以编程方式更改UIPageViewController页面

Question

我正在使用UIPageViewController，其Next按钮具有相同的功能，例如轻扫到下一个视图。

@IBAction func next(sender: UIButton!) {

    let pageContentViewController = pageViewController.viewControllers![0] as! WelcomeViewController
    let index = pageContentViewController.pageIndex + 1

    if index < titleArray.count {
        let vctoMove = self.viewControllerAtIndex(index) as WelcomeViewController
        let viewControllers = NSArray(objects: vctoMove)
        pageViewController.setViewControllers(viewControllers as? [UIViewController], direction: .Forward, animated: true, completion: nil)
    }
}