ImageScanner.swift

final class ImageScanner: NSObject {
    private var completion: Completion?

    func image(with completion: @escaping Completion) {
        guard self.completion == nil, UIImagePickerController.isSourceTypeAvailable(.camera) else {
            completion(.failure(ImageProviderError.startFailure))
            return
        }
        self.completion = completion

        let pickerController = UIImagePickerController()
        pickerController.delegate = self
        pickerController.sourceType = .camera
        UIViewController.topmostViewContoller.present(pickerController, animated: true)
    }
}