tab bar controller

下面记一下怎样通过代码的方式为选项卡添加视图。

1、创建一个基于Empty Application的项目

2、创建两个新类，基类选择UIViewController，勾选With XIB for user interface分别命名为"OneController'和"TwoController",

3、分别更改OneController.xib和TwoController.xib文件的view背景颜色，便于区分

4、在AppDelegate.m文件中的 - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions{ }函数做如下修改（记得导入OneController和TwoController的头文件）

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    self.window = [[[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]] autorelease];

    //将tabBar(选项卡)添加进来
    UITabBarController *tabBarController = [[[UITabBarController alloc] init] autorelease];

    //为选项卡添加子控制器
    OneController *one = [[[OneController alloc] init] autorelease];
    [tabBarController addChildViewController:one];

    TwoController *two = [[[TwoController alloc] init] autorelease];
    [tabBarController addChildViewController:two];



    self.window.rootViewController = tabBarController;

    [self.window makeKeyAndVisible];
    return YES;
}

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    self.window = [[[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]] autorelease];

    //将tabBar(选项卡)添加进来
    UITabBarController *tabBarController = [[[UITabBarController alloc] init] autorelease];
    
    //为选项卡添加子控制器
    OneController *one = [[[OneController alloc] init] autorelease];
    [tabBarController addChildViewController:one];
    
    TwoController *two = [[[TwoController alloc] init] autorelease];
    [tabBarController addChildViewController:two];
    
    
    
    self.window.rootViewController = tabBarController;
    
    [self.window makeKeyAndVisible];
    return YES;
}

运行效果如下：

现在创建好的选项卡下面是没有图标和文字的，，，现在我们通过代码给它们添加一些图标和文字，注意，，选项卡的图标和文字是子控制器决定的而不是tab Bar Controller，，这点要记住。

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    self.window = [[[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]] autorelease];

    //将tabBar(选项卡)添加进来
    UITabBarController *tabBarController = [[[UITabBarController alloc] init] autorelease];

    //为选项卡添加子控制器
    OneController *one = [[[OneController alloc] init] autorelease];
    one.tabBarItem = [[[UITabBarItem alloc] initWithTabBarSystemItem:UITabBarSystemItemDownloads tag:0] autorelease];//增加系统自带的下载图标
    [tabBarController addChildViewController:one];

    TwoController *two = [[[TwoController alloc] init] autorelease];
    //添加一个自定义的图标和文字
    two.tabBarItem.title = @"two";
    two.tabBarItem.image = [UIImage imageNamed:@"success.png"];
    [tabBarController addChildViewController:two];



    self.window.rootViewController = tabBarController;

    [self.window makeKeyAndVisible];
    return YES;
}

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    self.window = [[[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]] autorelease];

    //将tabBar(选项卡)添加进来
    UITabBarController *tabBarController = [[[UITabBarController alloc] init] autorelease];
    
    //为选项卡添加子控制器
    OneController *one = [[[OneController alloc] init] autorelease];
    one.tabBarItem = [[[UITabBarItem alloc] initWithTabBarSystemItem:UITabBarSystemItemDownloads tag:0] autorelease];//增加系统自带的下载图标
    [tabBarController addChildViewController:one];
    
    TwoController *two = [[[TwoController alloc] init] autorelease];
    //添加一个自定义的图标和文字
    two.tabBarItem.title = @"two";
    two.tabBarItem.image = [UIImage imageNamed:@"success.png"];
    [tabBarController addChildViewController:two];
    
    
    
    self.window.rootViewController = tabBarController;
    
    [self.window makeKeyAndVisible];
    return YES;
}

以上代码中，我在第一个Controll View 中添加了一个系统自带的下载图标，，在第二个Controller View中添加了一个自定义的图标（先将图标导入到项目中）和文字。

运行效果如下：

以上的所有代码我都是在AppDelegate.m文件中得

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions{ }函数中实现的，，，这仅仅只是为了操作方便才这样写的，，大多数情况下是写在该tab Bar Controller 的实现文件中的，如这里是在的MyTabController.m文件中的- (id)init{ } 函数中实现的。