IOS-Navigation的添加（RootViewController）

添加Nav方法：

在AppDelegate中

.h文件

@property (strong, nonatomic) UINavigationController *navC;

.m文件  

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions

添加方法2种如下：

1 、self.navC = [[[UINavigationControlleralloc] init] autorelease];

    [self.navCpushViewController:self.viewControlleranimated:YES];

    self.window.rootViewController = self.navC;

2、会有提示信息：

Application windows are expected to have a root view controller at the end of application launch

程序运行正常，尚未知道有何影响。

    self.navC = [[UINavigationControlleralloc] initWithRootViewController:self.viewController];

    [self.windowaddSubview:self.navC.view];