Extension to fix orientation of an UIImage (Sets orientation to portrait)

UIImageFixedOrientationExtension.swift

extension UIImage {

    func fixedOrientation() -> UIImage {
        
        if imageOrientation == UIImageOrientation.Up {
            return self
        }
        
        var transform: CGAffineTransform = CGAffineTransformIdentity
        
        switch imageOrientation {
        case UIImageOrientation.Down, UIImageOrientation.DownMirrored:
            transform = CGAffineTransformTranslate(transform, size.width, size.height)
            transform = CGAffineTransformRotate(transform, CGFloat(M_PI))
            break
        case UIImageOrientation.Left, UIImageOrientation.LeftMirrored:
            transform = CGAffineTransformTranslate(transform, size.width, 0)
            transform = CGAffineTransformRotate(transform, CGFloat(M_PI_2))
            break
        case UIImageOrientation.Right, UIImageOrientation.RightMirrored:
            transform = CGAffineTransformTranslate(transform, 0, size.height)
            transform = CGAffineTransformRotate(transform, CGFloat(-M_PI_2))
            break
        case UIImageOrientation.Up, UIImageOrientation.UpMirrored:
            break
        }
        
        switch imageOrientation {
        case UIImageOrientation.UpMirrored, UIImageOrientation.DownMirrored:
            CGAffineTransformTranslate(transform, size.width, 0)
            CGAffineTransformScale(transform, -1, 1)
            break
        case UIImageOrientation.LeftMirrored, UIImageOrientation.RightMirrored:
            CGAffineTransformTranslate(transform, size.height, 0)
            CGAffineTransformScale(transform, -1, 1)
        case UIImageOrientation.Up, UIImageOrientation.Down, UIImageOrientation.Left, UIImageOrientation.Right:
            break
        }
        
        let ctx: CGContextRef = CGBitmapContextCreate(nil, Int(size.width), Int(size.height), CGImageGetBitsPerComponent(CGImage), 0, CGImageGetColorSpace(CGImage), CGImageAlphaInfo.PremultipliedLast.rawValue)!
        
        CGContextConcatCTM(ctx, transform)
        
        switch imageOrientation {
        case UIImageOrientation.Left, UIImageOrientation.LeftMirrored, UIImageOrientation.Right, UIImageOrientation.RightMirrored:
            CGContextDrawImage(ctx, CGRectMake(0, 0, size.height, size.width), CGImage)
            break
        default:
            CGContextDrawImage(ctx, CGRectMake(0, 0, size.width, size.height), CGImage)
            break
        }
        
        let cgImage: CGImageRef = CGBitmapContextCreateImage(ctx)!
        
        return UIImage(CGImage: cgImage)
    }
}

Could someone explain me why we need transform.translatedBy?

Wouldn't only .rotated(by... and .scaledBy(... (for flipped images) do it? 🤔

I believe those transform around the origin (0, 0) and would thus flip/rotate your image to be outside the box. if you try it with an angle of around 45° you’ll see how it would break.

I believe those transform around the origin (0, 0) and would thus flip/rotate your image to be outside the box. if you try it with an angle of around 45° you’ll see how it would break.

Thanks!

Hi, here's my solution. It relies on iOS's UIImage handing of the orientation. So an "xyz" orientated image is rendered (using it's orientation info) onto an up orientated canvas.

⚠️ self.draw of UIImage, not CGImage.

extension UIImage
{
    /// `Re-orientate` the image to `up`.
    ///
    func normalizedImage() -> UIImage?
    {
        if self.imageOrientation == .up
        {
            return self
        }
        else
        {
            UIGraphicsBeginImageContextWithOptions(self.size, false, self.scale)
            defer
            {
                UIGraphicsEndImageContext()
            }

            self.draw(in: CGRect(origin: .zero, size: self.size))

            return UIGraphicsGetImageFromCurrentImageContext()
        }
    }
}

UIGraphicsBeginImageContextWithOptions was deprecated, use UIGraphicsImageRenderer instead.

extension UIImage {
    func normalizedImage() -> UIImage {
        guard imageOrientation != .up else {
            return self
        }
        return UIGraphicsImageRenderer(size: size, format: .preferred())
            .image {
                draw(in: $0.format.bounds)
            }
    }
}

@ChrisXu thank you :)
What should i pass for this label?)

@Sam-Spencer thank you, it helped. I used your version eve though there was newer which was reported to have no memory leak, because it's the most recent which works as is. The last one requires me to pass something for the for labels.

In my case, your solution was not enough. I was having cropped image saved in some broken cropping.

Here how I used it:

func cropImage(_ image: UIImage, x: CGFloat, y: CGFloat, width: CGFloat, height: CGFloat) -> UIImage? {
    let rectToCrop = CGRect(x: x, y: y, width: width, height: height)
    let rect = CGRect(x: rectToCrop.origin.x, y: rectToCrop.origin.y, width: rectToCrop.width, height: rectToCrop.height)

    guard let cropped = image.fixedOrientation()?.cgImage?.cropping(to: rect) else {
        return nil
    }
    return UIImage(cgImage: cropped, scale: image.scale, orientation: .up)
}

And saving like

UIImageWriteToSavedPhotosAlbum(imageCropped, nil, nil, nil)

My problem was that i forgot to change image.imageOrientation to .up in the last line of the cropping function

UIImage(cgImage: cropped, scale: image.scale, orientation: .up)