ImageScanner+UIImagePickerControllerDelegate.swift

extension ImageScanner: UIImagePickerControllerDelegate {

    func imagePickerController(_ picker: UIImagePickerController, didFinishPickingMediaWithInfo info: [UIImagePickerController.InfoKey : Any]) {
        guard let uiImage = info[UIImagePickerController.InfoKey.originalImage] as? UIImage else {
            dismissController(picker, with: .failure(ImageProviderError.internalError))
            return
        }

        DispatchQueue.background.async {
            let result = self.postProcessImage(uiImage)
            self.dismissController(picker, with: result)
        }
    }
}