load加载分析
load加载分析 如果是有两个分类，分别是UIViewController+A和UIViewController+B，他们分别实现自己的load方法，最后load方法方法调用的顺序取决于什么？
UIViewController+A and UIViewController+B are two categories that implement their own load methods. The order in which the load methods are called depends on the loading order of the classes in the Compile Sources section of Build Phases. If two categories have the same method name, the method of the last loaded file will be called. If the method names are different, they will not affect each other.
