UINavigationBar setBackgroundImage：forBarMetrics：Not Working [英] UINavigationBar setBackgroundImage: forBarMetrics: Not Working

问题描述

我只是切换到iOS 5，除了自定义导航栏，一切似乎都在我的应用程序工作。我环顾四周，并遵循每个人的建议，调用新的方法setBackgroundImage：forBarMetrics：但它似乎不工作。这是我试图放置在应用程序委托和一些视图控制器的viewDidLoad方法内的代码：

I just switched over to iOS 5 and everything appears to be working in my application aside from the custom navigation bar. I looked around and followed everybody's suggestion of calling the new methods setBackgroundImage: forBarMetrics: however it doesn't appear to work. This is the code I've tried to place both within the app delegate and within the viewDidLoad method of some of the view controllers:

UINavigationBar *nb = [[UINavigationBar alloc]init];
if( [nb respondsToSelector:@selector(setBackgroundImage:forBarMetrics:)] )
{
    UIImage *image = [UIImage imageNamed:@"navBarBackground.png"];
    [nb setBackgroundImage:image forBarMetrics:UIBarMetricsDefault];
}
[nb release];

不幸的是这不行。

推荐答案

要应用 image code>到所有导航栏，使用外观代理：

To apply image to all your navigation bars, use the appearance proxy:

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

个别酒吧：

// Assuming "self" is a view controller pushed on to a UINavigationController stack
[self.navigationController.navigationBar setBackgroundImage:image forBarMetrics:UIBarMetricsDefault];

在您的示例中，背景图片将不会更改，因为 nb 没有连接到任何东西。

In your example, the background image won't change because nb isn't hooked up to anything.

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