I am facing this issue with few apps, for example in this case with RedLaser. I am sure that this is not a problem with the app since the bar looks fine on other phones (i.e. text is written in black over a white background).
I have tried deleting the app and reinstalling it. I have also tried resetting the iPhone settings (iOS 7.0.3 on iPhone 5). But I am still facing this problem.
Is there some setting in the phones which forces the text to be white for some apps?