Question

if i draw my image I fixed the problem use CGAffintrasform

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);

when i wanna write to file
i use this

 NSData *imageData = UIImageJPEGRepresentation(backImage, 0);  

then Image upside down
how ?

Answer 1

When you want to get a UIImage to save, use:

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

Then do:

 NSData *imageData = UIImageJPEGRepresentation(backImage, 0);