iOS中对图片进行高斯模糊处理

- (UIImage *)GaussianBlurFrom:(UIImage *):image {
      CIContext *context = [CIContext contextWithOptions:nil];
      CIImage *image = [CIImage imageWithCGImage:image.CGImage];
      CIFilter *filter = [CIFilter filterWithName:@"CIGaussianBlur"];
      [filter setValue:image forKey:kCIInputImageKey];
      [filter setValue:@20.0f forKey:kCIInputRadiusKey];
      CIImage *result = [filter valueForKey:kCIOutputImageKey];
      CGRect extent = [result extent];
      return [UIImage imageWithCGImage:[context createCGImage:result fromRect:extent]];
    }