Actually, this might not be correct, since plain ol' `UINavigationController` itself does not implement the delegate protocol. Any other subclass of `UINavigationController` that does implement the protocol will also have the method implemented here unless it overrides it, in which case the subclass's implementation will take precedence. So there are some cases in which this still won't work that might be use to document:

- Subclasses of `UINavigationController` that provide their own `didShowViewController:` method.
   - The method in the subclass will always override the one provided by this category
- Other categories on `UINavigationController` that implement the delegate protocol and provide `didShowViewController:`
   - The order of category method loading is indeterminate, so the other category's implementation might take over this one.