class ViewControllerOne: UIViewController, Pageable {

    // MARK: - Paging implicit properties

    var pageTitle: String {
        return "vcOne"
    }

    func pagingViewDidShow() {
        textfield.becomeFirstResponder()
    }
}

    /// This function is used to only at the pagingView (top bar),
    /// with an amount of titles given to it.
    func exampleAddingOnlyThePagingView() {
        // PagingView titles
        let pagingView = PagingView(titles: ["Red", "Gray", "Blue"])

        // PagingView Delegate
        pagingView.delegate = self

        // Add pagingView
        pagingView.translatesAutoresizingMaskIntoConstraints = false
        view.addSubview(pagingView)

        // give the pagingView some contstraints
        pagingView.topAnchor.constraint(equalTo: view.topAnchor, constant: 16).isActive = true
        pagingView.leadingAnchor.constraint(equalTo: view.leadingAnchor).isActive = true
        pagingView.trailingAnchor.constraint(equalTo: view.trailingAnchor).isActive = true
        pagingView.heightAnchor.constraint(equalToConstant: 100).isActive = true
    }

    /// Here we instantiate some viewControllers, and show the pagingViewController with the initialized viewControllers.
    /// We can add this PagingViewController to a containerView so we have a baseController that is in control of the pagingViewController.
    func exampleAddingThePagingViewController() {
        let controller1 = ViewControllerOne()
        let controller2 = ViewControllerTwo()
        let controller3 = ViewControllerThree()

        let controller = PagingViewController(viewControllers: [controller1, controller2, controller3], initialIndex: 0)
        self.present(controller, animated: true, completion: nil)
    }