Open Radar

 
Summary:
The UINavigationController does not implement childViewControllerForStatusBarStyle to return the topmost view controller in its stack. 

When using "View controller-based status bar appearance" with a UINavigationController none of the UINavigationController's viewControllers will get the -preferredStatusBarStyle method called. 

This renders the view controller based status bar appearance pretty useless when using a UINavigationController, and can be fixed by subclassing UINavigationController or creating a custom container view controller but this is an annoyance and does not seem like it should be necessary just to get the preference to be observed.

Steps to Reproduce:
1. Create a new iOS project with the empty template in Xcode
2. Set UIViewControllerBasedStatusBarAppearance to YES in the applications' info.plist
3. Create a UIViewController subclass with an implementation for -preferredStatusBarStyle
4. In the app delegate create a UINavigationController with the UIViewController subclass as its rootViewController
5. Set the window's rootViewController to that UINavigationController

Expected Results:
preferredStatusBarStyle would be called on the UIViewController subclass and the status bar style would be updated to whatever the style returned in that method

Actual Results:
preferredStatusBarStyle is never called on the UIViewController that is set as the rootViewController of the UINavigationController. Calling setNeedsStatusBarAppearanceUpdate also has no effect.

Version:
7.0.2

Notes:
Creating a subclass of the UINavigationController and returning self.topViewController in childViewControllerForStatusBarStyle and childViewControllerForStatusBarHidden fixes this problem.

Sample Code: https://github.com/danielrhammond/Preferred-Status-Bar-Style-Navigation-Controller-Experiment

Workaround: https://gist.github.com/danielrhammond/6894539