Use the device's flash unit on iOS

Enabling the device's flash unit during an AR session can help improve visibility.

Check that the current camera configuration supports flash

Not all camera configurations support enabling a flash unit. Before enabling the flash or offering users the option to enable the flash, ensure that the flash unit is available for the active camera configuration:

AVCaptureDevice *device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
if (device) {
    return device.hasTorch;
}
return false;

Enable the flash unit

Enable the flash unit by configuring the AR session with AVCaptureTorchModeOn:

AVCaptureDevice *device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
if (device) {
    if (device.hasTorch) {
        NSError *error = nil;
        if ([device lockForConfiguration:&error]) {
            device.torchMode = AVCaptureTorchModeOn;
            [device unlockForConfiguration];
        } else {
            return;
        }
    }
}

Note: Configuring AVCaptureTorchModeOn with a camera configuration that does not support a flash unit will have no effect.

Disable the flash unit

Disable the flash unit by configuring the AR session with AVCaptureTorchModeOff:

AVCaptureDevice *device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
if (device) {
    if (device.hasTorch) {
        NSError *error = nil;
        if ([device lockForConfiguration:&error]) {
            device.torchMode = AVCaptureTorchModeOff;
            [device unlockForConfiguration];
        } else {
            return;
        }
    }
}