如何从子视图控制器中更改“后退”按钮文本？ [英] How to change Back button text from within the child view controller?

问题描述

我知道您可以在IB或 prepareForSegue 中设置后退按钮的标题，但是在我的应用程序中，我需要根据可以

I know that you can set the title of the back button from the IB or in prepareForSegue, but in my app I need to update the title according to events that can happen while the controller is visible.

我尝试了但没有任何反应：

I tried but nothing happens:

self .navigationItem.backBarButtonItem = UIBarButtonItem（title：title，style：.Plain，target：nil，action：nil）

没有后退箭头：

self.navigationItem.leftBarButtonItem = UIBarButtonItem（title：title，style：.Plain，target：nil，action： popVC）

有什么想法吗？

推荐答案

backBarButtonItem 是用于导航堆栈中 next 控制器的后退按钮的项目。

例如，如果您有一个带有根viewController A 的导航控制器，并按了viewController B ，则返回按钮那个哟您看到使用 A 配置了 B 。

The backBarButtonItem is the item used for the back button of the next controller in the navigation stack.
So for example if you have a navigation controller with a root viewController A and you push a viewController B, then the back button title that you see once B is pushed is configured using A.

您可能会遇到这样的情况：

You could have something like this :

A.navigationItem.backBarButtonItem = UIBarButtonItem(title: "Go back to A", style: .Plain, target: nil, action: nil)

一次 B 被按下，您会看到带有 Go back to A的后退按钮。

Once B is pushed, you see a back button with "Go back to A".

在您的情况下，棘手的部分是找到<$ c导航堆栈中 B 中的$ c> A 。
可以这样搜索，方法是在 navigationController 的 viewControllers 中进行搜索，如下所示：

In your case the tricky part is to find A in the navigation stack from B. You can do it by searching in the viewControllers of the navigationController like so :

// This code works from the `B` view controller
let viewControllers = self.navigationController?.viewControllers ?? []
if let indexOfCurrent = viewControllers.indexOf(self) where (indexOfCurrent > viewControllers.startIndex) {
    let indexOfPrevious = indexOfCurrent.advancedBy(-1)
    let previousViewController = viewControllers[indexOfPrevious]
    previousViewController.navigationItem.backBarButtonItem?.title = "New Title"
}

编辑

在此之后，我不知道有什么 clean 刷新导航栏的方法。

您可以做的是弹出并推送没有动画的视图控制器

I don't know any clean way to refresh the navigation bar after that. Maybe you could ask a separate question just for that.
What you could do is pop and push the view controller without animation

if let navigationController = self.navigationController {
    navigationController.popViewControllerAnimated(false)
    navigationController.pushViewController(self, animated: false)
}

或者尝试创建新的 UIBarButtonItem 而不是更改现有标题一个。

Or maybe try to create a new UIBarButtonItem instead of changing the title of the existing one.

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