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)
    }
}

Its saved my time! Thanks all !!!

Amazing. Great work buds.

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)
            }
    }
}