问题描述

我在 iOS4 的应用程序中使用自定义 drawRect 函数在 UINavigationBar 上绘图，它不使用图像，仅使用 CoreGraphics.

I'm using a custom drawRect function to draw on UINavigationBar across my application in iOS4, it doesn't use images, only CoreGraphics.

由于iOS5的UINavigationBar类中无法实现drawRect，Apple建议继承UINavigationBar.

Since you can't implement drawRect in UINavigationBar category in iOS5, Apple is suggesting to subclass UINavigationBar.

当 navigationBar 时，如何用我在 UINavigationController 中的子类替换 UINavigationBar (因此它将与 iOS4 和 iOS5 兼容)code> 属性是只读的?

How is it possible to replace the UINavigationBar with my subclass in UINavigationController (so it'll be compatible with iOS4 and iOS5) when the navigationBar property is read only?

@property(nonatomic, readonly) UINavigationBar *navigationBar

我根本没有在我的应用程序中使用 XIB，因此无法将 UINavigationBar 添加到 NIB 并通过 InterfaceBuilder 更改类.

I'm not using XIBs in my application at all, so adding a UINavigationBar to a NIB and changing the class via InterfaceBuilder is not an option.

推荐答案

从 iOS6 开始，通过使用 UINavigationControllers 方法 initWithNavigationBarClass 可以非常简单地完成此任务，而无需打乱其他类:toolbarClass:

As of iOS6, this is now quite simple to accomplish without swizzling or messing with other classes by using UINavigationControllers method initWithNavigationBarClass:toolbarClass:

- (id)initWithNavigationBarClass:(Class)navigationBarClass 
                    toolbarClass:(Class)toolbarClass;

来自文档:

初始化并返回一个新创建的导航控制器使用您的自定义栏子类.

Initializes and returns a newly created navigation controller that uses your custom bar subclasses.

_{针对 iOS6 更新了答案.}

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