RxActionSheet.swift

private var selectedOption: Observable<ImageSource> {
        return Observable.create { [weak self] observer in
            guard let `self` = self else {
                observer.onCompleted()
                return Disposables.create()
            }
            let actionSheet = self.prepareActionSheet(with: observer)
            self.presenter?.present(actionSheet)

            return Disposables.create {
                actionSheet.dismiss(animated: true, completion: nil)
            }
        }
    }

    private func prepareActionSheet(with actionTapObserver: AnyObserver<ImageSource>) -> UIAlertController {
        let actionSheet = UIAlertController(title: nil, message: nil, preferredStyle: .actionSheet)
        prepareActionSheetActions(with: actionTapObserver)
                .forEach { actionSheet.addAction($0) }
        return actionSheet
    }

    private func prepareActionSheetActions(with tapObserver: AnyObserver<ImageSource>) -> [UIAlertAction] {
        var actions = createSourcesActions(with: tapObserver)
        let cancel = createCancelAction(with: tapObserver)
        actions.append(cancel)
        return actions
    }

    private func createSourcesActions(with tapObserver: AnyObserver<ImageSource>) -> [UIAlertAction] {
        return sources.map { source in
            return UIAlertAction(title: source.description, style: .default) { _ in
                tapObserver.onNext(source)
                tapObserver.onCompleted()
            }
        }
    }

    private func createCancelAction(with tapObserver: AnyObserver<ImageSource>) -> UIAlertAction {
        return UIAlertAction(title: Strings.cancel, style: .cancel) { _ in
            tapObserver.onCompleted()
        }
    }