I am working on an application to learn iOS programming, it’s a simple calculator app.
The nib file shows all of the button displaying correctly:
Whereas when the app is run in the simulator the buttons on the last row are not displayed correctly.

All buttons have the state config as default, and a plain font set to 15 points system bold.
I have tried lots of settings for the properties of the UI buttons to no effect, and it seems to only effect the bottom row.
Any ideas ?
What I’ve found is that if I disable Autolayout, it fixes the problem. However, the buttons lose their positioning on the screen. But when I re-enable Autolayout it re-arranges the button as intended and the text on the UIButton is also restored. Again, I am also not sure how this works but it is a workaround for iOS 6.0. I have not tried adding new buttons and observing whether this fix is persistent.