学习笔记：UINavigationbar的背景修改方法集合

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 }

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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];

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此代码效果图如下：



这一方法转载自：/article/5601614.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

复制代码
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

复制代码
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：/article/5601615.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