如何为UINavigationBar设置背景图片

///////////////////////////////////////////////////////////////// 2012.9.6更新 （iOS 4 & iOS 5 均适用）

针对局部NavigationBar进行背景更改的方法：

float version = [[[UIDevice currentDevice] systemVersion] floatValue];
UIImage *backgroundImage = [UIImage imageNamed:@"myBackgroundImage.png"];
if (version >= 5.0) {
[self.navigationController.navigationBar setBackgroundImage:backgroundImage forBarMetrics:UIBarMetricsDefault];
}
else
{
[self.navigationController.navigationBar insertSubview:[[[UIImageView alloc] initWithImage:backgroundImage] autorelease] atIndex:1];
}

以下是全局更改NavigationBar背景的方法：

///////////////////////////////////////////////////////////////// 2012.2.24更新 （iOS 4 & iOS 5 均适用）

- (UIImage *)barBackground
{
return [UIImage imageNamed:@"topNavigationBar.png"];
}

- (void)didMoveToSuperview
{
//iOS5 only
if ([self respondsToSelector:@selector(setBackgroundImage:forBarMetrics:)])
{
[self setBackgroundImage:[self barBackground] forBarMetrics:UIBarMetricsDefault];
}
}

//this doesn't work on iOS5 but is needed for iOS4 and earlier
- (void)drawRect:(CGRect)rect
{
//draw image
[[self barBackground] drawInRect:rect];
}

@end

更详细的解决方法请参考：

http://stackoverflow.com/questions/7657465/uinavigationbars-drawrect-is-not-called-in-ios-5-0

///////////////////////////////////////////////////////////////// iOS 5之前的解决方法，在iOS 5中已经不再适用

在iPhone开发中, 有时候我们想给导航条添加背景图片, 实现多样化的导航条效果, 用其他方法往往无法达到理想的效果, 经过网上搜索及多次实验, 确定如下最佳实现方案:

 

为UINavigatonBar增加如下Category:

@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

 

 

例如, 在我的项目中, 添加如下代码:

 

/////////////////////////////////////////////////////////
/* input: The image and a tag to later identify the view */
@implementation UINavigationBar (CustomImage)
- (void)drawRect:(CGRect)rect {
UIImage *image = [UIImage imageNamed: @"title_bg.png"];
[image drawInRect:CGRectMake(0, 0, self.frame.size.width, self.frame.size.height)];
}
@end
/////////////////////////////////////////////////////////
@implementation FriendsPageViewController
// Implement viewDidLoad to do additional setup after loading the view, typically from a nib.
- (void)viewDidLoad {
self.navigationBar.tintColor = [UIColor purpleColor];

[self initWithRootViewController:[[RegPageViewController alloc] init]];
[super viewDidLoad];
}
......

 

 

实现的效果如下图: