Open Radar

 
Summary:
BUG:    When switching between multitasking to non-multitasking in an app that
         has UISplitViewControllers embedded in a UITabBarController in Portrait,
         the Master View of the UISplitViewControllers on other tabs get phantom
         ViewWillDisappear calls. This happens even if the views were never
         navigated to. This means you can get ViewWillDisappear calls without
         ever receiving ViewWillAppear calls for these views.
 
ADDITIONAL:
         1. This has been reproduced on iOS 10 and iOS 11 Beta
                      * Reproducing on iOS 10 is a bit trickier. You must go to the smallest multitasking size in landscape, and then sometimes it will occur in Portrait/Landscape sometimes when coming out of multitasking.
         2. It is only the Master View Controller that gets the premature
             ViewWillDisappear calls
         3. In Landscape the problem does not manifest
         4. If the SplitViewControllers use the preferredDisplayMode allVisible,
             the problem does not manifest
         5. If non-UISplitViewControllers are used as the other tabs, the problem
             does not manifest
         6. (2-5) lead me to believe it's a bug in how the Primary Popover

Steps to Reproduce:
SETUP:  The root view controller is a UITabBarController. It contains, as its
         children, 3 UISplitViewControllers. Each UISplitViewController contains
         a MasterViewController embedded in a UINavigationController and a
         DetailViewController embedded in a UINavigationController.
 
STR:    Steps to Reproduce -
         1. Open app on iPad in Portrait
         2. Go into Multitasking (open a side-by-side app)
         3. Shrink test app to the smallest allowable size
         4. Re-expand out of Multitasking while remaining in Portrait
         5. Note in the console loging showing "b" and "c" disappearing, but
             never appearing.

Expected Results:
ViewWillDisappear is not called when the view is not on screen and not disappearing.

Observed Results:
The Master View of the UISplitViewControllers on other tabs get phantom ViewWillDisappear calls. This happens even if the views were never navigated to. This means you can get ViewWillDisappear calls without ever receiving ViewWillAppear calls for these views.

Version:
Reproduced on iOS 10 and iOS 11 Beta 3