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# fileOutput(_:didStartRecordingTo:from:)

Informs the delegate when the output has started writing to a file.

```
optional func fileOutput(_ output: AVCaptureFileOutput, didStartRecordingTo fileURL: URL, from connections: [AVCaptureConnection])
```

## Parameters

`output`

The capture file output that started writing the file.

`fileURL`

The file URL of the file that is being written.

`connections`

An array of [`AVCaptureConnection`](/documentation/AVFoundation/AVCaptureConnection) objects attached to the file output that provided the data that is being written to the file.

## Discussion

If an error condition prevents any data from being written, this method may not be called. [`fileOutput(_:willFinishRecordingTo:from:error:)`](/documentation/AVFoundation/AVCaptureFileOutputRecordingDelegate/fileOutput(_:willFinishRecordingTo:from:error:)) and [`fileOutput(_:didFinishRecordingTo:from:error:)`](/documentation/AVFoundation/AVCaptureFileOutputRecordingDelegate/fileOutput(_:didFinishRecordingTo:from:error:)) are always called, even if no data is written.

You should not assume that this method will be called on a specific thread, and should make this method as efficient as possible.

---

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