// 添加xml文件
NSString* cascadePath = [[NSBundle mainBundle]
                         pathForResource:@"haarcascade_frontalface_alt"
                         ofType:@"xml"];
faceDetector.load([cascadePath UTF8String]);


//上传图片 lena1    lenna
UIImage *image = [UIImage imageNamed:@"lena1"];
cv::Mat faceImage;
UIImageToMat(image, faceImage);

// 转为灰度
cv::Mat gray;
cvtColor(faceImage, gray, CV_BGR2GRAY);

// 检测人脸并储存
std::vector<cv::Rect>faces;
faceDetector.detectMultiScale(gray, faces,1.1,2,0|CV_HAAR_SCALE_IMAGE,cv::Size(30,30));

// 在每个人脸上画一个红色四方形
for(unsigned int i= 0;i < faces.size();i++)
{
    const cv::Rect& face = faces[i];
    cv::Point tl(face.x,face.y);
    cv::Point br = tl + cv::Point(face.width,face.height);
    
    // 四方形的画法
    cv::Scalar magenta = cv::Scalar(255, 0, 255);
    cv::rectangle(faceImage, tl, br, magenta, 4, 8, 0);
}

self.imageView.image = MatToUIImage(faceImage);