The purpose of the LGSemiModalNavController is to allow you to show a view controller a dynamically set height over another view controller.

The effect this custom transition gives off is that a view partially springs up from the bottom of the screen and into place. The view that gets sprung over, gets scaled down by a customizable amount.

lgsemimodalnavcontroller的目的是允许你显示一个视图控制器动态设置高度在另一个视图控制器。
这个自定义转换的效果是，一个视图部分从屏幕底部弹出并进入。被激活的视图会被可定制的数量缩小。