在push控制器时控制台出现下面打印：
Unbalanced calls to begin/end appearance transitions for <ICHomeVC: 0x16e79340>.
Unbalanced calls to begin/end appearance transitions for <TestVC: 0x16d8d7f0>.
原因是没有在viewWillAppear实现父类的
在push控制器时控制台出现下面打印：
Unbalanced calls to begin/end appearance transitions for <ICHomeVC: 0x16e79340>.
Unbalanced calls to begin/end appearance transitions for <TestVC: 0x16d8d7f0>.
原因是没有在viewWillAppear实现父类的
![吃透MVC，驯服烂代码 吃透MVC，驯服烂代码[图]](data:image/gif;base64,R0lGODlhAQABAIAAAP///wAAACwAAAAAAQABAAACAkQBADs=)