ios - Trigger an event / method when UIWindow RootViewController changes SWIFT

Question

I'm working on an iOS framework. I have a requirement to log events when user enters or exits a particular View Controller. For that I was thinking if somehow I could be able to register a notification to trigger a custom method when the root view controller changes. Or perhaps use KVO. But I don't understand how to do this from an implementation point of view since I cannot find any such notification.

Any help in this regard would be highly appreciated. Thanks.

Please note that this is a framework project. So the framework is built and then added/embedded into another app. I don't have any information about the view controllers in that app. The only thing I can access is UIWindow's root view controller. So, I need to know when a change occurs in it.

Answer 1

得到它的工作。答案是方法混搭。不推荐作为该问题的第一个解决方案。但是，如果仔细使用并且您确切地知道自己在做什么，那就是要走的路。

在这里找到了一篇非常有用的文章：Method Swizzling

Answer 2

您可以覆盖UIViewController'sviewWillAppear并viewWillDisappear知道何时将呈现/关闭视图控制器。

或者，您可以使用viewDidAppear和viewDidDisappear。

如果您想代表用户进行日志记录，那么您实际上有两个选择：

1.提供一个基础UIViewController子类供他们覆盖，在viewWillAppear/ viewWillDisappearmethods中实现所需的逻辑。

2.实现方便的方法（如logAppearEvent，logDisappearEvent），以便他们在子类中自己手动调用UIViewController。