/*
 以原图最短边为边长，居中裁剪 image 为正方形
 */
+ (UIImage *)centerClipImage:(UIImage *)image;

/*
 以原图最短边为边长，居中裁剪 image 为正方形
 */
+ (UIImage *)centerClipImage:(UIImage *)image
{
    if (!image) {
        return nil;
    }
    
    UIImage *srcImage = image;
    CGFloat val = 0.f;
    CGRect rect = CGRectZero;
    CGSize srcSize = srcImage.size;
    if ([@(srcSize.width) compare:@(srcSize.height)] == NSOrderedAscending) { // w < h
        val = srcSize.width;
        rect = CGRectMake(0.f, (srcSize.height - val) / 2.f, val, val);
    }
    else if ([@(srcSize.width) compare:@(srcSize.height)] == NSOrderedDescending) { // w > h
        val = srcSize.height;
        rect = CGRectMake((srcSize.width - val) / 2.f, 0.f, val, val);
    }
    else { // w = h
        return image;
    }
    
    CGImageRef cg = CGImageCreateWithImageInRect(srcImage.CGImage, rect);
    UIImage *clippedImage = [UIImage imageWithCGImage:cg];
    CGImageRelease(cg);
    
    return clippedImage;
}