I have got this super weird bug in my current project. To understand what is going on, I narrowed down everything to the simplest app, which can be downloaded here:
download simple example here (no autoreleasing of the mentioned indexes array here)
It seems like the method: sectionIndexTitlesForTableView has something to do with it as the bug does not appear when it is not implemented. Super weird thing though: When it gets stuck and you shake the device it responds again. If you downloaded the code above, in the app you have to press the button, scroll down go back while its still scrolling and press it again and it will definitely crash after a few times. If not just restart it and try it again. It will crash eventually.
Turned out that this is an iOS bug. I have not filed it yet. But I will update this post as soon as I have.