更改 UINavigationBar 背景图像

问题描述

我一直在尝试更改我的应用程序 UINavigationBar 的背景图像.我尝试了几种方法.首先，我在我的 AppDelegate 类中添加了以下代码:

I've been trying to change the background image of the UINavigationBar of my application. I tried several ways. First I added to my AppDelegate class the following code:

@implementation UINavigationBar (CustomImage)
    - (void)drawRect:(CGRect)rect {
    UIImage *image = [UIImage imageNamed: @"navigationbar.png"];
    [image drawInRect:CGRectMake(0, 0, self.frame.size.width, self.frame.size.height)];
}
@end

但它不起作用.我的下一个尝试是编写一个覆盖 drawRect 方法的 CustomizedNavigationBar 类.看起来是这样的:

But it wasn't working. My next try was to write a CustomizedNavigationBar Class which is overriding the drawRect method. It looked like that:

CustomizedNavigationBar.h

#import <UIKit/UIKit.h>

@interface CustomizedNavigationBar : UINavigationBar

@end

CustomizedNavigationBar.m

#import "CustomizedNavigationBar.h"

@implementation CustomizedNavigationBar

- (void) drawRect:(CGRect)rect {
    UIImage *image = [UIImage imageNamed: @"navigationbar.png"];
    [image drawInRect:CGRectMake(0, 0, self.frame.size.width, self.frame.size.height)];

    NSLog(@"I got called!!!!!");
}

@end

在定义 NavigationBar 的 .xib 文件中，我将类更改为新的 CustomizedNavigationBar.但它仍然无法正常工作..

In my .xib file where the NavigationBar is defined I changed the class to the new CustomizedNavigationBar. But still it is not working..

作为另一个测试，我下载了一个应该更改背景图像的示例项目.但即使使用该示例代码，它也无法正常工作.

As another test I downloaded an example project where the background image should be changed. But even with that sample code it was not working.

我做错了什么?我正在使用 IOS 5.我可以定义背景图像的任何建议或其他方式?

What am I doing wrong? I am using IOS 5. Any suggestions or other ways I could define a background image?

感谢您的回答！

推荐答案

从 iOS 5 开始你应该使用 -setBackgroundImage:forBarMetrics: 方法:

Starting in iOS 5 you should use the -setBackgroundImage:forBarMetrics: method:

[myNavbar setBackgroundImage:[UIImage imageNamed: @"UINavigationBarBackground.png"] 
               forBarMetrics:UIBarMetricsDefault];

在 Swift 4 中:

navigationBar.setBackgroundImage(UIImage(named: "UINavigationBarBackground.png"),
               for: .default)

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