Property
The orientation of the receiver’s image. (read-only)
Discussion
Image orientation affects the way the image data is displayed when drawn. By default, images are displayed in the “up” orientation. If the image has associated metadata (such as EXIF information), however, this property contains the orientation indicated by that metadata. For a list of possible values for this property, see UIImageOrientation.

@interface UIImage (fixOrientation)
  
 - (UIImage *)fixOrientation;
  
 @end

@implementation UIImage (fixOrientation)
  
 - (UIImage *)fixOrientation {
  
     // No-op if the orientation is already correct
     if (self.imageOrientation == UIImageOrientationUp) return self;
  
     // We need to calculate the proper transformation to make the image upright.
     // We do it in 2 steps: Rotate if Left/Right/Down, and then flip if Mirrored.
     CGAffineTransform transform = CGAffineTransformIdentity;
  
     switch (self.imageOrientation) {
         case UIImageOrientationDown:
         case UIImageOrientationDownMirrored:
             transform = CGAffineTransformTranslate(transform, self.size.width, self.size.height);
             transform = CGAffineTransformRotate(transform, M_PI);
             break;
  
         case UIImageOrientationLeft:
         case UIImageOrientationLeftMirrored:
             transform = CGAffineTransformTranslate(transform, self.size.width, 0);
             transform = CGAffineTransformRotate(transform, M_PI_2);
             break;
  
         case UIImageOrientationRight:
         case UIImageOrientationRightMirrored:
             transform = CGAffineTransformTranslate(transform, 0, self.size.height);
             transform = CGAffineTransformRotate(transform, -M_PI_2);
             break;
         case UIImageOrientationUp:
         case UIImageOrientationUpMirrored:
             break;
     }
  
     switch (self.imageOrientation) {
         case UIImageOrientationUpMirrored:
         case UIImageOrientationDownMirrored:
             transform = CGAffineTransformTranslate(transform, self.size.width, 0);
             transform = CGAffineTransformScale(transform, -1, 1);
             break;
  
         case UIImageOrientationLeftMirrored:
         case UIImageOrientationRightMirrored:
             transform = CGAffineTransformTranslate(transform, self.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, self.size.width, self.size.height,
                                              CGImageGetBitsPerComponent(self.CGImage), 0,
                                              CGImageGetColorSpace(self.CGImage),
                                              CGImageGetBitmapInfo(self.CGImage));
     CGContextConcatCTM(ctx, transform);
     switch (self.imageOrientation) {
         case UIImageOrientationLeft:
         case UIImageOrientationLeftMirrored:
         case UIImageOrientationRight:
         case UIImageOrientationRightMirrored:
             // Grr...
             CGContextDrawImage(ctx, CGRectMake(0,0,self.size.height,self.size.width), self.CGImage);
             break;
  
         default:
             CGContextDrawImage(ctx, CGRectMake(0,0,self.size.width,self.size.height), self.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;
 }
  
 @end

func fixOrientationOfImage(image: UIImage) -> UIImage {
    // No-op if the orientation is already correct
    if image.imageOrientation == .Up
    {
        return image
    }
    // We need to calculate the proper transformation to make the image upright.
    // We do it in 2 steps: Rotate if Left/Right/Down, and then flip if Mirrored.
    var transform: CGAffineTransform = CGAffineTransformIdentity

    switch image.imageOrientation {
    case .Down:
    case .DownMirrored:
        transform = CGAffineTransformTranslate(transform, image..size.width, image..size.height)
        transform = CGAffineTransformRotate(transform, M_PI)
    case .Left:
    case .LeftMirrored:
        transform = CGAffineTransformTranslate(transform, image..size.width, 0)
        transform = CGAffineTransformRotate(transform, M_PI_2)
    case .Right:
    case .RightMirrored:
        transform = CGAffineTransformTranslate(transform, 0, image..size.height)
        transform = CGAffineTransformRotate(transform, -M_PI_2)
    case .Up:
    case .UpMirrored:
    }

    switch image.imageOrientation {
        switch image.imageOrientation {
        case .UpMirrored:
        case .DownMirrored:
            transform = CGAffineTransformTranslate(transform, image..size.width, 0)
            transform = CGAffineTransformScale(transform, -1, 1)
        case .LeftMirrored:
        case .RightMirrored:
            transform = CGAffineTransformTranslate(transform, image..size.height, 0)
            transform = CGAffineTransformScale(transform, -1, 1)
        case .Up:
        case .Down:
        case .Left:
        case .Right:
        }
    }

    // Now we draw the underlying CGImage into a new context, applying the transform
    // calculated above.
    var ctx: CGContextRef = CGBitmapContextCreate(nil, image..size.width, image..size.height, CGImageGetBitsPerComponent(image.CGImage), 0, CGImageGetColorSpace(image.CGImage), CGImageGetBitmapInfo(image.CGImage))
    CGContextConcatCTM(ctx, transform)

    switch image.imageOrientation {
    case .Left:
    case .LeftMirrored:
    case .Right:
    case .RightMirrored:
        // Grr...
        CGContextDrawImage(ctx, CGRectMake(0, 0, image..size.height, image..size.width), image.CGImage)
    default:
        CGContextDrawImage(ctx, CGRectMake(0, 0, image..size.width, image..size.height), image.CGImage)
    }

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

transform = CGAffineTransformRotate(transform, M_PI);

transform = CGAffineTransformTranslate(transform, self.size.width, self.size.height);

transform = CGAffineTransformTranslate(transform, self.size.width, self.size.height);
transform = CGAffineTransformRotate(transform, M_PI);

- (UIImage *)normalizedImage {
     if (self.imageOrientation == UIImageOrientationUp) return self; 
  
     UIGraphicsBeginImageContextWithOptions(self.size, NO, self.scale);
     [self drawInRect:(CGRect){0, 0, self.size}];
     UIImage *normalizedImage = UIGraphicsGetImageFromCurrentImageContext();
     UIGraphicsEndImageContext();
     return normalizedImage;
 }

-drawInRect:
Draws the entire image in the specified rectangle, scaling it as needed to fit.
Discussion
This method draws the entire image in the current graphics context, respecting the image’s orientation setting. In the default coordinate system, images are situated down and to the right of the origin of the specified rectangle. This method respects any transforms applied to the current graphics context, however.

(In Windows8)Explorer now respects EXIF orientation information for JPEG images. If your camera sets this value accurately, you will rarely need to correct orientation.