ios 三种页面切换，翻书，碎片等效果。。。采用opengl实现，不会被苹果reject-ios three kinds of switching pages, open book, debris and other effects. . . Use opengl achieve, not Apple reject

XBPageCurl 实现了类似翻书动画效果的视图切换方式，很像 Google 地图。-XBPageCurl achieve a similar view of open book animation switching mode, much like Google Maps.