Question

TabBar不应启用任何标签，直到用户点击任何一个标签页，下面是我写入显示标签栏的代码，但默认情况下它显示的是第一个标签。

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
    // Override point for customization after application launch.
    self.window.backgroundColor = [UIColor whiteColor];
    [self.window makeKeyAndVisible];

    PeopleViewController *peopleViewController = [[PeopleViewController alloc] init];
    UINavigationController *nav1 = [[UINavigationController alloc] initWithRootViewController:peopleViewController];
    [peopleViewController setTitle:@"People"];

    EventsViewController *eventsViewController = [[EventsViewController alloc] init];
    UINavigationController *nav2 = [[UINavigationController alloc]initWithRootViewController:eventsViewController];
    [eventsViewController setTitle:@"Events"];

    ActiveViewController *activeViewController = [[ActiveViewController alloc] init];
    UINavigationController *nav3 = [[UINavigationController alloc]initWithRootViewController:activeViewController];
    [activeViewController setTitle:@"Active"];

    MoreViewController *moreViewController = [[MoreViewController alloc] init];
    UINavigationController *nav4 = [[UINavigationController alloc] initWithRootViewController:moreViewController];
    [moreViewController setTitle:@"More"];

    NSArray *arrViewControllers = [[NSArray alloc] initWithObjects:nav1,nav2,nav3,nav4, nil];

    [tabBarController setViewControllers:arrViewControllers];
    [self.window addSubview:tabBarController.view];
    return YES;
}

Answer 1

为标签栏创建IBOutlet（例如theTabBar）并使用以下代码：

[theTabBar setSelectedItem:nil];

Answer 2

这是UITabBarController的默认行为，默认选择第一个标签。您可以选择在第一个实例中选择其他选项卡，但不能将选定的默认值更改为null。

[tabBarController setSelectedIndex:0];

默认选择索引为0，这是第一个选项卡，您可以根据需要将其更改为1,2,3。

UITabBar功能

2 个答案: