Crash on iOS 8 if trying to present a controller in 'showWithCompletion:'

[AbhaySingh]

Steps to reproduce:

1. Add code to present a UIViewController modally in 'showWithCompletion:'
2. Present alertView, dismiss controller and present alertView again.
3. Do step 2 a couple of times and it crashes.

Stack trace of the crash:

This runs fine on iOS7 though.