[特斯拉组件]iOS 高性能 PageController

1.组件介绍

Page是企鹅FM研发的分页组件，包括支持分页非交互切换（通过方法调用导航切换）和交互切换（屏幕的手势滑动），多个分页Controller和View的管理。

1.1需求背景

为什么弃用UIPageViewController,首先介绍一下UIPageViewController,这是系统为开发者定制的分页组件，提供了两种分页切换的效果，一是滑动 二是翻页。且提供了前后切换的回调。

a) UIPageViewController在iOS8以下的系统运行是有问题的，可以参考stackFlow上的症状描述https://stackoverflow.com/questions/12939280/uipageviewcontroller-navigates-to-wrong-page-with-scroll-transition-style/12939384#12939384

This is actually a bug in UIPageViewController. It occurs only with the scroll style (.Scroll) and only after calling setViewControllers:direction:animated:completion: with animated:YES. Thus there are two workarounds:

Don’t use UIPageViewControllerTransitionStyleScroll.

Or, if you call setViewControllers:direction:animated:completion:, use animated:NO.

To see the bug clearly, call setViewControllers:direction:animated:completion: and then, in the interface (as user), navigate left (back) to the preceding page manually. You will navigate back to the wrong page: not the preceding page at all, but the page you were on when setViewControllers:direction:animated:completion: was called.

The reason for the bug appears to be that, when using the scroll style, UIPageViewController does some sort of internal caching. Thus, after the call to setViewControllers:direction:animated:completion:, it fails to clear its internal cache. It thinks it knows what the preceding page is. Thus, when the user navigates leftward to the preceding pag