<!--
{
  "availability" : [
    "iOS: -",
    "iPadOS: -",
    "macCatalyst: -",
    "macOS: -",
    "tvOS: -",
    "visionOS: -",
    "watchOS: -"
  ],
  "documentType" : "symbol",
  "framework" : "AVFoundation",
  "identifier" : "/documentation/AVFoundation/AVAssetTrack/AssociationType",
  "metadataVersion" : "0.1.0",
  "role" : "Structure",
  "symbol" : {
    "kind" : "Structure",
    "modules" : [
      "AVFoundation"
    ],
    "preciseIdentifier" : "c:@T@AVTrackAssociationType"
  },
  "title" : "AVAssetTrack.AssociationType"
}
-->

# AVAssetTrack.AssociationType

Constants that define track association types.

```
struct AssociationType
```

## Topics

### Track association types

[`audioFallback`](/documentation/AVFoundation/AVAssetTrack/AssociationType/audioFallback)

The track contains the same content as another track, but in a more widely supported format.

[`chapterList`](/documentation/AVFoundation/AVAssetTrack/AssociationType/chapterList)

The associated track contains chapter information for the base track.

[`forcedSubtitlesOnly`](/documentation/AVFoundation/AVAssetTrack/AssociationType/forcedSubtitlesOnly)

An association between a subtitle track containing forced and nonforced subtitles and one with a subtitle track containing only forced subtitles.

[`metadataReferent`](/documentation/AVFoundation/AVAssetTrack/AssociationType/metadataReferent)

An association between a metadata track and the track that it describes or annotates.

[`selectionFollower`](/documentation/AVFoundation/AVAssetTrack/AssociationType/selectionFollower)

An association between two tracks that specifies when a user selects the main track, the system should follow that selection by automatically selecting the associated track.

[`timecode`](/documentation/AVFoundation/AVAssetTrack/AssociationType/timecode)

An association between a timecode track providing timing information for the main track.

[`renderMetadataSource`](/documentation/AVFoundation/AVAssetTrack/AssociationType/renderMetadataSource)

Indicates an association between a metadata track and another track where the metadata provides additional information for rendering of that track.

### Initializers

[`init(rawValue:)`](/documentation/AVFoundation/AVAssetTrack/AssociationType/init(rawValue:))

Creates an association type with a string value.


---

Copyright &copy; 2026 Apple Inc. All rights reserved. | [Terms of Use](https://www.apple.com/legal/internet-services/terms/site.html) | [Privacy Policy](https://www.apple.com/privacy/privacy-policy)