Open Radar

 
Summary:
When a UINavigationController is the seventh item in a UITabBarController with 9 or more tabs, then the app window is resized to smaller size with Split View, then returned to the original size, the UINavigationController shows a black rectangle instead of showing its Root View Controller.

Steps to Reproduce:
1- Open Xcode and create a new iOS "Tabbed Application"
2- Open Main.storyboard
3- Add a UINavigationController to the storyboard
4- ctrl-drag from the UITabBarController to the new UINavigationController and select Relationship Segue -> view controllers
5- Do steps 3 and 4 for seven times until you have a total of 9 items in the UITabBarController tab bar (2 views added automatically, and 7 added manually)
6- Name the items First, Second, Third, ..., Ninth (for easier demonstration of the bug)
7- Run the app on an iPad that supports Split View multitasking such as iPad Mini 4
8- Tap "Seventh" item on the tab bar to select it
9- Run another app in Split View mode (not Slide Over mode)
10- If the iPad is in landscape, drag the Split View vertical divider to the middle of the screen to make the demo app smaller
11- Drag the Split View vertical divider back to the right side of the screen to close Split View mode
12- You'll notice the screen shows a black rectangle instead of the "Seventh" Root View Controller.

Expected Results:
The UINavigationController should show the same contents as it was before the app was resized

Actual Results:
The UINavigationController shows a black rectangle instead

Version:
iOS 9.3.1 (13E238), Xcode 7.3 (7D175)

Notes:
My analysis of the bug:

1- When the app window becomes smaller, the Seventh UINavigationController gets removed from the UITabBarController  and gets attached to the "More" ViewController
2- When the app window becomes big again, the Seventh UINavigationController gets removed from the "More" ViewController and is returned to be a direct child of UITabBarController
3- However, the Root View Controller of the Seventh UINavigationController remains attached to the "More" ViewController and doesn't return to the UITabBarController along with its parent UINavigationController 

Configuration:
iPad Mini 4

Attachments:
'demo.zip' and 'IMG_0006.jpg' were successfully uploaded.