for the [`rdd18UserItems`](/documentation/AVFoundation/AVCaptureAncillaryDataUserKey/rdd18UserItems). The [`rdd18UserItems`](/documentation/AVFoundation/AVCaptureAncillaryDataUserKey/rdd18UserItems) will contain keys of the user tag and with the corresponding values.

To update the data please see the following methods:

- `setUserInstanceUID:userUdamVersion:` will update the [`rdd18InstanceUID`](/documentation/AVFoundation/AVCaptureAncillaryDataUserKey/rdd18InstanceUID) and [`rdd18UDAMSetVersion`](/documentation/AVFoundation/AVCaptureAncillaryDataUserKey/rdd18UDAMSetVersion) keys
- [`setRDD18AncillaryData(_:forTag:)`](/documentation/AVFoundation/AVCaptureAncillaryDataEncoder/setRDD18AncillaryData(_:forTag:))  will update the [`rdd18UserItems`](/documentation/AVFoundation/AVCaptureAncillaryDataUserKey/rdd18UserItems) key
- [`setRDD18AncillaryDataString(_:forTag:)`](/documentation/AVFoundation/AVCaptureAncillaryDataEncoder/setRDD18AncillaryDataString(_:forTag:)) will update the [`rdd18UserItems`](/documentation/AVFoundation/AVCaptureAncillaryDataUserKey/rdd18UserItems) key

---

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