I have a view controller in my app that has a navigation bar dragged on it in the storyboard. It was working fine in the iOS 6 but in iOS 7 it look like this:
I suggest you in your viewDidLoad method you try:
self.navigationController.navigationBar.translucent = NO;
(by default it is yes now)
https://developer.apple.com/library/ios/documentation/uikit/reference/UINavigationBar_Class/Reference/UINavigationBar.html#//apple_ref/occ/instp/UINavigationBar/translucent