iOS view模糊背景

/**
*  模糊背景
*
*  @param image    需要模糊的图片
*  @param blur     高斯模糊的值
*
*  @return
*/
- (UIImage *)blurryImage:(UIImage *)image withBlurLevel:(CGFloat)blur
{
if ((blur < 0.0f) || (blur > 1.0f)) {
blur = 0.5f;
}

int boxSize = (int)(blur * 100);
boxSize -= (boxSize % 2) + 1;

CGImageRef img = image.CGImage;

vImage_Buffer inBuffer, outBuffer;
vImage_Error error;
void *pixelBuffer;

CGDataProviderRef inProvider = CGImageGetDataProvider(img);
CFDataRef inBitmapData = CGDataProviderCopyData(inProvider);

inBuffer.width = CGImageGetWidth(img);
inBuffer.height = CGImageGetHeight(img);
inBuffer.rowBytes = CGImageGetBytesPerRow(img);
inBuffer.data = (void*)CFDataGetBytePtr(inBitmapData);

pixelBuffer = malloc(CGImageGetBytesPerRow(img) * CGImageGetHeight(img));

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);

CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
CGContextRef ctx = CGBitmapContextCreate(outBuffer.data, outBuffer.width, outBuffer.height, 8, outBuffer.rowBytes, colorSpace, CGImageGetBitmapInfo(image.CGImage));

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;
}