Instead of adding viewController5 to the tab bar controller's view controllers,, add the navigation controller.
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
// Override point for customization after application launch.
UIViewController *viewController1 = [[FirstViewController alloc] initWithNibName:@"FirstViewController" bundle:nil];
UIViewController *viewController2 = [[SecondViewController alloc] initWithNibName:@"SecondViewController" bundle:nil];
UIViewController *viewController3 = [[ThirdViewController alloc] initWithNibName:@"ThirdViewController" bundle:nil];
UIViewController *viewController4 = [[FourthViewController alloc] initWithNibName:@"FourthViewController" bundle:nil];
UIViewController *viewController5 = [[FifthViewController alloc] initWithNibName:@"FifthViewController" bundle:nil];
self.tabBarController = [[UITabBarController alloc] init];
self.navigationController = [[UINavigationController alloc] initWithRootViewController:viewController5];
self.tabBarController.viewControllers = @[viewController1, viewController2,viewController3,viewController4,self.navigationController];
self.window.rootViewController = self.tabBarController;
[self.window makeKeyAndVisible];
return YES;
}