IOS ViewController 导航路径 - 如何以编程方式向后导航

IOS ViewController navigation path - how to navigate back programatically

提问by mpprdev

I'm using IOS5 Storyboard. My View Controller path is as follows:

我正在使用 IOS5 故事板。我的视图控制器路径如下：

tabbarVC --> navigationVC-1 --> tableVC-1 --(via segue push)-> tableVC-2 --(via segue modal)-> navigationVC-2 --> tableVC-3

In the cancel button callback action method in tableVC-3 I call [self dismissViewControllerAnimated:YES completion:nil];that successfully gets me back to tableVC-2. However when I try to examine the navigation path backwards in the debugger, I don't see a way to access tableVC-2 from navigationVC-2. I expected navigationVC-2 to maintain a link to tableVC-2 or navigationVC-1 but it doesn't seem to. Please see my debugger output below.

在 tableVC-3 中的取消按钮回调操作方法中，我调用[self dismissViewControllerAnimated:YES completion:nil];它成功让我回到 tableVC-2。但是，当我尝试在调试器中向后检查导航路径时，我没有看到从 navigationVC-2 访问 tableVC-2 的方法。我希望 navigationVC-2 保持指向 tableVC-2 或 navigationVC-1 的链接，但它似乎没有。请在下面查看我的调试器输出。

Can someone explain the navigation hierarchy and how to traverse the chain backwards programatically?

有人可以解释导航层次结构以及如何以编程方式向后遍历链吗？

(gdb) po self
<tableVC-3: 0x6d33340>

(gdb) po (UIViewController*) [self navigationController]
<UINavigationController: 0x6d33560>

(gdb) po (UIViewController*)[[self navigationController] navigationController]
Can't print the description of a NIL object.

(gdb) po (UIViewController*)[[self navigationController] topViewController]
<tableVC-3: 0x6d33340>

(gdb) po (UIViewController*)[[self navigationController] presentingViewController]
<UITabBarController: 0x6b2eba0>

(gdb) po (UIViewController*)[[self navigationController] presentedViewController]
Can't print the description of a NIL object.

(gdb) po (UIViewController*)[[self navigationController] visibleViewController]
<tableVC-3: 0x6d33340>

回答by Mike Gledhill

This is an old question, but just to help anyone else who comes across this issue, there's a single command which'll make your life easier..

这是一个老问题，但只是为了帮助遇到此问题的其他人，有一个命令可以让您的生活更轻松..

[self.navigationController popToRootViewControllerAnimated:TRUE];

Easy when you stumble across the right command, isn't it !

当您偶然发现正确的命令时很容易，不是吗！

So, supposing you had a series of three screens in a Navigation Controller, and on the thirdscreen you wanted the "Back" button to take you back to the initialscreen.

因此，假设您在导航控制器中有一系列三个屏幕，并且在第三个屏幕上您希望“返回”按钮将您带回初始屏幕。

-(void)viewDidLoad
{
    [super viewDidLoad];

    // change the back button and add an event handler
    self.navigationItem.leftBarButtonItem =
    [[UIBarButtonItem alloc] initWithTitle:@"Back"
                                     style:UIBarButtonItemStyleBordered
                                    target:self
                                    action:@selector(handleBack:)];
}


-(void)handleBack:(id)sender
{
    NSLog(@"About to go back to the first screen..");
    [self.navigationController popToRootViewControllerAnimated:TRUE];
}

回答by Adam Knights

After some research using this and a couple other questions for modal UIViewControllers in storyboard to go back two views I used

在使用这个和一些其他关于情节提要中的模态 UIViewControllers 的问题进行一些研究后，返回我使用的两个视图

[self.presentingViewController.presentingViewController dismissViewControllerAnimated:YES completion:nil];

回答by Vincent Bernier

Going throw an old response tough of updating it to be more complet.
To address this question :

将抛出一个旧的响应，很难更新它以使其更加完整。
要解决这个问题：

Can someone explain the navigation hierarchy and how to traverse the chain backwards programatically?

有人可以解释导航层次结构以及如何以编程方式向后遍历链吗？

The structure of your navigation :

您的导航结构：

tabbarVC --> navigationVC-1 --> tableVC-1 --(via segue push)-> tableVC-2 --(via segue modal)-> navigationVC-2 --> tableVC-3

tabbarVC --> navigationVC-1 --> tableVC-1 --(通过segue push)-> tableVC-2 --(通过segue modal)-> navigationVC-2 --> tableVC-3

Can be explain like this :
The TabbarVC is showing it's 'selectedViewController' (navigationVC-1).
NavigationVC-1 has its navigation stack compose of TableVC-1 and TableVC-2 (topViewController of NavigagtionVC-1)
Then NavigationVC-2 is presented Modally over the tabbarVC, so tabbarVC is the presentingViewControllerand NavigationVC-2 is the presentedViewController

可以这样解释：
TabbarVC 显示它是“selectedViewController”（navigationVC-1）。
NavigationVC-1 的导航堆栈由 TableVC-1 和 TableVC-2（NavigagtionVC-1 的 topViewController）组成，
然后 NavigationVC-2 以模态呈现在 tabbarVC 上，因此 tabbarVC 是presentingViewControllerNavigationVC-2 是presentedViewController

So in order to reach tableVC-2 from tableVC-3 you would need to do something like this :

因此，为了从 tableVC-3 到达 tableVC-2，您需要执行以下操作：

[(UINavigationController *)[(UITabBarController *)[tableVC-3 presentingViewController] selectedViewController] topViewController];

(don't do that in production code)

（不要在生产代码中这样做）

[tableVC-3 presentingViewController]as well as [tableVC-3.navigationController presentingViewController]will give you back the UITabBarController.

[tableVC-3 presentingViewController]以及[tableVC-3.navigationController presentingViewController]会给你回UITabBarController。

---

---

If you are using a UINavigationControlleryou should use it's pushand popmethod to put UIViewController on or off the "presentation stack".
You will be able to access the UINavigationControllerfrom those UIViewControllerlike this:

如果您正在使用UINavigationController，您应该使用它的push和pop方法将 UIViewController 放在或关闭“演示堆栈”。
您将能够UINavigationController从这样的人访问UIViewController：

self.navigationController

If you want to go back more than one UIViewControlleron the "presentation stack" you can use this method on the UINavigationController

如果您想UIViewController在“演示堆栈”上返回多个，您可以在UINavigationController

popToViewController:animated:
Pops view controllers until the specified view controller is at the top of the navigation stack.
- (NSArray *)popToViewController:(UIViewController *)viewController animated:(BOOL)animated

popToViewController:animated：弹出
视图控制器，直到指定的视图控制器位于导航堆栈的顶部。
- (NSArray *)popToViewController:(UIViewController *)viewController animation:(BOOL)animated

---

---

To dismiss a UIViewControllerthat was presented modally, the UIViewControllerthat have presented it need to dismiss it with :

要关闭以模态呈现的UIViewController，已经呈现的UIViewControllerUIViewController需要关闭它：

- (void)dismissModalViewControllerAnimated:(BOOL)animated

So in this case it should be :

所以在这种情况下它应该是：

[tableVC-2 dismissModalViewControllerAnimated:YES];

回答by Suragch

Swift

迅速

If you are using a navigation controller the you can navigate back to the previous view controller with

如果您使用的是导航控制器，则可以使用以下命令导航回上一个视图控制器

self.navigationController?.popViewControllerAnimated(true)

or back to the root view controller with

或返回根视图控制器

self.navigationController?.popToRootViewControllerAnimated(true)