When I tap on the back button just before a deleted question loads (here's one for you to test with), the "Question not found" UIAlertController appears on the previous page and then the content goes black:

enter image description here

The content is restored if I tap on a UITabBarItem (the tab bar is still visible if I go back to a screen where there is one), but the keyboard will not show until I relaunch the app:

enter image description here

  • App Version:
  • Device: iPhone 4S
  • OS Version: Version 9.3.2 (Build 13F69)

This is quite easy to reproduce when you have a good internet connection -- just tap the link and press back immediately -- but with a slow internet connection you have to wait just a bit (but not too long) before pressing back.

Alright, I figured out why it stopped happening for me, and got it to happen again:

The bug doesn't occur if you press back so soon that "Question not found" doesn't appear at all.

It also doesn't happen if the popup appears during the back animation -- the animation has to stop before the it appears to trigger the bug.

It stopped happening for me because my Internet was fast enough that this short window of time between the popup not appearing and the animation not finishing didn't exist at all.

After more testing, I find it easiest to reproduce the bug by enabling Network Link Conditioner (in Settings->Developer) with the 3G preset, so the question doesn't load too fast.


1 Answer 1


This will be fixed in

The alert was presenting from the question view controller because its view was still in the view hierarchy even though it wasn't in the view controller hierarchy. It even produced this friendly warning in the console:

Presenting view controllers on detached view controllers is discouraged <...>.

Now I do a sanity check that the window and the parent view controller exist before presenting.

  • Yep, this appears to be fixed now! Thanks!
    – NobodyNada
    Jun 28, 2016 at 3:27

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