嵌入containerView中的PageViewController显示先前视图的小边距

我创建了一个带有containerView的viewController,其中嵌入了pageViewController。在这个页面控制器中,我在里面添加了3个视图控制器。这看起来很好,但是每次我滑动到下一个视图时,它似乎会在前一个视图的一侧显示一点空白。这是什么原因造成的?

查看DidLoad

    if let firstViewController = orderedViewControllers.first {
        self.pageViewController?.setViewControllers([firstViewController],
            direction: .Forward,
            animated: true,
            completion: nil)
    }

新视图控制器

func newViewController(view: String) -> UIViewController {
    return UIStoryboard(name: "Main", bundle: nil).instantiateViewControllerWithIdentifier(view)
}

页面控制器委托

extension CameraViewController: UIPageViewControllerDataSource {
    func pageViewController(pageViewController: UIPageViewController,
        viewControllerBeforeViewController viewController: UIViewController) -> UIViewController? {
            guard let viewControllerIndex = orderedViewControllers.indexOf(viewController) else {
                return nil
            }

            let previousIndex = viewControllerIndex - 1

            // User is on the first view controller and swiped left to loop to
            // the last view controller.
            guard previousIndex >= 0 else {
                return orderedViewControllers.last
            }

            guard orderedViewControllers.count > previousIndex else {
                return nil
            }

            return orderedViewControllers[previousIndex]
    }

    func pageViewController(pageViewController: UIPageViewController,
        viewControllerAfterViewController viewController: UIViewController) -> UIViewController? {
            guard let viewControllerIndex = orderedViewControllers.indexOf(viewController) else {
                return nil
            }

            let nextIndex = viewControllerIndex + 1
            let orderedViewControllersCount = orderedViewControllers.count

            // User is on the last view controller and swiped right to loop to
            // the first view controller.
            guard orderedViewControllersCount != nextIndex else {
                return orderedViewControllers.first
            }

            guard orderedViewControllersCount > nextIndex else {
                return nil
            }

            return orderedViewControllers[nextIndex]
    }
}