AVCaptureDevice.SystemPressureState

The performance and availability of the camera capture system on an iOS device is subject to several external factors, such as power usage and device temperature. If during a capture session the total system pressure reaches excessive levels, the capture system automatically shuts down, causing a session interruption (see AVCaptureSessionWasInterrupted). Under less heavy pressure, the system may automatically reduce capture quality.

To avoid such interruptions, use Key-value observing to monitor the capture device's systemPressureState property, and take action to reduce the performance impact of your capture session when system pressure increases—for example, by reducing the capture frame rate.