Open Radar

 
Sample code:
https://www.dropbox.com/s/xxx9pkagnd3gbri/DBAppDelegate.m.txt?dl=0

Summary:
The top view controller on the stack of a UINavigationController will not get invoked with the `willMoveToParentViewController:` or `didMoveToParentViewController:` methods when the navigation controller's `setViewControllers:animated:` method is called.

According to the docs for `willMoveToParentViewController:`:

"If you are implementing your own container view controller, it must call the willMoveToParentViewController: method of the child view controller before calling the removeFromParentViewController method, passing in a parent value of nil."

It seems to indicate that child view controllers will have their willMoveToParentViewController: method invoked when they are removed from their parent container view controller, but this strangely does not seem to be the case for UINavigationControllers.

Steps to Reproduce:
1. Create a UINavigationController (`nav`) with a few view controllers in the stack, e.g. `@[ vc1, vc2, vc3 ]`.
2. Call `[nav setViewControllers:@[ someOtherVc ] animated:YES]`.
3. Note that the `willMoveToParentViewController:` and `didMoveToParentViewController:` are only called on `vc1` and `vc2`, but not the top view controller `vc3`.


Expected Results:
All original view controllers to be called with the `*MoveToParentViewController:` methods.

Actual Results:
Only the non-top view controllers are called with the `willMoveToParentViewController:` and `didMoveToParentViewController:` methods.

Version:
iOS 7.1 (11D167)

Notes:
Also confirmed that this exists with the current beta of iOS 8 (Beta 5).



Configuration:
iPhone 5 and iPad Air