UITabBar功能

Question

在用户单击任何一个选项卡之前，TabBar不应该启用任何选项卡，下面是我编写代码来显示选项卡栏，但问题是它默认显示的是第一个选项卡。

- (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

为选项卡栏创建一个IBOutlet (例如theTabBar)，并使用以下代码：

[theTabBar setSelectedItem:nil];

Answer 2

这是UITabBarController的默认行为，默认情况下第一个选项卡处于选中状态。您可以选择在第一个实例中选择其他选项卡，但不能将默认选择项更改为空。

[tabBarController setSelectedIndex:0];

默认选择的指标为0，这是第一个页签，您可以根据需要修改为1,2,3。