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  "title" : "activeInputSource"
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# activeInputSource

The currently active input source of the device.

```
var activeInputSource: AVCaptureDevice.InputSource? { get set }
```

## Discussion

You must call [`lockForConfiguration()`](/documentation/AVFoundation/AVCaptureDevice/lockForConfiguration()) before attempting to set a format. Setting a format that isn’t present in the [`inputSources`](/documentation/AVFoundation/AVCaptureDevice/inputSources) array results in an exception.

This property is key-value observable.

---

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