nested pop animation can result in corrupted navigation bar
Finishing up a navigation transition in an unexpected state. Navigation Bar subview tree might get corrupted.
我出现这个错误的情况，输入框输入状态下push到下个页面返回的时候会出错，4上测试
nested pop animation can result in corrupted navigation bar
原文：http://www.cnblogs.com/hxwj/p/4778303.html