NavigationController两次呈现ViewController

Question

我使用pod安装了第三方库，它有自己的navigationController。我现有的项目我在app delegate中设置了rootViewController。我是pushViewController到库ViewController（它在它自己的导航堆栈中）。当我退出然后第二次推送到库时，ViewAlready似乎就在那里，然后在顶部转换相同的视图。 在我的appDelegate中......

-(BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
    appbarViewController = [[AppBarViewController alloc] init];
    [self loadNormalFlow];
    [self.window makeKeyAndVisible];
}

- (void)loadNormalFlow
{
    self.navigation = [[UINavigationController alloc]initWithRootViewController:appbarViewController];
    self.window.rootViewController = self.navigation;
    [self.navigation setNavigationBarHidden:YES];
}

-(void)displayLibraryView
{
ACSViewController *acs = [[ACSViewController alloc] init];
            [self.navigation pushViewController:acs animated:nil];
}

在库ViewController类中返回原来的rootViewController我正在使用

[[UIApplication sharedApplication].delegate performSelector:@selector(loadNormalFlow)];

我好像没有正确地解雇库ViewController，或者它推了两次？任何的想法？