I think I have found a bug in the iOS 7 Simulat
It appears this is not a Simulator bug, but an iOS 7 bug as I have been able to reproduce it on a device now. I have created a new question for it here: iOS 7 BUG - NSAttributedString does not appear
The bug appears to be the combination of using NSUnderlineStyleAttributeName & NSParagraphStyleAttributeName as attributes for a NSAttributedString.
Following line causing the issue.
NSParagraphStyleAttributeName:paragraph
This Worked for me
//Swift
let underlineAttribute = [NSUnderlineStyleAttributeName:NSNumber(int: 1)];
lblMessage.attributedText = NSAttributedString(string: "Your text", attributes: underlineAttribute)
//Am33t