如何正确刷新UINavigationBar？ [英] How to properly refresh a UINavigationBar?

问题描述

关于此问题：如何在子视图控制器中更改后退按钮文本？我正在使用 previousViewController.navigationItem.backBarButtonItem？更改后退按钮标题之后，寻找一种刷新导航栏的适当方法。 title =新标题 。

In relation to this question: How to change Back button text from within the child view controller? I am searching for a propery way to refresh the navigation bar after changing the back button title with previousViewController.navigationItem.backBarButtonItem?.title = "New Title".

链接问题的解决方案（不太理想？）：

The (not so ideal?) solution from the linked question:

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

编辑：

显然更改图层框架会强制导航栏刷新。不是解决方案，而是一种更便宜的解决方法（我）：

Apparently changing the layer frame forces the navigation bar to refresh. Not a solution, but a less expensive(?) workaround I guess:

if let navigationController = self.navigationController {
    navigationController.navigationBar.layer.frame.insetInPlace(dx: 0.1, dy: 0)
    navigationController.navigationBar.layer.frame.insetInPlace(dx: -0.1, dy: 0)
}

推荐答案

尝试各种刷新方法后，我发现这是最难看的似乎有效的解决方案（当时在iOS 10 上，但目前在iOS 13上显然不可用，即不要指望此）：

After trying various methods to refresh, I find this is the least ugly solution that seems to work (back then on iOS 10 but apparently not currently on iOS 13, i.e., don't count on this):

guard let navigation = navigationController,
      !(navigation.topViewController === self) else {
    return
}
let bar = navigation.navigationBar
bar.setNeedsLayout()
bar.layoutIfNeeded()
bar.setNeedsDisplay()

尝试了其他方法：

• 呈现视图控制器（导致屏幕闪烁


• 隐藏并重新显示该条（如果在向后滑动到以前的VC之间有一半，则会中断条）


• 设置条的图层框架（似乎不能可靠地工作，并且 navigationBar 的文档明确禁止使用）

• Presenting a view controller (causes screen to flicker in some cases)
• Hiding and re-showing the bar (breaks bar if half-way between backswipe to previous VC)
• Setting the bar's layer's frame (does not seem to work reliably, and is explicitly forbidden by the documentation for navigationBar)

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