最近我突然发现UINavigationbar背景修改的方法不起作用了，代码如下：

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@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

发现原来是iOS 5的原因，如果运行在iOS 5以下的版本就没有问题了。经过实验以下方法适合iOS 5（放在ViewDidLoad中）：

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    if ([self.navigationController.navigationBar respondsToSelector:@selector( setBackgroundImage:forBarMetrics:)]){
        [self.navigationController.navigationBar setBackgroundImage:[UIImage imageNamed:@"navigationbar.png"] forBarMetrics:UIBarMetricsDefault];
    }

第一条if语句的作用是防止程序在iOS 5以下的版本中崩溃。

这样，依靠这两段代码，我的UINavigationbar的背景问题在iOS 5及以下版本中得到了完美的解决。


 

iOS5之前是如何自定义UINavigationBar背景的？

在iOS5.0中我们可以非常简单的设置UINavigationBar的背景（setBackgroundImage: forBarMetrics:方法），而这对于之前的版本是不可同日而语的。通过网络收集整理了一下以前的各种方式，只能作为学习笔记做个记录，菜鸟学习而已。高人就跳过吧。
方法一：主要技巧就是用视图的drawInRect:方法绘制
如下为创建了一个UINavigationBar Category

// 其实现代码如下
@implementation UINavigationBar (UINavigationBarCategory)
 
 - (void)drawRect:(CGRect)rect {
     //颜色填充
     UIColor *color = [UIColor redColor];
     CGContextRef context = UIGraphicsGetCurrentContext();
     CGContextSetFillColor(context,CGColorGetComponents([color CGColor]));
     CGContextFillRect(context,rect);
     self.tintColor = color;
 
     //图片填充
     UIColor *color = [UIColor colorWithRed:46.0f/255.0f green:87.0f/255.0f blue:29.0f/255.0f alpha:1.0f];
     UIImage *img = [UIImage imageNamed:@"bg.png"];
     [img drawInRect:CGRectMake(0,0,self.frame.size.width,self.frame.size.height)];
     self.tintColor = color;
 }
 @end

自定义图片背景以下两句代码是关键：
UIImage *img = [UIImage imageNamed:@"bg.png"];

[img drawInRect:CGRectMake(0,0,self.frame.size.width,self.frame.size.height)];
或者：
UIImage *img = [UIImage imageNamed:@"bg.png"];
CGPoint point = {0,0};
[img drawAtPoint:point];
或者：

//加入旋转坐标系代码

 

// Drawing code

 

UIImage *navBarImage = [UIImage imageNamed:@"LOGO_320×44.png"];

 

CGContextRef context = UIGraphicsGetCurrentContext();

 

CGContextTranslateCTM(context, 0.0, self.frame.size.height);

 

CGContextScaleCTM(context, 1.0, -1.0);

 

CGPoint center=self.center;

 

CGImageRef cgImage= CGImageCreateWithImageInRect(navBarImage.CGImage,CGRectMake(0, 0, 1, 44));

 

CGContextDrawImage(context, CGRectMake(center.x-160-80, 0, 80,self.frame.size.height), cgImage);

 

CGContextDrawImage(context, CGRectMake(center.x-160, 0, 320,self.frame.size.height), navBarImage.CGImage);

 

CGContextDrawImage(context, CGRectMake(center.x+160, 0, 80,self.frame.size.height), cgImage);
扩展UINavigationBar的drawRect方法的这种自定义方法会影响到工程项目中所有的导航条栏。
类似在iOS5.0中，由于UINavigationBar、UIToolBar和UITabBar的实现方式改变，而drawRect:方法不会被调用了，所以就不支持这种通过定义导航条类别的方式来自定义导航条了。除非在这类控件的子类中实现。

//子类可以调用drawRect:方法
@interface MyNavigationBar : UINavigationBar
 @end
 @implementation MyNavigationBar
 - (void)drawRect:(CGRect)rect {
 　　[super drawRect:rect];
 }
 @end

方法二：定义UINavigationBar的一个static函数

 1 + (UINavigationBar *)createNavigationBarWithBackgroundImage:(UIImage *)backgroundImage title:(NSString *)title {
  2       UINavigationBar *customNavigationBar = [[[UINavigationBar alloc] initWithFrame:CGRectMake(0, 0, 320, 44)] autorelease];
  3       UIImageView *navigationBarBackgroundImageView = [[UIImageView alloc] initWithImage:backgroundImage];
  4       [customNavigationBar addSubview:navigationBarBackgroundImageView];
  5       UINavigationItem *navigationTitle = [[UINavigationItem alloc] initWithTitle:title];
  6       [customNavigationBar pushNavigationItem:navigationTitle animated:NO];
  7       [navigationTitle release];
  8       [navigationBarBackgroundImageView release];
  9       return customNavigationBar;
 10 }

