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# pictureInPictureController(_:didTransitionToRenderSize:)

Tells the delegate when the system Picture in Picture window changes size.

```
func pictureInPictureController(_ pictureInPictureController: AVPictureInPictureController, didTransitionToRenderSize newRenderSize: CMVideoDimensions)
```

## Parameters

`pictureInPictureController`

The Picture in Picture controller.

`newRenderSize`

The Picture in Picture content’s rendered size, in pixels.

## Discussion

Take the new render size and the [`isPictureInPictureActive`](/documentation/AVKit/AVPictureInPictureController/isPictureInPictureActive) state into account when choosing media variants to avoid uncessary decoding overhead.

---

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