---
title: isSubjectAreaChangeMonitoringEnabled
framework: avfoundation
role: symbol
role_heading: Instance Property
path: avfoundation/avcapturedevice/issubjectareachangemonitoringenabled
---

# isSubjectAreaChangeMonitoringEnabled

A Boolean value that indicates whether the device monitors the subject area for changes.

## Declaration

```swift
var isSubjectAreaChangeMonitoringEnabled: Bool { get set }
```

## Discussion

Discussion The value of this property indicates whether the device monitors the video subject area for changes, such as lighting changes, substantial movement, and so on. If you enable subject area change monitoring, the capture device object sends an subjectAreaDidChangeNotification whenever it detects a change to the subject area. You can observe this notification and take action such as focusing, adjusting exposure, and so on. Before changing the value of this property, you must call lockForConfiguration() to acquire exclusive access to the device’s configuration properties. Otherwise, setting the value of this property raises an exception. When you’re finished configuring the device, call unlockForConfiguration() to release the lock and allow other devices to configure the settings. This property is key-value observable.

## See Also

### Configuring camera hardware

- [lockForConfiguration()](avfoundation/avcapturedevice/lockforconfiguration().md)
- [unlockForConfiguration()](avfoundation/avcapturedevice/unlockforconfiguration().md)
- [subjectAreaDidChangeNotification](avfoundation/avcapturedevice/subjectareadidchangenotification.md)
- [Formats](avfoundation/capture-device-formats.md)
- [Focus](avfoundation/capture-device-focus.md)
- [Exposure](avfoundation/capture-device-exposure.md)
- [White balance](avfoundation/capture-device-white-balance.md)
- [Lighting](avfoundation/capture-device-lighting.md)
- [Color](avfoundation/capture-device-color.md)
- [Zoom](avfoundation/capture-device-zoom.md)