恢复RootViewController的原始状态

Question

我正在构建一个静态库，为不同的应用程序提供UI内容，每当我动态设置app delegate的窗口rootviewcontroller时，我需要知道如何恢复它而不会丢失所有显示的视图控制器。我们说我有这个代码

@interface SampleViewController : UIViewController{
    UIViewController *_originalRootViewController;
}
...
-(IBAction)openSomething:(id)sender{
    UIWindow * window = [[UIApplication sharedApplication] delegate] window];
    _originalRootViewController = window.rootViewController;
    window.rootViewController = self;
}

-(IBAction)closeSomething:(id)sender{
    UIWindow * window = [[UIApplication sharedApplication] delegate] window];
    //PROBLEM, doing this shows the first view of the app instead of the latest view controller that was pushed on the view hierarchy
    window.rootViewController = _originalRootViewController;
}

有关如何解决此问题的任何建议？在我提出另外一个关于使用2个UIWindows的问题之前，其他人告诉我只使用1个UIWindow，尽管我告诉他因为这个问题不可能。