Crashing app at UIImageFromCVMat() in iOS

Here is the Code I have used to Convert CVMat to UIImage using OpenCV. With this Code everything works fine there is NO Crash in that. But Color gets changed.

    -(UIImage *)UIImageFromCVMat:(cv::Mat)cvMat
{
    cvtColor(cvMat, cvMat, CV_BGR2RGB);

    NSData *data = [NSData dataWithBytes:cvMat.data length:cvMat.elemSize()*cvMat.total()];
    CGColorSpaceRef colorSpace;

    if (cvMat.elemSize() == 1) {
        colorSpace = CGColorSpaceCreateDeviceGray();
    } else {
        colorSpace = CGColorSpaceCreateDeviceRGB();
    }

    CGDataProviderRef provider = CGDataProviderCreateWithCFData((__bridge CFDataRef)data);

    // Creating CGImage from cv::Mat
    CGImageRef imageRef = CGImageCreate(cvMat.cols,                                 //width
                                        cvMat.rows,                                 //height
                                        8,                                          //bits per component
                                        8 * cvMat.elemSize(),                       //bits per pixel
                                        cvMat.step[0],                            //bytesPerRow
                                        colorSpace,                                 //colorspace
                                        kCGImageAlphaNone|kCGBitmapByteOrderDefault,// bitmap info
                                        provider,                                   //CGDataProviderRef
                                        NULL,                                       //decode
                                        false,                                      //should interpolate
                                        kCGRenderingIntentDefault                   //intent
                                        );


    // Getting UIImage from CGImage
    UIImage *finalImage = [UIImage imageWithCGImage:imageRef];

    CGImageRelease(imageRef);
    CGDataProviderRelease(provider);
    CGColorSpaceRelease(colorSpace);

    return finalImage;
}

As a workaround I commented cvtColor() function from code. It is now able to retain original color but Now Issue is App is crashing randomly sometimes. I even tried to use UIImageFromCvMat() from opencv2/imgcodecs/ios.h but it crashes same way.

So if I want to prevent Crash I have to keep cvtColor() in code but it changes actual colors. Is there any mistake I have done here ?

EDIT

I just found that this is happening when I pass particular cvMat for UIImage Conversion in a method. I am posting my image processing code from where I am making call for Mat-->UIImage

It works fine when I pass grayImage (cvMat), but it crashes when I pass croppedImage (cvMat) for conversion.

    -(UIImage*)processImage:(UIImage*)sourceImage{

    cv::Mat processMat = [self cvMatFromUIImage:sourceImage];




    cv::Mat grayImage;
    cvtColor(processMat, grayImage, CV_BGR2GRAY);


    /// Generate grad_x and grad_y
    cv::Mat grad_x, grad_y;
    cv::Mat abs_grad_x, abs_grad_y;

    /// Gradient X
    //Scharr( src_gray, grad_x, ddepth, 1, 0, scale, delta, BORDER_DEFAULT );
    cv::Sobel( grayImage, grad_x, CV_16S, 1, 0, 3, 1 , 0);
    convertScaleAbs( grad_x, abs_grad_x );

    /// Gradient Y
    //Scharr( src_gray, grad_y, ddepth, 0, 1, scale, delta, BORDER_DEFAULT );
    Sobel( grayImage, grad_y, CV_16S, 0, 1, 3, 1, 0);
    convertScaleAbs( grad_y, abs_grad_y );

    // Total Gradient (approximate)
    cv::Mat grad;
    addWeighted( abs_grad_x, 0.5, abs_grad_y, 0.5, 0, grad );



    std::vector<std::vector<cv::Point> > contours;
    std::vector<cv::Vec4i> hierarchy;
    cv::findContours( grad, contours, hierarchy, cv::RETR_CCOMP, cv::CHAIN_APPROX_TC89_KCOS);

    double maxArea = 0;
    size_t maxIndex=0;
    for ( size_t i=0; i<contours.size(); ++i )
    {
                double area = cv::contourArea(contours[i]);
                if(area>maxArea){
                    maxIndex = i;
                    maxArea = area;
                }
    }

    cv::Rect brect = cv::boundingRect(contours[maxIndex]);
    cv::Mat croppedImage = processMat(brect);

    //It Works when I pass any other cvMat like grayImage
    //UIImage *result2 = [self UIImageFromCVMat:grayImage]; // MatToUIImage(grayImage);

    //This line causes Crash..
    UIImage *result = [self UIImageFromCVMat:croppedImage]; // MatToUIImage(grayImage);




    //Tried to Comment this part
    croppedImage.release();
    grad.release();
    grayImage.release();
    grad_x.release();
    grad_y.release();
    processMat.release();

    return result;
}

Convert mat from BGR2RGB and then RGB2BGR again, it will work. The reason behind this crash dont know, but trying this way is working. Add line cvtColor(cvMat, cvMat, CV_RGB2BGR) after cvtColor(cvMat, cvMat, CV_BGR2RGB);.