IOS UIImage 图片颠倒

Question

如果我绘制我的图像，我会使用 CGAffintrasform 解决问题

CGAffineTransform myTr = CGAffineTransformMake(1, 0, 0, -1, 0, backImage.size.height);
CGContextConcatCTM(context, myTr);
[backImage drawInRect:CGRectMake(cbx, -cby, backImage.size.width, backImage.size.height)];
myTr = CGAffineTransformMake(1, 0, 0, -1, 0, backImage.size.height);
CGContextConcatCTM(context, myTr);

当我想写入文件时我用这个

 NSData *imageData = UIImageJPEGRepresentation(backImage, 0);  

然后图像颠倒怎么样？

Answer 1

当你想获取一个 UIImage 来保存时，使用:

UIGraphicsBeginImageContextWithOptions(size, isOpaque, 0);
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextDrawImage(context, (CGRect){ {0,0}, origSize }, [origImage CGImage]);
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return image;

然后做:

 NSData *imageData = UIImageJPEGRepresentation(backImage, 0);