---
title: unusedTrackID()
framework: avfoundation
role: symbol
role_heading: Instance Method
path: avfoundation/avmutablemovie/unusedtrackid()
---

# unusedTrackID()

Returns an identifier that no other tracks in the asset use.

## Declaration

```swift
func unusedTrackID() -> CMPersistentTrackID
```

## Return Value

Return Value An unused CMPersistentTrackID value.

## See Also

### Accessing tracks

- [tracks](avfoundation/avmutablemovie/tracks.md)
- [track(withTrackID:)](avfoundation/avmutablemovie/track(withtrackid:).md)
- [tracks(withMediaType:)](avfoundation/avmutablemovie/tracks(withmediatype:).md)
- [tracks(withMediaCharacteristic:)](avfoundation/avmutablemovie/tracks(withmediacharacteristic:).md)