如何识别标签栏项目？

Posted 2023-03-03

【中文标题】如何识别标签栏项目？

【英文标题】：How to Identify tab bar items?

【发布时间】：2009-08-15 12:53:31

【问题描述】：

我想知道如何识别标签栏中的项目？

我有一个包含 NAvigationController 的 tabBarController，如下所示：

NSMutableArray *localViewControllersArray = [[NSMutableArray alloc] initWithCapacity:6];

每个 navigationController 都在这个数组中。

---

我使用方法管理每个标签栏项中的操作：

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

而我在这个方法中，即：

if (viewController == [self.tabBarController.viewControllers objectAtIndex:0])

像这样我可以识别我点击的标签栏项目。

但问题是您可以在 iphone 屏幕中编辑 Tabbar（因为数组中有 6 个 viewControllers 初始化了 tabbar）然后，我使用的方式不正确，因为我可以更改位置使用此编辑工具时标签栏中的视图控制器。

谢谢

【参考方案1】：

您可以使用UITabBarItem 的标签属性为每个UITabBarItem 赋予一个唯一的数字标识符，然后进行比较。

例子：

#define FirstViewController 1
#define SecondViewController 2
switch ([[viewController tabBarItem] tag]) 
  case FirstViewController:
    //the user selected your first view controller, no matter where it is on the tabbar
    break;
  case SecondViewController:
    break;
  ... etc

您可以记住指向每个 navigationControllers 的指针，并将它们与 viewController 参数进行比较。

例子：

//during your initial setup of the tabBarController:
UIViewController * firstViewController = //The view controller in the first tab
UIViewController * secondViewController = //The view controller in the second tab

...

if (viewController == firstViewController) 
  ...
 else if (viewController == secondViewController) 
  ...

您可以禁止对 UITabBarController 进行编辑（将空数组或 nil 传递给控制器​​的 customizableViewControllers 属性）。

例子：

[myTabBarController setCustomizableViewControllers:nil];

【讨论】：

1) 如果我给每个 UITabBarItem 一个 UITabBarItem 的标签，我不会将此 tabbaritem 与 viewcontroller 关联，对吗？我的意思是，如果我编辑 tabbar，那么我可以找到 tabbaritem，但不是视图控制器。 2）如何做到这一点？ 3）这将是我的最后一个选择，因为我想解决问题，并允许编辑标签栏。我比较的方式是这样的： if (viewController == [self.tabBarController.viewControllers objectAtIndex:0]) 我应该这样改变吗？谢谢

【参考方案2】：

但是，我正在像这样创建 ViewController：（然后我不能创建#define，或者输入不同的名称）

(UINavigationController *)createNavigationControllerWrappingViewControllerForDataSourceOfClass:(Class)datasourceClass

id<VideosDataSource,UITableViewDataSource> dataSource = [[datasourceClass alloc] init];

// create the VideosTableViewController and set the datasource
VideosTableViewController *theViewController;   
theViewController = [[VideosTableViewController alloc] initWithDataSource:dataSource];

// create the navigation controller with the view controller
UINavigationController *theNavigationController;
theNavigationController = [[UINavigationController alloc] initWithRootViewController:theViewController];

// before we return we can release the dataSource (it is now managed by the ElementsTableViewController instance
[dataSource release];

// and we can release the viewController because it is managed by the navigation controller
[theViewController release];

return theNavigationController;

(void)setupPortraitUserInterface

// a local navigation variable
// this is reused several times
UINavigationController *localNavigationController;

// Create a tabbar controller and an array to contain the view controllers
tabBarController = [[UITabBarController alloc] init];

// define a custom frame size for the entire tab bar controller that will be in the
// bottom half of the screen.
CGRect tabBarFrame;
tabBarFrame = CGRectMake(0, 0, 320, 460);
tabBarController.view.frame = tabBarFrame;

NSMutableArray *localViewControllersArray = [[NSMutableArray alloc] initWithCapacity:6];

// setup the 6 view controllers for the different data representations

// create the view controller and datasource for the VideosSortedBySuggestionsDataSource
// wrap it in a UINavigationController, and add that navigationController to the 
// viewControllersArray array

localNavigationController = [self createNavigationControllerWrappingViewControllerForDataSourceOfClass:[VideosSortedBySuggestionsDataSource class]];
[localViewControllersArray addObject:localNavigationController];

// the localNavigationController data is now retained by the application delegate
// so we can release the local variable
[localNavigationController release];


// repeat the process for the VideosSortedBySuggSearchDataSource
localNavigationController = [self createNavigationControllerWrappingViewControllerForDataSourceOfClass:[VideosSortedBySuggSearchDataSource class]];
[localViewControllersArray addObject:localNavigationController];

// the localNavigationController data is now retained by the application delegate
// so we can release the local variable
[localNavigationController release];            


// repeat the process for the VideosSortedByMostViewedDataSource
localNavigationController = [self createNavigationControllerWrappingViewControllerForDataSourceOfClass:[VideosSortedByMostViewedDataSource class]];
[localViewControllersArray addObject:localNavigationController];

// the localNavigationController data is now retained by the application delegate
// so we can release the local variable
[localNavigationController release];


// repeat the process for the VideosSortedByTopRatedDataSource
localNavigationController = [self createNavigationControllerWrappingViewControllerForDataSourceOfClass:[VideosSortedByTopRatedDataSource class]];
[localViewControllersArray addObject:localNavigationController];

// the localNavigationController data is now retained by the application delegate
// so we can release the local variable
[localNavigationController release];


// repeat the process for the VideosSortedBySearchDataSource
localNavigationController = [self createNavigationControllerWrappingViewControllerForDataSourceOfClass:[VideosSortedBySearchDataSource class]];
[localViewControllersArray addObject:localNavigationController];

// the localNavigationController data is now retained by the application delegate
// so we can release the local variable
[localNavigationController release];


// repeat the process for the VideosSortedBySearchDataSource
localNavigationController = [self createNavigationControllerWrappingViewControllerForDataSourceOfClass:[VideosSortedBySearchDataSource class]];
[localViewControllersArray addObject:localNavigationController];

// the localNavigationController data is now retained by the application delegate
// so we can release the local variable
[localNavigationController release];


// set the tab bar controller view controller array to the localViewControllersArray
tabBarController.viewControllers = localViewControllersArray;
// the localViewControllersArray data is now retained by the tabBarController
// so we can release this version
[localViewControllersArray release];
// set the window subview as the tab bar controller
[self.view addSubview:tabBarController.view];

【参考方案3】：

为此，我从 Elements 演示开始。在那个演示中，每个数据源都有自己的覆盖名称。然后，任何时候我需要为特定选项卡做某事（因为它的数据源与其他选项卡不同），在我的主导航控制器中，我会这样做：

if (datasource.name == @"Some name") 
    // something

【讨论】：

但是如果你在我解释过的同一个班级（每个 ViewController 都在哪里声明）你不能调用“datasource.name”因为不存在这个。你怎么能在同一个班级里打电话来进行比较？谢谢

VideosTableViewController * tabbedViewController = (VideosTableViewController *)[[localViewControllersArray objectAtIndex:[WHATEVER]] topViewController]; if (tabbedViewController.dataSource.name == @"Something") // 做点什么