UIPageViewControllerDelegate

    /// 手勢開始時觸發(fā)
    /// - Parameters:
    ///   - pageViewController:
    ///   - pendingViewControllers: 
    func pageViewController(_ pageViewController: UIPageViewController, willTransitionTo pendingViewControllers: [UIViewController]) {
        <#code#>
    }

//當手勢啟動的轉換結束時發(fā)送。
//“finished”參數(shù)指示動畫是否完成，
//而“completed”參數(shù)指示轉換是完成還是退出（如果用戶提前放手）。

@available(iOS 5.0, *)
    optional func pageViewController(_ pageViewController: UIPageViewController, didFinishAnimating finished: Bool, previousViewControllers: [UIViewController], transitionCompleted completed: Bool)

/// 手勢動作發(fā)起的動畫結束時觸發(fā)
    /// - Parameters:
    ///   - pageViewController:
    ///   - finished: 動畫是否完成
    ///   - previousViewControllers: 
    ///   - completed: 翻頁動作是否完成【用戶是否取消了動作】
    func pageViewController(_ pageViewController: UIPageViewController, didFinishAnimating finished: Bool, previousViewControllers: [UIViewController], transitionCompleted completed: Bool) {
        
    }

/// 設置書脊的位置，當時翻頁類型時在init方法中設置書脊位置會引起閃退
    /// - Parameters:
    ///   - pageViewController: 
    ///   - orientation: none、min、mid、max
    func pageViewController(_ pageViewController: UIPageViewController, spineLocationFor orientation: UIInterfaceOrientation) -> UIPageViewController.SpineLocation {
        return .min
    }

UIPageViewControllerDataSource

/// 前一頁
    /// - Parameters:
    ///   - pageViewController: <#pageViewController description#>
    ///   - viewController: <#viewController description#>
    func pageViewController(_ pageViewController: UIPageViewController, viewControllerBefore viewController: UIViewController) -> UIViewController?

/// 后一頁
    /// - Parameters:
    ///   - pageViewController: <#pageViewController description#>
    ///   - viewController: <#viewController description#>
    func pageViewController(_ pageViewController: UIPageViewController, viewControllerAfter viewController: UIViewController) -> UIViewController?