- (void) turnTorchOn: (bool) on {

Class captureDeviceClass = NSClassFromString(@"AVCaptureDevice");
if (captureDeviceClass != nil) {
    AVCaptureDevice *device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
    if ([device hasTorch] && [device hasFlash]){

        [device lockForConfiguration:nil];
        if (on) {
            [device setTorchMode:AVCaptureTorchModeOn];
            [device setFlashMode:AVCaptureFlashModeOn];
            torchIsOn = YES;
        } else {
            [device setTorchMode:AVCaptureTorchModeOff];
            [device setFlashMode:AVCaptureFlashModeOff];
            torchIsOn = NO;            
        }
        [device unlockForConfiguration];
    }
}
}