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 @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 {
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5 self = [super initWithRootViewController:rootViewController];
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7 self.delegate = self;
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9 return self;
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11 }
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13 - (void)loadView {
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15 [super loadView];
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17 UINavigationBar *bar = self.navigationBar;
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19 CALayer*layer = [CALayer layer];
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21 UIImage *navBarImage = [UIImage imageNamed:@"navigationBarBackground.png"];
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23 layer.contents = (id)navBarImage.CGImage;
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25 layer.frame= CGRectMake(0, 0, 320, navBarImage.size.height);
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27 [bar.layer insertSublayer:layer atIndex:0];
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29 _barBackLayer = layer;
30
31 }
32
33
34 #pragma mark -
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36 #pragma mark UINavigationControllerDelegate
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38 - (void)navigationController:(UINavigationController *)navigationController didShowViewController:(UIViewController *)viewController animated:(BOOL)animated {
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40 [_barBackLayer removeFromSuperlayer];
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42 [navigationController.navigationBar.layer insertSublayer:_barBackLayeratIndex:0];
43
44 }
45
46 @end