UINavigationBar：外观有效但不是UINavigationBar：appearanceWhenContained in [英] UINavigationBar:appearance works but not UINavigationBar:appearanceWhenContained in

问题描述

我需要将导航栏设置为自定义颜色，以下代码将执行此操作：

I have a requirement to set the navigation bar to a custom color and this following code will do that:

[[UINavigationBar appearance]
            setBackgroundImage:navigationBarTileImage forBarMetrics:UIBarMetricsDefault];

然而，我的应用程序调用系统MFMailComposeViewController和MFMessageComposeViewController，我希望导航栏成为默认颜色那些观点，所以我这样做了：

However my application invokes the system MFMailComposeViewController and MFMessageComposeViewController and I want the navigation bar to be the default color for those views, so I did this:

[[UINavigationBar appearanceWhenContainedIn: [MyViewControllerBase class], [MyViewController1 class], [MyViewController2 class], nil]
    setBackgroundImage:navigationBarTileImage forBarMetrics:UIBarMetricsDefault];

但是现在导航栏不再具有我的默认颜色。
为什么appearanceWhenContainedIn不工作？

However now the navigation bar no longer has my default color. Why is appearanceWhenContainedIn not working?

推荐答案

的参数appearanceWhenContainedIn：表示视图（和/或视图控制器）包含层次结构，而不是可能容器的列表。 （不可否认，文档不是不清楚这一点。请参阅来自WWDC 2011的视频。）因此，

The argument to appearanceWhenContainedIn: represents a view (and/or view controller) containment hierarchy, not a list of possible containers. (Admittedly, the docs aren't clear on this. See the video from WWDC 2011.) Thus,

[UINavigationBar appearanceWhenContainedIn:[NSArray arrayWithObjects:[MyViewControllerBase class], [MyViewController1 class], [MyViewController2 class], nil]]

为您提供 UINavigationBar 包含在 MyViewControllerBase 中，而 MyViewController1 位于 MyViewController2 。我猜这不是你拥有的包容层次结构。

gives you an appearance proxy for a UINavigationBar contained within a MyViewControllerBase, which in turn is within a MyViewController1 inside a MyViewController2. I'm guessing that's not the containment hierarchy you have.

相反，请查看包含导航栏的视图控制器。它可能是一个通用的 UINavigationController ...但你不能只做

Instead, look at the view controller which contains your navigation bar. It's probably a generic UINavigationController... but you can't just do

[UINavigationBar apperanceWhenContainedIn:[NSArray arrayWithObject:[UINavigationController class]]]

因为那样你就会获得邮件/消息控制器。遗憾的是，当你可以在邮件/邮件视图控制器中获取 UINavigationBar 的外观代理时，没有办法告诉你它可以撤消在更通用级别上进行的外观更改。

because then you'll get the mail/message controllers too. And sadly, while you can get at the appearance proxy for a UINavigationBar within a mail/message view controller, there isn't a way to tell it to undo appearance changes made at a more generic level.

看起来这种情况的通常解决方案是让自己成为 UINavigationController 子类，并将其用于您想要换肤的UI部分。子类可以为空 - 它仅用于识别UI的部分 appearanceWhenContainedIn：。 （同时， MFMailComposeViewController 之类的东西继续使用默认外观，因为它们仍然使用泛型 UINavigationController 。）

It looks like the usual solution to such scenarios is to make yourself a UINavigationController subclass, and use it for the parts of your UI you want skinned. The subclass can be empty -- it only exists to identify parts of your UI for appearanceWhenContainedIn:. (Meanwhile, things like MFMailComposeViewController continue to use the default appearance because they still use the generic UINavigationController.)

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