一、UITabBarController对象的创建和初始化

首先创建多个视图控制器，并在tabBarItem中添加标题和图片

self.viewController.tabBarItem.title = @"首页";//设置tabBarItem标题

self.viewController.tabBarItem.image = [UIImage imageNamed:@"icon_home"];//添加图片

self.viewController.tabBarItem.badgeValue = @"1";//消息

FirstViewController *one = [[FirstViewController alloc] init];

one.tabBarItem.title = @"消息";

one.tabBarItem.image = [UIImage imageNamed:@"icon_meassage"];

SecondViewController *two = [[SecondViewController alloc] init];

two.tabBarItem.title = @"联系人";

two.tabBarItem.image = [UIImage imageNamed:@"icon_selfinfo"];

ThirdViewController *three = [[ThirdViewController alloc] init];

three.title = @"搜索";

three.tabBarItem.image = [UIImage imageNamed:@"icon_search"];

ForthViewController *four = [[ForthViewController alloc] init];

four.tabBarItem.title = @"更多";

four.tabBarItem.image = [UIImage imageNamed:@"icon_more"];

FifthViewController *five = [[FifthViewController alloc]init];

five.tabBarItem.title = @"订阅";

SixthViewController *six = [[SixthViewController alloc] init];

six.tabBarItem.title = @"下载";

UINavigationController *nav = [[UINavigationController alloc]initWithRootViewController:three];

注意，第三个视图控制器为导航控制器

将多个视图控制器添加到数组（视图超过5个以后，自动生成More，隐藏多出来的视图控制器）

效果为多出来下边一排视图切换工具

NSArray *vcArray = [NSArray arrayWithObjects:self.viewController, one, two, nav, four, five, six, nil];//创建视图控制器数组

UITabBarController *tabBarC = [[UITabBarController alloc] init];

tabBarC.tabBar.selectedImageTintColor = [UIColor redColor];//选中时图片颜色变为红色

tabBarC.viewControllers = vcArray;//将多个视图控制器组织到tab控制器中，以选项卡

self.window.rootViewController = tabBarC;//设置根视图控制器为tabBarController

二、UITabBarController可以实现UITabBarControllerDelegate协议

tabBarC.delegate = self; //设置self为代理

可以重写代理中方法（很少用），表示选中了某个ViewController

-(void)tabBarController:(UITabBarController *)tabBarController didSelectViewController:(UIViewController*)viewController{

//执行相应操作

}

//代码解说

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

{

    self.window = [[[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]] autorelease];

    FirstViewController *firstController=[[FirstViewController alloc] init];

    //设置标题

    firstController.title=@"First";

    //设置tabBarItem的样式（这种方式是按照系统定义的方式）

    firstController.tabBarItem=[[UITabBarItem alloc] initWithTabBarSystemItem:UITabBarSystemItemMoretag:101];

    //也可以用自定义方式方式如下：

    SecondViewController *secondController=[[SecondViewController alloc] init];

    secondController.title=@"Second";

    secondController.tabBarItem=[[UITabBarItem alloc] initWithTabBarSystemItem:UITabBarSystemItemHistorytag:102];

    ThirdViewController *thirdController=[[ThirdViewController alloc] init];

    thirdController.title=@"Third";

    thirdController.tabBarItem=[[UITabBarItem alloc] initWithTabBarSystemItem:UITabBarSystemItemFavoritestag:103];

    UINavigationController *nav1=[[UINavigationController alloc] initWithRootViewController:firstController];

    [firstController release];

    UINavigationController *nav2=[[UINavigationController alloc] initWithRootViewController:secondController];

    [secondController release];

    UINavigationController *nav3=[[UINavigationController alloc] initWithRootViewController:thirdController];

    [thirdController release];

    NSArray *controllersArray=[[NSArrayalloc] initWithObjects:nav1,nav2,nav3, nil];

    [nav1 release];

    [nav2 release];

    [nav3 release];

    UITabBarController *tabController=[[UITabBarController alloc] init];

    tabController.viewControllers=controllersArray;

    tabController.selectedIndex=0;

    tabController.delegate=self;//在AppDelegate.h文件内实现UITabBarControllerDelegate协议

    self.tabBarController=tabController;

    [tabController release];

    [controllersArray release];

    [self.window addSubview:tabController.view];

    [self.window makeKeyAndVisible];

    returnYES;

}

//当点击tabBarItem时触发该操作  UITabBarControllerDelegate中的一个方法

- (void)tabBarController:(UITabBarController *)tabBarController didSelectViewController:(UIViewController *)viewController {

    NSLog(@"%d", viewController.tabBarItem.tag);