ipad Tab bar application with navigation controller

I am working on an iPad application (with orientation support). I have choose tab bar application for that. I am not finding out how开发者_JS百科 to implement navigation controller in to it for pushing other view controller. I have to change 1st tab controllers view with another viewcontrollers view I have used following code for changing my view

UINavigationController*  theNavController = [[UINavigationController alloc] initWithRootViewController:rootVC];

[theNavController pushViewController:nextVC animated:NO];

// Display the nav controller modally.          
[self presentModalViewController:theNavController animated:YES];

My problem is that while doing this my tab bar gets hidden. How can I prevent my tab bar or how can i use navigation bar with tab bar.

Please help me.