---
title: AVCaptureAncillaryDataUserKey
framework: AVFoundation
role: symbol
role_heading: Structure
platforms: [iOS 27.0+, iPadOS 27.0+, Mac Catalyst 27.0+, macOS 27.0+, tvOS 27.0+]
path: avfoundation/avcaptureancillarydatauserkey
---

# AVCaptureAncillaryDataUserKey

Clients may use an AVCaptureAncillaryDataUserKey to inspect the currentUserDefinedAncillaryData.

## Declaration

```swift
struct AVCaptureAncillaryDataUserKey
```

## Topics

### Creating a user key

- [init(rawValue:)](avfoundation/avcaptureancillarydatauserkey/init(rawvalue:).md)

### Type Properties

- [rdd18InstanceUID](avfoundation/avcaptureancillarydatauserkey/rdd18instanceuid.md)
- [rdd18UDAMSetVersion](avfoundation/avcaptureancillarydatauserkey/rdd18udamsetversion.md)
- [rdd18UserItems](avfoundation/avcaptureancillarydatauserkey/rdd18useritems.md)

## Relationships

### Conforms To

- [Equatable](swift/equatable.md)
- [Hashable](swift/hashable.md)
- [RawRepresentable](swift/rawrepresentable.md)
- [Sendable](swift/sendable.md)
- [SendableMetatype](swift/sendablemetatype.md)

## See Also

### Broadcast video output

- [AVCaptureBroadcastVideoOutput](avfoundation/avcapturebroadcastvideooutput.md)
- [AVCaptureBroadcastVideoOutputDelegate](avfoundation/avcapturebroadcastvideooutputdelegate.md)
- [AVCaptureAncillaryDataEncoder](avfoundation/avcaptureancillarydataencoder.md)