How to set title of Navigation Bar from a View Controller of a subview?

Question

I've a view controller having navigation bar in starting.
After some UIViewConrollers I have added a tabbar controller where I've created four tab bars and four view controllers for each tab bar.
Now if I create tabbars with navigation bars related to each tab it shows two navigation bars at top, if create tabbars without navigation bar it will show only one tabbar but I am not able add title, corresponding to each tab view controller, to that navigation bar
Here is the code in which I created the tab bar

EventDetailViewController *firstViewController = [[EventDetailViewController alloc]init];
firstViewController.tabBarItem = [[[UITabBarItem alloc]initWithTitle:@"Home" image:[UIImage imageNamed:@"Multimedia-Icon-Off.png"] tag:2]autorelease];                                 MoreInfo *secondViewController = [[MoreInfo alloc]init];
secondViewController.tabBarItem = [[[UITabBarItem alloc]initWithTitle:@"Info" image:[UIImage imageNamed:@"Review-Icon-Off.png"] tag:0]autorelease];

PlaceInfoViewController *thirdViewController = [[PlaceInfoViewController alloc]init];
thirdViewController.tabBarItem = [[[UITabBarItem alloc]initWithTitle:@"Lugar" image:[UIImage imageNamed:@"Place-icon-OFF.png"] tag:1]autorelease];

FavoritesViewController *forthViewController = [[FavoritesViewController alloc]init];
forthViewController.tabBarItem = [[[UITabBarItem alloc]initWithTitle:@"Compartir" image:[UIImage imageNamed:@"Compartir-Icon-Off.png"] tag:3]autorelease];

UITabBarController *tabBarController = [[UITabBarController alloc] initWithNibName:nil bundle:nil];
tabBarController.viewControllers = [[NSArray alloc] initWithObjects:firstViewController, secondViewController, thirdViewController, forthViewController, nil];
tabBarController.view.frame = self.view.frame;
[self.view addSubview:tabBarController.view];

[firstViewController release];
[secondViewController release];
[thirdViewController release];
[forthViewController release];

Answer 1

I got the solution myself by passing the reference of the navigation Item of the parent to the child view controller..thanx everyone for helping... :)