UIViewController或UINavigationController设置它的视图的大小吗?

I have several UIViewControllers, loaded via a UINavigationController, where I override loadView, and setup a custom view to display. I am having problems with setting the frames of some of the subviews, and maybe the view itself. I think that either the UINavigationController or the UIViewController is able to force it's view to fill the screen when displayed.I have several UIViewControllers, loaded via a