我应该为每个选项卡栏使用单独的 UINavigationController

根据Apple https://developer.apple.com/library/ios/#documentation/WindowsViews/Conceptual/ViewControllerCatalog/Chapters/CombiningViewControllers.html，我可以结合UINavigationController and UITabBarController使用代码，例如

MyViewController1* vc1 = [[MyViewController1 alloc] init];
MyViewController2* vc2 = [[MyViewController2 alloc] init];
MyViewController3* vc3 = [[MyViewController3 alloc] init];

MyNavRootViewController* vc4 = [[MyNavRootViewController alloc] init];
UINavigationController* navController = [[UINavigationController alloc]
                        initWithRootViewController:vc4];

NSArray* controllers = [NSArray arrayWithObjects:vc1, vc2, vc3, navController, nil];
tabBarController.viewControllers = controllers;

在此设置中，仅vc4有UINavigationController，但是如果我想要怎么办vc1-vc3还有UINavigationController？，我应该这样做吗..

MyViewController1* vc1 = [[MyViewController1 alloc] init];
UINavigationController* nv1 = [[UINavigationController alloc]
                        initWithRootViewController:vc1];

MyViewController1* vc2 = [[MyViewController2 alloc] init];
UINavigationController* nv2= [[UINavigationController alloc]
                        initWithRootViewController:vc2];

MyViewController1* vc3 = [[MyViewController3 alloc] init];
UINavigationController* nv3 = [[UINavigationController alloc]
                        initWithRootViewController:vc3];


NSArray* controllers = [NSArray arrayWithObjects:nv1, nv2, nv3, nil];
tabBarController.viewControllers = controllers;

这是正确的方法吗？

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
self.window = [[[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]] autorelease];


// Override point for customization after application launch.

self.tabBarController = [[[UITabBarController alloc] init] autorelease];

 self.tabBarController.viewControllers = [self initializeTabBarItems];
self.navigationController = [[UINavigationController alloc]init];
[self.navigationController setNavigationBarHidden:YES];
self.window.rootViewController = self.navigationController;
[self.navigationController pushViewController:_tabBarController animated:YES];
[self.window makeKeyAndVisible];
return YES;
}
- (NSArray *)initializeTabBarItems
{
NSArray * retval;

/* Initialize view controllers */
UIViewController *viewController1 = [[[FirstViewController alloc] initWithNibName:@"FirstViewController" bundle:nil] autorelease];
UIViewController *viewController2 = [[[SecondViewController alloc] initWithNibName:@"SecondViewController" bundle:nil] autorelease];
UIViewController *viewController3 = [[[ThirdViewController alloc]initWithNibName:@"ThirdViewController" bundle:nil]autorelease];
UIViewController *viewController4 = [[[FourthViewController alloc] initWithNibName:@"FourthViewController" bundle:nil] autorelease];
UIViewController *viewController5  = [[[FivfthViewController alloc] initWithNibName:@"FivfthViewController" bundle:nil] autorelease];


/* Initialize navigation controllers */
UINavigationController * navigationController1 = [[UINavigationController alloc] initWithRootViewController:viewController1];
UINavigationController * navigationController2 = [[UINavigationController alloc] initWithRootViewController:viewController2];
UINavigationController * navigationController3 = [[UINavigationController alloc] initWithRootViewController:viewController3];
UINavigationController * navigationController4 = [[UINavigationController alloc] initWithRootViewController:viewController4];
UINavigationController * navigationController5 = [[UINavigationController alloc] initWithRootViewController:viewController5];

/*  Release View Controllers */
[viewController1 release];
[viewController2 release];
[viewController3 release];
[viewController4 release];
[viewController5 release];

/* Stuff Navigation Controllers into return value */
retval = [NSArray arrayWithObjects:viewController1,viewController2,viewController3,viewController4,viewController5,nil];

/* Release Navigation Controllers */
[navigationController1 release];
[navigationController2 release];
[navigationController3 release];
[navigationController4 release];
[navigationController5 release];

return (retval);
}

你可以试试这个......