下面是在需要生成UINavgationBar 的地方添加的代码     *ViewController.m：

View Code 
 1 self.navigationController.navigationBar.hidden = YES;
  2 UIImage *navigationBarBackgroundImage =[UIImage imageWithContentsOfFile:[[NSBundle mainBundle] pathForResource:@"topbar-bg" ofType:@"png"]];
  3 UINavigationBar *customNavigationBar = [YOUR_Util_Class createNavigationBarWithBackgroundImage:navigationBarBackgroundImage title:nil];
  4 [self.view addSubview:customNavigationBar];
  5 
  6 UIButton *backButton = [[UIButton alloc] initWithFrame:CGRectMake(0.0, 0.0, 75.0, 30.0)];
  7 if (_backButtonImage) {
  8        [backButton setImage:_backButtonImage forState:UIControlStateNormal];
  9 }else {
 10        [backButton setImage:[UIImage imageNamed:@"btnback.png"] forState:UIControlStateNormal];
 11 }
 12 
 13 [backButton addTarget:self action:@selector(backButtonCliked:) forControlEvents:UIControlEventTouchUpInside];
 14 UIBarButtonItem *backBarButton = [[UIBarButtonItem alloc] initWithCustomView:backButton];
 15 customNavigationBar.topItem.leftBarButtonItem = backBarButton;
 16 
 17 [backButton release];
 18 [backBarButton release];
 19 
 20 UIButton *addButton = [[UIButton alloc] initWithFrame:CGRectMake(0, 0, 43, 30)];
 21 UIBarButtonItem *addBarButton = [[UIBarButtonItem alloc] initWithCustomView:addButton];
 22 if (_isFromFavorites) {
 23        [addButton setImage:[UIImage imageNamed:@"btn-delete-0.png"] forState:UIControlStateNormal];
 24        [addButton addTarget:self action:@selector(deleteButtonClicked:) forControlEvents:UIControlEventTouchUpInside];
 25 }else {
 26         [addButton setImage:[UIImage imageNamed:@"btn_add.png"] forState:UIControlStateNormal];
 27         [addButton addTarget:self action:@selector(addButtonClicked:) forControlEvents:UIControlEventTouchUpInside];
 28 }
 29 customNavigationBar.topItem.rightBarButtonItem = addBarButton;
 30 [addButton release];
 31 [addBarButton release];

此代码效果图如下：


这一方法转载自：http://www.cnblogs.com/moshengren/archive/2010/10/18/1855191.html

方法三：也是自定义导航条类别，但是重写setBackgroundImage:方法
CustomNavController.h

 1 //  Created by suruiqiang on 8/3/10.
 2 //  Copyright 2010 __MyCompanyName__. All rights reserved.
 3 //
 4 #pragma once
  5 #import <UIKit/UIKit.h>
  6 @interface UINavigationBar (UINavigationBarCategory) 
  7 UIImageView *bg;
  8 -(UINavigationBar*)setBackgroundImage:(UIImage*)image;
  9 - (void)insertSubview:(UIView *)view atIndex:(NSInteger)index;
 10 @end

CustomNavController.m

 1 #import "CustomerNavBarController.h"
  2 
  3 @implementation UINavigationBar (UINavigationBarCategory)
  4 -(UINavigationBar*)setBackgroundImage:(UIImage*)image
  5 {
  6     UINavigationBar *NavBar = [[UINavigationBar alloc] initWithFrame:CGRectMake(0, 0, 320, 44)];
  7     if(image == nil) return NavBar;
  8     bg = [[UIImageView alloc]initWithImage:image];
  9     bg.frame = CGRectMake(0.f, 0.f, self.frame.size.width, self.frame.size.height);
 10     [NavBar addSubview:bg];
 11     [NavBar sendSubviewToBack:bg];
 12     [bg release];
 13     return NavBar;
 14 }
 15 
 16 - (void)insertSubview:(UIView *)view atIndex:(NSInteger)index
 17 {
 18     [super insertSubview:view atIndex:index];
 19     [self sendSubviewToBack:bg];
 20 }
 21 @end

调用代码示例：

- (void)viewDidLoad {
    [super viewDidLoad];
    [[self.navigationController navigationBar] setBackgroundImage:[UIImage imageNamed:@"NavigationBarBackground.png"]];
 
 //在下面添加你自己的功能代码
***********
 }

此方法转载自：http://www.cnblogs.com/moshengren/archive/2010/10/18/1855202.html

方法四：通过导入QuartzCore框架绘制CALayer层来自定义

#import <QuartzCore/QuartzCore.h>
 
 @interface DDNavigationViewController : UINavigationController<UINavigationControllerDelegate> {
 
     CALayer *_barBackLayer;
 
 }
 
 @end

 

View Code 
 1 @implementation DDNavigationViewController
  2 
  3 - (id)initWithRootViewController:(UIViewController *)rootViewController {
  4 
  5     self = [super initWithRootViewController:rootViewController];
  6 
  7     self.delegate = self;
  8 
  9     return self;
 10 
 11 }
 12 
 13 - (void)loadView {
 14 
 15     [super loadView];
 16 
 17     UINavigationBar *bar = self.navigationBar;
 18 
 19     CALayer*layer = [CALayer layer];
 20 
 21     UIImage *navBarImage = [UIImage imageNamed:@"navigationBarBackground.png"];
 22 
 23     layer.contents = (id)navBarImage.CGImage;
 24 
 25     layer.frame= CGRectMake(0, 0, 320, navBarImage.size.height);
 26 
 27     [bar.layer insertSublayer:layer atIndex:0];
 28 
 29     _barBackLayer = layer;
 30 
 31 }  
 32 
 33 
 34 #pragma mark -
 35 
 36 #pragma mark UINavigationControllerDelegate
 37 
 38 - (void)navigationController:(UINavigationController *)navigationController didShowViewController:(UIViewController *)viewController animated:(BOOL)animated {
 39 
 40     [_barBackLayer removeFromSuperlayer];
 41 
 42     [navigationController.navigationBar.layer insertSublayer:_barBackLayeratIndex:0];
 43 
 44 }
 45 
 46 @end