You have a bug on line 173.
Which is a sarcastic way of saying: "How are we supposed to know what you're doing wrong when you provided almost no information about your project?"
Are you using XIBs or storyboards? What version of Xcode? How is your view controller's view hierarchy structured? What are you doing to create a background? If you're doing it all in IB, show a screenshot of the outline view of your XIB/Storyboard scene. If you're using code, post that code.
Also show a screen-shot of the simulator that shows the problem you are having.