为什么pushViewController在UIPageViewController中不起作用？

Question

我使用uipageViewController来滑动页面。每个页面都有自己的ViewController：ContentViewController。在其中一个页面我有按钮。当用户点击这个按钮时，它应该转到另一个ViewController（比如说主页）。当我单击按钮时它会改变状态，但重定向不起作用。似乎smth错误的pushViewController？

这是我的代码::

class ViewController: UIViewController, UIPageViewControllerDataSource {

    var pageViewController : UIPageViewController!
    var pageTitles : NSArray!
    var pageImages : NSArray!
    let controllers = ["FirstViewController","SecondViewController"]

@IBOutlet weak var restartButton: UIButton!

override func viewDidLoad() {
    super.viewDidLoad()
    self.pageTitles = NSArray(objects: "Explore", "Today Widget")
    self.pageImages = NSArray(objects: "page1","page2")



    self.pageViewController = self.storyboard?.instantiateViewControllerWithIdentifier("PageViewController")as! UIPageViewController

    self.pageViewController.dataSource = self
    var startVC = self.viewControllerAtIndex(0)as ContentViewController
    var viewControllers = NSArray(object: startVC)

    self.pageViewController.setViewControllers(viewControllers as! [UIViewController], direction: .Forward, animated: true, completion: nil)

    self.pageViewController.view.frame = CGRectMake(0,40,self.view.frame.width,self.view.frame.height - 60)


    self.addChildViewController(self.pageViewController)
    self.view.addSubview(self.pageViewController.view)
    self.pageViewController.didMoveToParentViewController(self)
    self.view.backgroundColor = UIColor(red: (25/255.0), green: (127/255.0), blue: (216/255.0), alpha: 1.0)
    // Do any additional setup after loading the view, typically from a nib.


}

override func didReceiveMemoryWarning() {
    super.didReceiveMemoryWarning()
    // Dispose of any resources that can be recreated.
}

@IBAction func restartAction(sender: AnyObject) {
    var startVC = self.viewControllerAtIndex(0)as ContentViewController
    var viewControllers = NSArray (object: startVC)

    self.pageViewController.setViewControllers(viewControllers as! [UIViewController], direction: .Forward, animated: true, completion: nil)
}

func viewControllerAtIndex(index : Int)->ContentViewController
{
    if (self.pageTitles.count == 0) || (index >= self.pageTitles.count){
        return ContentViewController();
    }
    var vc:ContentViewController = self.storyboard?.instantiateViewControllerWithIdentifier("ContentViewController")as! ContentViewController

    vc = self.storyboard?.instantiateViewControllerWithIdentifier(controllers[index])as! ContentViewController
    vc.pageIndex = index

    return vc;

}


func pageViewController(pageViewController: UIPageViewController, viewControllerBeforeViewController viewController: UIViewController) -> UIViewController? {

    var vc = viewController as! ContentViewController
    var index = vc.pageIndex as Int
    if (index == 0 || index == NSNotFound){
        return nil
    }
    index--
    return self.viewControllerAtIndex(index);
}

func pageViewController(pageViewController: UIPageViewController, viewControllerAfterViewController viewController: UIViewController) -> UIViewController? {
    var vc = viewController as! ContentViewController
    var index = vc.pageIndex as Int
    if (index == NSNotFound){
        return nil
    }
    index++
    if (index == self.pageTitles.count){
        return nil
    }

    return self.viewControllerAtIndex(index)
}

func presentationCountForPageViewController(pageViewController: UIPageViewController) -> Int {
    return self.pageTitles.count
}

func presentationIndexForPageViewController(pageViewController: UIPageViewController) -> Int {
    return 0
}
}


@IBAction func secondViewController(sender: AnyObject) {
    let next = self.storyboard?.instantiateViewControllerWithIdentifier("ThirdViewController") as?  ThirdViewController

    navigationController?.pushViewController(next!,animated: true)
}