cv::findContours( gray, contours, hierarchy, CV_RETR_EXTERNAL,
CV_CHAIN_APPROX_SIMPLE);
NSLog(@"contour size %lu",contours.size());
for (int i = 0; i< contours.size(); i++)
{
    cv::RotatedRect rect = cv::minAreaRect(contours[i]);
    cv::Point2f points[4];
    rect.points(points);

    std::vector<std::vector<cv::Point2f>> boxContours;

    cv::drawContours(image, boxContours, i,cvScalar(0,255,0),2);
}