Question related to Bronze challenge


I understood how using:

self.window.rootViewController.view.backgroundColor = [UIColor xxxxxx];

was used to change the window color based upon a proximity notification but what if we wanted to change the background color for the actual photo. So in the XIB file we selected background color to be light grey via the drop box in Xcode. What if we wanted to use the proximity notification to change that value in the XIB file?