How to show UIToolBar at bottom of UIView after pop to root of UINavigationController?

Question

I can't show a UIToolbar that was at the bottom of a view, where the view pushed a navigation controller and then popped back to the view using the back button.

In a NIB I've created:

UIViewController RootViewController containing a
   UIView  containing a
       UIToolbar at bottom of UIView

In RootViewController I create next UIViewController, NextViewController, within which I create a NavigationController:

UIViewController RootViewController containing a
   UIViewController NextViewController containing a 
      NavigationController

In NextViewController I can see the UIToolbar from RootViewController. When I pop back to NextViewController, using the back button, from the NavigationController I can no longer see the UIToolbar from RootViewController. Does anyone know how to make the UIToolbar visible?

One approach I thought would work was to get a pointer to the UIToolbar and add it as a subview to the navigation controller as:

AppDelegate *appDelegate    = [[UIApplication sharedApplication] delegate];
RootViewController *rootViewController = appDelegate.rootViewController;

UIView *rootViewUIView               = rootViewController.view;
UIToolbar *rootViewUIToolbar         = rootViewUIView.toolbar;

[self.navigationController.view addSubview:rootViewUIToolbar];

But I get the error: "Request for member rootViewUIToolbar in something not a structure or a union" for the line:

UIToolbar *rootViewUIToolbar         = rootViewUIView.toolbar;

Any ideas on how to show the toolbar after popping back to the root view from the navigation controller using the back button?