如何从推送的控制器获取RootViewController？ [英] How do I get the RootViewController from a pushed controller?

问题描述

所以，我从RootViewController推送一个视图控制器，如：

 
 [self.navigationController pushViewController：anotherViewController animated：YES]; 
 

BUT，FROM anotherViewController 现在，我想再次访问RootViewController。 / p>

我正在尝试

 
 //（现在在anotherViewController内）
 /// RootViewController * root =（RootViewController *）self.parentViewController; // No. 
 //错误
 RootViewController * root =（RootViewController *）[self.navigationController.viewControllers objectAtIndex：0]; //是的!!它起作用
 
 

我不确定为什么这样做，我不确定它是否是最好的方法。有人可以评论一个更好的方法来从你已经推入RootViewController的navigationController的控制器中获取RootViewController，以及我的方式是否可靠？

解决方案

使用 viewControllers 属性。示例代码：

  //在另一个ViewController内部
 NSArray * viewControllers = self.navigationController.viewControllers; 
 UIViewController * rootViewController = [viewControllers objectAtIndex：viewControllers.count  -  2]; 
  

这是获取后退视图控制器的标准方式。 objectAtIndex：0 的原因是因为您尝试访问的视图控制器也是根目录，如果您在导航中更深入，后视图将不会与根视图相同。

So, I push a view controller from RootViewController like:

[self.navigationController pushViewController:anotherViewController animated:YES] ;

BUT, FROM anotherViewController now, I want to access the RootViewController again.

I'm trying

// (inside anotherViewController now)
///RootViewController *root = (RootViewController*)self.parentViewController ; // No.
// err
RootViewController *root = (RootViewController*)[self.navigationController.viewControllers objectAtIndex:0] ; // YES!! it works

I'm not sure WHY this works and I'm not sure if its the best way to do it. Can somebody comment on a better way to get the RootViewController from a controller you've pushed into that RootViewController's navigationController and whether or not the way I've done it is reliable or not?

解决方案

Use the viewControllers property of the UINavigationController. Example code:

// Inside another ViewController
NSArray *viewControllers = self.navigationController.viewControllers;
UIViewController *rootViewController = [viewControllers objectAtIndex:viewControllers.count - 2];

This is the standard way of getting the "back" view controller. The reason objectAtIndex:0 works is because the view controller you're trying to access is also the root one, if you were deeper in the navigation, the back view would not be the same as the root view.

这篇关于如何从推送的控制器获取RootViewController？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！