iPhone SDK开发基础之

使用UITabBarController组织和管理UIView

当你的程序分为几个相对比较独立的部分时，就比较适合使用UITabBarController来组织用户界面，如图3-26所示。

 

在屏幕的下方包含UITabBarController的三个按钮，用户单击不同的按钮即可以进入不同的界面，每个界面相对来说在整个系统中比较独立，也就是程序分成了三个相对比较独立的不同部分，在每个相对独立的部分你也可以使用UINavigationController等容器类组织你的界面。这样组织使程序逻辑非常清晰，当然你也可以组织很多个Tab而不只是三个，以下代码演示如何创建UITabBarController对象，并为其添加多个Tab。

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions: (NSDictionary *)launchOptions {   

    // Override point for customization after application launch.

 

 //Create the navigation Controller

 UINavigationController *localNavigationController;

 //Create UINavigationController

 tabBarController = [[UITabBarController alloc] init];

    tabBarController.delegate = self;

 // Create the array that will contain all the View controlelr

 NSMutableArray *localControllersArray = [[NSMutableArray alloc] init WithCapacity:3];

 // Create the view controller attached to the first item in the TabBar

 

 aViewController *firstViewController;

 firstViewController = [aViewController alloc];

 localNavigationController = [[UINavigationController alloc] initWithRoot ViewController:firstViewController];

 localNavigationController.navigationBar.barStyle = UIBarStyleBlackOpaque;

 

 [localNavigationController.tabBarItem initWithTitle:@"Outlines"

 image:[UIImage imageNamed:@"webcast.png"] tag:1];

 firstViewController.navigationItem.title = @"Outlines";

 

 [localControllersArray addObject:localNavigationController];

 [localNavigationController release];

 [firstViewController release];

 

 // Create the view controller attached to the second item in the TabBar

 

 anotherViewController *secondViewController;

 secondViewController = [[anotherViewController alloc] initWithStyle: UITableViewStyleGrouped ];

 localNavigationController = [[UINavigationController alloc] initWithRoot ViewController:secondViewController];

 [localNavigationController.tabBarItem initWithTitle:@"Q & A"

   image:[UIImage imageNamed:@"book.png"] tag:2];

  & A";

 

 [localControllersArray addObject:localNavigationController];

 [localNavigationController release];

 [secondViewController release];

  

 miscViewController *thirdViewController;

 thirdViewController = [[miscViewController alloc] initWithStyle:UITable ViewStyleGrouped ];

 localNavigationController = [[UINavigationController alloc] initWithRoot ViewController:thirdViewController];

 [localNavigationController.tabBarItem initWithTitle:@"Misc"

   image:[UIImage imageNamed:@"favorites.png"] tag:3];

 ";

 

 [localControllersArray addObject:localNavigationController];

 [localNavigationController release];

 [thirdViewController release];

 

 // load up our tab bar controller with the view controllers

 tabBarController.viewControllers = localControllersArray;

 

 // release the array because the tab bar controller now has it

 [localControllersArray release];

 // add the tabBarController as a subview in the window

 [window addSubview:tabBarController.view];

 

 // need this last line to display the window (and tab bar controller)

 [window makeKeyAndVisible];

 

    return YES;

}

捕获Tab切换事件，获取当前活动的Tab索引和UIViewController对象，代码如下。

- (void)tabBarController:(UITabBarController *)barController didSelectView Controller:(UIViewController *)viewController{

 

 NSLog(@"currentController index:%d"，viewController， tabBarController.selectedIndex);

 UIViewController  *currentController = tabBarController.selectedView Controller;

 NSLog(@"currentController: %@"，currentController);

   

}

切换不同的Tab时，只需要设置UITabBarController的selectedIndex属性即可，代码如下。

tabBarController.selectedIndex = 2;

本节相关的完整Xcode工程源代码文件请参考本书附带的光盘中的Lessons2实例。

本文节选自《iOS软件开发揭密：iPhone&iPad企业应用和游戏开发》一书。

《iOS软件开发揭密：iPhone&iPad企业应用和游戏开发》一书已由电子工业出版社正式出版，本书由虞斌著

。

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