I am trying to add a custom control as the titleView in a UINavigationBar. When I do so, despite setting the frame and the properties that would normally assume full width,
Setting the titleView of your view's navigationItem will never do the trick. Instead, you can add a subView to the navigation controller's navigationBar :
UIView* ctrl = [[UIView alloc] initWithFrame:navController.navigationBar.bounds];
ctrl.backgroundColor = [UIColor yellowColor];
ctrl.autoresizingMask = UIViewAutoresizingFlexibleWidth;
[navController.navigationBar addSubview:ctrl];