FixRotation method for UIImage.

UIImage+fixBugs

- (UIImage *)fixRotation:(UIImage *)image
{
    if (image.imageOrientation == UIImageOrientationUp)
    {
            return image;
    }
    CGAffineTransform transform = CGAffineTransformIdentity;

    switch (image.imageOrientation)
    {
        case UIImageOrientationDown:
        case UIImageOrientationDownMirrored:
            transform = CGAffineTransformTranslate(transform, image.size.width, image.size.height);
            transform = CGAffineTransformRotate(transform, M_PI);
            break;

        case UIImageOrientationLeft:
        case UIImageOrientationLeftMirrored:
            transform = CGAffineTransformTranslate(transform, image.size.width, 0);
            transform = CGAffineTransformRotate(transform, M_PI_2);
            break;

        case UIImageOrientationRight:
        case UIImageOrientationRightMirrored:
            transform = CGAffineTransformTranslate(transform, 0, image.size.height);
            transform = CGAffineTransformRotate(transform, -M_PI_2);
            break;
        case UIImageOrientationUp:
        case UIImageOrientationUpMirrored:
            break;
    }

    switch (image.imageOrientation)
    {
        case UIImageOrientationUpMirrored:
        case UIImageOrientationDownMirrored:
            transform = CGAffineTransformTranslate(transform, image.size.width, 0);
            transform = CGAffineTransformScale(transform, -1, 1);
            break;

        case UIImageOrientationLeftMirrored:
        case UIImageOrientationRightMirrored:
            transform = CGAffineTransformTranslate(transform, image.size.height, 0);
            transform = CGAffineTransformScale(transform, -1, 1);
            break;
        case UIImageOrientationUp:
        case UIImageOrientationDown:
        case UIImageOrientationLeft:
        case UIImageOrientationRight:
            break;
    }

// Now we draw the underlying CGImage into a new context, applying the transform
// calculated above.
    CGContextRef ctx = CGBitmapContextCreate(NULL, image.size.width, image.size.height,
            CGImageGetBitsPerComponent(image.CGImage), 0,
            CGImageGetColorSpace(image.CGImage),
            CGImageGetBitmapInfo(image.CGImage));
    CGContextConcatCTM(ctx, transform);
    switch (image.imageOrientation)
    {
        case UIImageOrientationLeft:
        case UIImageOrientationLeftMirrored:
        case UIImageOrientationRight:
        case UIImageOrientationRightMirrored:
            // Grr...
            CGContextDrawImage(ctx, CGRectMake(0, 0, image.size.height, image.size.width), image.CGImage);
            break;

        default:
            CGContextDrawImage(ctx, CGRectMake(0, 0, image.size.width, image.size.height), image.CGImage);
            break;
    }

// And now we just create a new UIImage from the drawing context
    CGImageRef cgimg = CGBitmapContextCreateImage(ctx);
    UIImage *img = [UIImage imageWithCGImage:cgimg];
    CGContextRelease(ctx);
    CGImageRelease(cgimg);
    return img;
}