Simple wait animation in ios 5 on view controller

I have a simple ViewController with 5 shortcuts, each of which is dynamically populated with data at runtime as a result of parsing regular expressions. I want to show any simple "Wait" animation while the tags receive their data to inform users that processing is in progress.

I read a lot of SO solutions that are more or less trying to do something like this, but I can’t get the simplest working code.

To begin with, I do not need how much% of the work is done, i.e. no progress bar. Just wait. Later I can add this logic. I need to start now!

This should have worked, but it’s not: (