Get a CGAffineTransform from a UIInterfaceOrientation

gistfile1.m

#define DEGREES_TO_RADIANS(degrees) (degrees * M_PI / 180)

static CGAffineTransform transformForOrientation(UIInterfaceOrientation orientation)
{
    switch (orientation) {
        case UIInterfaceOrientationLandscapeLeft:
            return CGAffineTransformMakeRotation(DEGREES_TO_RADIANS(90));

        case UIInterfaceOrientationLandscapeRight:
            return CGAffineTransformMakeRotation(DEGREES_TO_RADIANS(-90));

        case UIInterfaceOrientationPortraitUpsideDown:
            return CGAffineTransformMakeRotation(DEGREES_TO_RADIANS(180));

        case UIInterfaceOrientationPortrait:
        default:
            return CGAffineTransformMakeRotation(DEGREES_TO_RADIANS(0));
    }
}