---
title: "transitionToItem(withIdentifier:proposingInitialTimingBasedOn:)"
framework: avfoundation
role: symbol
role_heading: Instance Method
path: "avfoundation/avdelegatingplaybackcoordinator/transitiontoitem(withidentifier:proposinginitialtimingbasedon:)"
---

# transitionToItem(withIdentifier:proposingInitialTimingBasedOn:)

Tells the coordinator to transition to a new item.

## Declaration

```swift
func transitionToItem(withIdentifier itemIdentifier: String?, proposingInitialTimingBasedOn snapshotTimebase: CMTimebase?)
```

## Parameters

- `itemIdentifier`: The identifier for the new current item, which is nil if there isn’t anything to play.
- `snapshotTimebase`: A time base that communicates the initial playback state of the new item. If you specify nil, the coordinator assumes that the player pauses at doc://com.apple.documentation/documentation/CoreMedia/CMTime/zero. You can retrieve an appropriate time base to pass for this value from AVFoundation playback objects like doc://com.apple.avfoundation/documentation/AVFoundation/AVSampleBufferRenderSynchronizer. You can also create one manually using the doc://com.apple.documentation/documentation/CoreMedia/CMTimebaseCreateWithSourceClock(allocator:sourceClock:timebaseOut:) function.

## See Also

### Coordinating state changes

- [coordinateRateChange(to:options:)](avfoundation/avdelegatingplaybackcoordinator/coordinateratechange(to:options:).md)
- [coordinateSeek(to:options:)](avfoundation/avdelegatingplaybackcoordinator/coordinateseek(to:options:).md)
- [reapplyCurrentItemStateToPlaybackControlDelegate()](avfoundation/avdelegatingplaybackcoordinator/reapplycurrentitemstatetoplaybackcontroldelegate().md)
- [AVDelegatingPlaybackCoordinatorSeekOptions](avfoundation/avdelegatingplaybackcoordinatorseekoptions.md)
- [AVDelegatingPlaybackCoordinatorRateChangeOptions](avfoundation/avdelegatingplaybackcoordinatorratechangeoptions.md)