切换标签栏时检测选定的标签栏答案

【问题标题】：Detect selected tabbar when switching tab bar切换标签栏时检测选定的标签栏
【发布时间】：2013-01-16 09:45:05
【问题描述】：

我有三个标签栏应用程序，我的标签是 TAB1、TAB2、TAB3 我在 TAB1 视图控制器中编写了以下代码来检测用户按下了哪个标签

- (void)tabBar:(UITabBar *)tabBar didSelectItem:(UITabBarItem *)item 
{ 
    NSLog(@"tab selected: %@", item.title); 
}

但是这个委托永远不会被调用

我已经在 appdelegate.m 中设置了类似的选项卡

- (void)setupTabBar 
{
    self.myWorkListViewController = [[MyWorkListViewController alloc] initWithNibName:@"MyWorkListViewController"
                                                                               bundle:nil];
    self.askHRViewController = [[AskHRViewController alloc] initWithNibName:@"AskHRViewController"
                                                                     bundle:nil];

    self.moreViewController = [[MoreViewController alloc] initWithNibName:@"MoreViewController"
                                                                           bundle:nil];

    self.bookLeaveViewController = [[BookLeaveViewController alloc] initWithNibName:@"BookLeaveViewController"
                                                                             bundle:nil];
    self.helpViewController = [[HelpViewController alloc] initWithNibName:@"HelpViewController"
                                                                   bundle:nil];

    // Create navigation controllers
    workListNavigationController = [[UINavigationController alloc] initWithRootViewController:self.myWorkListViewController];

    askHRNavigationController = [[UINavigationController alloc] initWithRootViewController:self.askHRViewController];

    bookLeaveViewController = [[UINavigationController alloc] initWithRootViewController:self.bookLeaveViewController];

    moreNavigationController = [[UINavigationController alloc] initWithRootViewController:self.moreViewController];

    helpNavigationController = [[UINavigationController alloc] initWithRootViewController:self.helpViewController];

    [self setTabBarImagesAndText];

    // Setup tab bar controller
    self.tabBarController = [[UITabBarController alloc] init];
    [self.tabBarController setViewControllers:[NSArray arrayWithObjects:workListNavigationController, askHRNavigationController, bookLeaveViewController, helpNavigationController,moreNavigationController, nil]];
    //Set TabBar background
    [self.tabBarController.tabBar insertSubview:[[UIImageView alloc] initWithImage:[UIImage imageNamed:@"TabBar_iOS4_Background"]] atIndex:0];
    [self.tabBarController setSelectedIndex:0];

}

【问题讨论】：

标签： iphone ios objective-c

【解决方案1】：

您可以像这样检测选定的 Tabbar 项：- 作为你的代码，你只需要添加这一行

// Setup tab bar controller
    self.tabBarController = [[UITabBarController alloc] init];
    self.tabBarController.delegate=self;
    [self.tabBarController setViewControllers:[NSArray arrayWithObjects:workListNavigationController, askHRNavigationController, bookLeaveViewController, helpNavigationController,moreNavigationController, nil]];
    //Set TabBar background
    [self.tabBarController.tabBar insertSubview:[[UIImageView alloc] initWithImage:[UIImage imageNamed:@"TabBar_iOS4_Background"]] atIndex:0];
    [self.tabBarController setSelectedIndex:0];

在.h文件中定义类似

@interface yourViewcontroller : UIViewController<UITabBarControllerDelegate>
{
   //declare your Tabbar controller with @proparty 
}

在.m文件中

 //@synthesize here your Tabbar controller

- (void)viewDidLoad
{
  self.yourTabbarControler.delegate=self;
    [super viewDidLoad];


}

现在把这个 UITabbarController 的委托放上去

- (void)tabBarController:(UITabBarController *)tabBarController 
 didSelectViewController:(UIViewController *)viewController
{
    NSLog(@"controller class: %@", NSStringFromClass([viewController class]));
    NSLog(@"controller title: %@", viewController.title);

    if (viewController == tabBarController.moreNavigationController)
    {
        tabBarController.moreNavigationController.delegate = self;
    }
}

【讨论】：

这个委托方法也没有在 TAB1viewcontroller 中被调用:(
谢谢 :) :) 但我很惊讶我必须在每个控制器中设置委托。我们不能一次做这个设置吗？
看到这个didSelectViewController 它是UITabbarController 的委托方法，所以每当您需要使用时，您必须声明特定 UItabbarController 的委托，这就是原因

【解决方案2】：

您必须使用代码（在 ViewDidLoad 等中）或在界面构建器中“连接”委托。
看看这个解释如何连接 textView 委托的答案（几乎相同）：https://stackoverflow.com/a/1785366/764575

【讨论】：