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[_headerImageView sd_setImageWithURL:[NSURL URLWithString:imageUrl] completed:^(UIImage *image, NSError *error, SDImageCacheType cacheType, NSURL *imageURL) {
           _headerImageView.image = [self boxblurImage:_headerImageView.image withBlurNumber:0.2];
    }];

-(UIImage *)boxblurImage:(UIImage *)image withBlurNumber:(CGFloat)blur
{
    if (!image) {
        image = IMAGENAMED(@"default_icon");
    }
    if (blur < 0.f || blur > 1.f) {
        blur = 0.2f;
    }
    int boxSize = (int)(blur * 40);
    boxSize = boxSize - (boxSize % 2) + 1;
    CGImageRef img = image.CGImage;
    vImage_Buffer inBuffer, outBuffer;
    vImage_Error error;
    void *pixelBuffer;
    //從CGImage中獲取數據
    CGDataProviderRef inProvider = CGImageGetDataProvider(img);
    CFDataRef inBitmapData = CGDataProviderCopyData(inProvider);
    //設置從CGImage獲取對象的屬性
    inBuffer.width = CGImageGetWidth(img);
    inBuffer.height = CGImageGetHeight(img);
    inBuffer.rowBytes = CGImageGetBytesPerRow(img);
    inBuffer.data = (void*)CFDataGetBytePtr(inBitmapData);
    pixelBuffer = malloc(CGImageGetBytesPerRow(img) * CGImageGetHeight(img));
    if(pixelBuffer == NULL)
        NSLog(@"No pixelbuffer");
    outBuffer.data = pixelBuffer;
    outBuffer.width = CGImageGetWidth(img);
    outBuffer.height = CGImageGetHeight(img);
    outBuffer.rowBytes = CGImageGetBytesPerRow(img);
    error = vImageBoxConvolve_ARGB8888(&inBuffer, &outBuffer, NULL, 0, 0, boxSize, boxSize, NULL, kvImageEdgeExtend);
    if (error) {
        NSLog(@"error from convolution %ld", error);
    }
    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
    CGContextRef ctx = CGBitmapContextCreate( outBuffer.data, outBuffer.width, outBuffer.height, 8, outBuffer.rowBytes, colorSpace, kCGImageAlphaNoneSkipLast);
    CGImageRef imageRef = CGBitmapContextCreateImage (ctx);
    UIImage *returnImage = [UIImage imageWithCGImage:imageRef];
    //clean up CGContextRelease(ctx);
    CGColorSpaceRelease(colorSpace);
    free(pixelBuffer);
    CFRelease(inBitmapData);
    CGColorSpaceRelease(colorSpace);
    CGImageRelease(imageRef);
    return returnImage;
}