AVCaptureDevice *device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
if ([device hasTorch])
{
  [device lockForConfiguration:nil];
  //by these you can use Torch Flash Light..
  [device setTorchMode:AVCaptureTorchModeOn];  // use AVCaptureTorchModeOff to turn off
  [device unlockForConfiguration];
}