---
title: currentUserDefinedAncillaryData
framework: AVFoundation
role: symbol
role_heading: Instance Property
platforms: [iOS 27.0+, iPadOS 27.0+, Mac Catalyst 27.0+, macOS 27.0+, tvOS 27.0+]
path: avfoundation/avcaptureancillarydataencoder/currentuserdefinedancillarydata
---

# currentUserDefinedAncillaryData

This is a representation of the user defined anacillary data.

## Declaration

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

## Discussion

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.  The dictionary will contain a NSUUID the rdd18InstanceUID key, a uint16_t for the rdd18UDAMSetVersion key and a dictionary for the rdd18UserItems. The 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 and rdd18UDAMSetVersion keys setRDD18AncillaryData(_:forTag:)  will update the rdd18UserItems key setRDD18AncillaryDataString(_:forTag:) will update the rdd18UserItems key