生成一张高斯模糊的图片

/**

• 生成一张高斯模糊的图片
• @param image 原图
• @param blur 模糊程度 (0~1)
• @return 高斯模糊图片
  */

• (UIImage *)blurImage:(UIImage *)image blur:(CGFloat)blur;
  {
  if(image == nil ){
  return nil;
  }
  // 模糊度越界
  if (blur < 0.f || blur > 1.f) {
  blur = 0.5f;
  }
  int boxSize = (int)(blur * 150);
  boxSize = boxSize - (boxSize % 2) + 1;
  CGImageRef img = image.CGImage;
  vImage_Buffer inBuffer, outBuffer;
  vImage_Error error;
  void *pixelBuffer;
  //从CGImage中获取数据
  CGDataProviderRef inProvider = CGImageGetDataProvider(img);
  CFDataRef inBitmapData = CGDataProviderCopyData(inProvider);
  //设置从CGImage获取对象的属性
  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];

  CGContextRelease(ctx);
  CGColorSpaceRelease(colorSpace);

  free(pixelBuffer);
  CFRelease(inBitmapData);

  CGColorSpaceRelease(colorSpace);
  CGImageRelease(imageRef);

  return returnImage;
  }