---
title: AVMutableCompositionTrack
framework: avfoundation
role: symbol
role_heading: Class
path: avfoundation/avmutablecompositiontrack
---

# AVMutableCompositionTrack

A mutable track in a composition that you use to insert, remove, and scale track segments without affecting their low-level representation.

## Declaration

```swift
class AVMutableCompositionTrack
```

## Overview

Overview Use this object to define constraints for the temporal arrangement of the track segments. If you set the composition’s track segments, you can test whether they meet the constraints by calling the validateSegments(_:) method.

## Topics

### Configuring track properties

- [isEnabled](avfoundation/avmutablecompositiontrack/isenabled.md)
- [naturalTimeScale](avfoundation/avmutablecompositiontrack/naturaltimescale.md)
- [languageCode](avfoundation/avmutablecompositiontrack/languagecode.md)
- [extendedLanguageTag](avfoundation/avmutablecompositiontrack/extendedlanguagetag.md)
- [preferredTransform](avfoundation/avmutablecompositiontrack/preferredtransform.md)
- [preferredVolume](avfoundation/avmutablecompositiontrack/preferredvolume.md)

### Managing time ranges

- [segments](avfoundation/avmutablecompositiontrack/segments.md)
- [insertEmptyTimeRange(_:)](avfoundation/avmutablecompositiontrack/insertemptytimerange(_:).md)
- [insertTimeRange(_:of:at:)](avfoundation/avmutablecompositiontrack/inserttimerange(_:of:at:).md)
- [insertTimeRanges(_:of:at:)](avfoundation/avmutablecompositiontrack/inserttimeranges(_:of:at:).md)
- [removeTimeRange(_:)](avfoundation/avmutablecompositiontrack/removetimerange(_:).md)
- [scaleTimeRange(_:toDuration:)](avfoundation/avmutablecompositiontrack/scaletimerange(_:toduration:).md)

### Associating tracks

- [addTrackAssociation(to:type:)](avfoundation/avmutablecompositiontrack/addtrackassociation(to:type:).md)
- [removeTrackAssociation(to:type:)](avfoundation/avmutablecompositiontrack/removetrackassociation(to:type:).md)

### Replacing format descriptions

- [replaceFormatDescription(_:with:)](avfoundation/avmutablecompositiontrack/replaceformatdescription(_:with:).md)

### Validating segments

- [validateSegments(_:)](avfoundation/avmutablecompositiontrack/validatesegments(_:).md)

## Relationships

### Inherits From

- [AVCompositionTrack](avfoundation/avcompositiontrack.md)

### Conforms To

- [AVAsynchronousKeyValueLoading](avfoundation/avasynchronouskeyvalueloading.md)
- [CVarArg](swift/cvararg.md)
- [CustomDebugStringConvertible](swift/customdebugstringconvertible.md)
- [CustomStringConvertible](swift/customstringconvertible.md)
- [Equatable](swift/equatable.md)
- [Hashable](swift/hashable.md)
- [NSCopying](foundation/nscopying.md)
- [NSObjectProtocol](objectivec/nsobjectprotocol.md)

## See Also

### Mutable compositions

- [AVMutableComposition](avfoundation/avmutablecomposition.md)