Try it ...
self.navigationController.navigationBar.backgroundColor=[UIColor colorWithRed:215.0f/255.0f green:215.0f/255.0f blue:215.0f/255.0f alpha:1.0f];
For iOS > 7
self.navigationBar.barTintColor=[UIColor colorWithRed:215.0f/255.0f green:215.0f/255.0f blue:215.0f/255.0f alpha:1.0f];
self.navigationBar.tintColor = [UIColor whiteColor];
self.navigationBar.translucent = NO;