How to flip UIImage horizontally with Swift?

Question

The solution to do UIImage flipping is with the Objective-C code:

[UIImage imageWithCGImage:img.CGImage scale:1.0 orientation: UIImageOrientationDownMirrored         


        

Answer 1

There is couple of similar questions on SO. And I believe it's worth to post solution using CoreImage here too.

Please note: when getting final UIImage, it's necessary to convert to CGImage first to respect extent of CIImage

extension UIImage {
    func imageRotated(by degrees: CGFloat) -> UIImage {

        let orientation = CGImagePropertyOrientation(imageOrientation)
        // Create CIImage respecting image's orientation 
        guard let inputImage = CIImage(image: self)?.oriented(orientation) 
            else { return self }

        // Flip the image itself
        let flip = CGAffineTransform(scaleX: 1, y: -1)
        let outputImage = inputImage.transformed(by: flip)

        // Create CGImage first
        guard let cgImage = CIContext().createCGImage(outputImage, from: outputImage.extent) 
            else { return self }

        // Create output UIImage from CGImage
        return UIImage(cgImage: cgImage)
    }
}