将navigationBar的返回按钮的title改为back

很多时候我们使用navigationController时由于上一个navigationController.title的字符串太长，而导致下一个界面的返回按钮变的很长也很难看，为了美观我们我们可以把返回按钮的title改为back，或者是用自定义的图片。 

    1.把返回按钮的title改为back：这里要特别说明一下，需要在上一个viewController里面写上以下代码。若是在当前viewController中无论你是用self.navigationItem.leftBarButtonItem.title = @"back"; 还是用self.navigationItem.backBarButtonItem.title = @"back"; 都不会修改返回按钮的title。代码如下： 

Objective-c代码  

1. - (void)back:(id)sender {  
2.     [self.navigationController popViewControllerAnimated:YES];  
3. }  
4.   
5.  // The designated initializer.  Override if you create the controller programmatically and want to perform customization that is not appropriate for viewDidLoad.  
6. - (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil {  
7.     if (self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil]) {  
8.         // 下一个界面的返回按钮  
9.         UIBarButtonItem *temporaryBarButtonItem = [[UIBarButtonItem alloc] init];  
10.         temporaryBarButtonItem.title = @"back";  
11.         temporaryBarButtonItem.target = self;  
12.         temporaryBarButtonItem.action = @selector(back:);  
13.         self.navigationItem.backBarButtonItem = temporaryBarButtonItem;  
14.         [temporaryBarButtonItem release];  
15.     }  
16.     return self;  
17. }  

    2.用自定义的图片修改返回按钮： 

Objective-c代码  

1. -(IBAction)backAction{  
2.     [self.navigationController popViewControllerAnimated:YES];  
3. }  
4.   
5.  // The designated initializer.  Override if you create the controller programmatically and want to perform customization that is not appropriate for viewDidLoad.  
6. - (id)initWithNibName:(NSString *)nibNameOrNil bundle:(NSBundle *)nibBundleOrNil {  
7.     if (self = [super initWithNibName:nibNameOrNil bundle:nibBundleOrNil]) {  
8.         // Custom initialization  
9.         UIButton *backButton = [UIButton buttonWithType:UIButtonTypeCustom];  
10.         backButton.frame = CGRectMake(0.0, 0.0, 40.0, 27.0);  
11.         [backButton setImage:[UIImage imageNamed:@"Btn_Back_Off.png"] forState:UIControlStateNormal];  
12.         [backButton setImage:[UIImage imageNamed:@"Btn_Back_On.png"] forState:UIControlStateSelected];  
13.         [backButton addTarget:self action:@selector(backAction) forControlEvents:UIControlEventTouchUpInside];  
14.         UIBarButtonItem *temporaryBarButtonItem = [[UIBarButtonItem alloc] initWithCustomView:backButton];  
15.         temporaryBarButtonItem.style = UIBarButtonItemStylePlain;  
16.         self.navigationItem.leftBarButtonItem=temporaryBarButtonItem;  
17.         [temporaryBarButtonItem release];         
18.     }  
19.     return self;  
20. }