How to Notify RootViewController of View Changes

I have added a UIButton to a toolbar that is only accessible via the RootViewController (which has a navigation bar and toolbar) of my app. When navigating to another view, I hide the开发者_开发知识库 UIButton, but when I go back to the initial screen (a map view) the UIButton remains hidden and I must unhide it. Since it is the RootViewController I am doing this in, viewWillAppear is not called, so I cannot use that method.

I am wondering if there is any way the RootViewController knows when a view is being popped off the navigationController stack, if so, how would you suggest I check for this? Is there any way you would recommend implementing this?

Thanks in advance!

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if your app using UINavigationController for navigation then viewWillAppear will obviously called