I'm trying since 5 hours now:

- (void)drawRect:(CGRect)rect {
    // flip the wrong coordinate system
    CGContextTranslateCTM(context, 0.0f, rect.size.height); //shift the origin up
    CGContextScaleCTM(context, 1.0f, -1.0f); //flip the y-axis

    CGContextDrawImage(context, myImgView.frame, myImageView.image.CGImage);
}

The problem: While the image draws correctly, the coordinates specified by the UIImageView frame are completely useless. The image appears placed completely wrong on screen.

I guess I must also flip the CGRect of the UIImageView? But how?