iOS开发笔记_3.UINavigationController层次关系

一般导航控制器含有4个对象,UINavigationController、UINavigationBar、UIViewController、UINavigationItem;

NavigationItem存放在UINavigationBar上。由下图我们可以知道一个导航控制器控制着多个视图,一个视图控制器控制一个UINavigationItem

初始化NavigationController

RootViewController *rootViewController = [[RootViewController alloc] init];

//    UINavigationController *navigationController = [[UINavigationController alloc] initWithRootViewController:rootViewController];
//    
//    [navigationController.navigationBar setBackgroundImage:[UIImage imageNamed:@"navigationbar_background.png"] forBarMetrics:UIBarMetricsDefault];
    
    NavigationViewController *navigationController = [[NavigationViewController alloc] initWithRootViewController:rootViewController];

NavigationViewController是继承了UINavigationController

 

 

NavigationBar

一个导航控制器控制多个视图,NavigationBar上的leftItem,rightItem,title是由当前的视图控制器控制的,下面看看创建的方法:

    UIBarButtonItem *leftItem = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemBookmarks target:self action:@selector(study)];
    self.navigationItem.leftBarButtonItem = leftItem;
    [leftItem release];

重点看一下,self.navigationItem.leftBarButtonItem这句话,这句话就表明了层次关系,Item是由当前视图控制器的navigationItem控制的,如果写成self.navigationController.navigationItem.leftBarButtonItem 则行不通,这就相当于给每一个视图控制器都加上了leftItem,这违反了我们的初衷!

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

这句话只能在ios5以后的版本才能使用,给navigationBar设置背景图片

 

ToolBar

ToolBar的用法和NavigationBar的用法类似,只不过ToolBar是用数组来管理的,这个很重要,并且默认是隐藏的,要使用的话记得要设置会打开。

UIBarButtonItem *tbarItem = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemAction target:self action:@selector(book)];
    
UIBarButtonItem *tbarItem1 = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemAdd target:self action:nil];
    
UIBarButtonItem *tbarItem3 = [[UIBarButtonItem alloc] initWithTitle:@"title" style:(UIBarButtonItemStyleDone) target:self action:nil];
   
 UIBarButtonItem *tbarItem4 = [[UIBarButtonItem alloc] initWithTitle:@"button1" style:(UIBarButtonItemStyleBordered) target:self action:nil];
    
    //设置间隔    
    UIBarButtonItem *flex = [[UIBarButtonItem alloc] initWithBarButtonSystemItem: UIBarButtonSystemItemFixedSpace target:self action:nil];
    
NSArray *itemArray=
@[tbarItem,flex,tbarItem1,flex,tbarItem3,flex,tbarItem4];
    
    //默认是隐藏的
    [self.navigationController setToolbarHidden:NO animated:YES];
    [self setToolbarItems:itemArray];

切记一定要打开来,不然不会显示!

 

设置navigationBar和tabBar的显示

[self.navigationController setToolbarHidden:NO animated:YES];

    [self.navigationController setNavigationBarHidden:NO animated:YES];

 

 

 

 

posted @ 2013-06-12 00:37  小木头_迪  阅读(2120)  评论(4编辑  收藏  举报