实现有特殊动画的视图弹出和消失效果，这种弹出视图效果在Letterpress app中使用过。具体效果看动画吧。 适用环境：Xcode 4.5, iOS 5.0 以上。-A view to achieve a special animation effects pop up and disappear, this pop-up view of the effect of the use in Letterpress app too. Specific effects see the