Open Radar

 
Summary:
I have a UITabBarController with more than 8 viewControllers. Most of the viewControllers are UINavigationControllers with their own viewController stacks. When in portrait-orientation the iPhone 6 Plus displays 4 tabBarItems and a "More" button. In landscape-orientation the iPhone 6 Plus displays 7 tabBarItems and a "More" button. The problem occurs if the user is on the 6th or 7th tab in landscape-orientation, rotates to portrait-orientation and then back to landscape-orientation. At this point the user is presented with an empty UINavigationController with a black background. In portrait-orientation it will still be fine, but it will never recover in landscape-orientation. The console also starts displaying the "Unbalanced calls to begin/end appearance transitions" message when rotating back to portrait-orientation.

I suspect that during the first access of the sixth or seventh tab in landscape-orientation the viewController hierarchy is left intact as intended. Once it is rotated to portrait-orientation the contents of the tab's UINavigationController are removed and pushed onto the moreNavigationControllers stack. Once the phone is rotated back to landscape-orientation the viewControllers are never properly inserted back into their original navigationController and instead remain inside of moreNavigationController.

Steps to Reproduce:
1. Create a new 'Tabbed Application' project in XCode. (I've uploaded a sample project)
2. Copy the provided viewControllers and attach the copies to the UITabBarController under the "viewControllers" relation until you have at least 9 viewControllers.
3. Make sure that at least the sixth and seventh viewControllers are embedded inside of a UINavigationController.
4. Run the project on the iPhone 6 Plus simulator.
5. Rotate to landscape mode.
6. Select the sixth tab.
7. Rotate to portrait.
8. Rotate back to landscape.
9. Notice the black background. If you put in a breakpoint and 'po' the contents of moreNavigationController you will notice that the view controller associated with the  sixth tab's UINavigationController is still attached.

Expected Results:
I would expect the original contents of the sixth and seventh tab to be displayed in their original parent UINavigationController when rotating back to landscape-orientation from portrait-orientation.

Actual Results:
The sixth and seventh tabs would look like empty UINavigationControllers with black backgrounds when in landscape-orientation after a couple of rotations.

Version:
8.3 (12F70)

Notes:
It may also be worth noting that if the user is looking at the first item in the "More" tab (eighth view controller) in landscape-orientation and then rotates to portrait-orientation they are redirected to the fifth view controller.

Configuration:
Only occurs on iPhone 6 Plus in Landscape-Orientation