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# AVExternalSyncDeviceDelegate

Defines an interface for delegates of [`AVCaptureDeviceInput`](/documentation/AVFoundation/AVCaptureDeviceInput) to respond to events that occur when connecting, calibrating, and disconnecting external sync devices.

```
protocol AVExternalSyncDeviceDelegate : NSObjectProtocol
```

## Topics

### Responding to device events

[`externalSyncDevice(_:failedWithError:)`](/documentation/AVFoundation/AVExternalSyncDeviceDelegate/externalSyncDevice(_:failedWithError:))

[`externalSyncDeviceStatusDidChange(_:)`](/documentation/AVFoundation/AVExternalSyncDeviceDelegate/externalSyncDeviceStatusDidChange(_:))

Informs your delegate when the external sync device status has changed.


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