---
title: requiredSourceTrackIDs
framework: avfoundation
role: symbol
role_heading: Instance Property
path: avfoundation/avvideocompositioninstructionprotocol/requiredsourcetrackids
---

# requiredSourceTrackIDs

The identifiers of the video tracks the instruction requires to compose frames.

## Declaration

```swift
var requiredSourceTrackIDs: [NSValue]? { get }
```

## Discussion

Discussion If the value of this property is nil, the instruction requires all source tracks for composition.

## See Also

### Getting track ID settings

- [passthroughTrackID](avfoundation/avvideocompositioninstructionprotocol/passthroughtrackid.md)
- [requiredSourceSampleDataTrackIDs](avfoundation/avvideocompositioninstructionprotocol/requiredsourcesampledatatrackids.md)