iOS 7 Only App Crashes at Startup

Question

I recently changed my xcode project to be iOS 7 only instead of supporting iOS 5. After making this change as soon as the app starts I get this message in the console.

Answer 1

This problem arises due to giving different NSAttributedString.key and value to attributed String.

Error: let prefixAttribute = [ NSForegroundColorAttributeName: UIFont(name: "HelveticaNeue-Light", size: 11.0), NSFontAttributeName: UIColor.darkGray]

Solved: let prefixAttribute = [ NSFontAttributeName: UIFont(name: "HelveticaNeue-Light", size: 11.0), NSForegroundColorAttributeName: UIColor.darkGray]

I have interchanged colorarrtibute with font and vice versa