iOS 图片显示中遇到的压缩与裁剪问题

//裁剪图片  

- (UIImage *)cutImage:(UIImage*)image  

{  

    //压缩图片  

    CGSize newSize;  

    CGImageRef imageRef = nil;  

      

    if ((image.size.width / image.size.height) < (_headerView.bgImgView.size.width / _headerView.bgImgView.size.height)) {  

        newSize.width = image.size.width;  

        newSize.height = image.size.width * _headerView.bgImgView.size.height / _headerView.bgImgView.size.width;  

          

        imageRef = CGImageCreateWithImageInRect([image CGImage], CGRectMake(0, fabs(image.size.height - newSize.height) / 2, newSize.width, newSize.height));  

          

    } else {  

        newSize.height = image.size.height;  

        newSize.width = image.size.height * _headerView.bgImgView.size.width / _headerView.bgImgView.size.height;  

          

        imageRef = CGImageCreateWithImageInRect([image CGImage], CGRectMake(fabs(image.size.width - newSize.width) / 2, 0, newSize.width, newSize.height));  

  

    }  

  

    return [UIImage imageWithCGImage:imageRef];  

}