Question

我有一个由MainWindow.xib创建的标签栏控制器。我有4个视图控制器。现在我想以编程方式添加第5项（因为我不知道在编译时我必须使用哪个类）

这是我的代码：

UIViewController * login = [[LoginUserViewController alloc] initWithNibName:@"LoginUserViewController" bundle:nil];

NSMutableArray * viewControllersArray = [NSMutableArray arrayWithArray:self.tabBarController.viewControllers];
[viewControllersArray addObject:login];
[self.tabBarController setViewControllers:viewControllersArray
                                 animated:YES];

但是我得到了

[LoginUserViewController viewControllers]: unrecognized selector sent to instance 0x95791b0'

当我到达此代码时

UINavigationController *navController = [tabBarController.viewControllers lastObject];
LoginViewController * log = [navController.viewControllers objectAtIndex:0];

我哪里错了？有任何想法吗？

非常感谢

Answer 1

您忘记了最后一个标签是LoginUserViewController，而不是UINavigationController的实例。

将LoginUserViewController添加到标签栏控制器后，标签栏控制器数组中的最后一个视图控制器将是LoginUserViewController，而不是UINavigationController的实例

UINavigationController *navController = [tabBarController.viewControllers lastObject];

因此上面的行将在navController变量中返回LoginUserViewController的对象。

RecordsViewController *recordsViewController = [navController.viewControllers objectAtIndex:0];

因此，由于LoginUserViewController没有viewControllers属性，因此上面的行会导致崩溃。

Answer 2

如果这是您的所有代码，则看起来您不是在实例化导航控制器。看看：

initWithRootViewController:

UINavigatorClass中的

。我会替换：

UINavigationController *navController = [tabBarController.viewControllers lastObject];

使用：

UINavigationController *navController = [[UINavigationController alloc] initWithRootViewController: [tabBarController.viewControllers lastObject]];

编辑：还有一个想法：看起来你在“tabBarController”属性上运气好，因为你可能已将它合成为@synthesize tabBarController=tabBarController;
我强烈建议您使用最新版本的XCode，它会自动为您执行@synthesize。代码中最后一行应该是self.tabBarController

Answer 3

试试这个......

  - (void) setUpTabBar {
FirstViewController *firstViewController = [[FirstViewController alloc]init];
firstViewController.title = @"First View";
firstViewController.tabBarItem = [[UITabBarItem alloc]initWithTabBarSystemItem:UITabBarSystemItemSearch tag:0];
UINavigationController *firstNavController = [[UINavigationController alloc]initWithRootViewController:firstViewController];

SecondViewController *secondViewController = [[SecondViewController alloc]init];
secondViewController.title = @"Second View";
secondViewController.tabBarItem = [[UITabBarItem alloc]initWithTabBarSystemItem:UITabBarSystemItemFavorites tag:1];
UINavigationController *secondNavController = [[UINavigationController alloc]initWithRootViewController:secondViewController];

ThirdViewController *thirdViewController = [[ThirdViewController alloc]init];
thirdViewController.title = @"Third View";
thirdViewController.tabBarItem = [[UITabBarItem alloc]initWithTabBarSystemItem:UITabBarSystemItemRecents tag:2];
UINavigationController *thirdNavController = [[UINavigationController alloc]initWithRootViewController:thirdViewController];

ForthViewController *forthViewController = [[ForthViewController alloc]init];
forthViewController.title = @"Forth View";
forthViewController.tabBarItem = [[UITabBarItem alloc]initWithTabBarSystemItem:UITabBarSystemItemHistory tag:2];
UINavigationController *forthNavController = [[UINavigationController alloc]initWithRootViewController:forthViewController];

tabBarController = [[UITabBarController alloc] initWithNibName:nil bundle:nil];
tabBarController.viewControllers = [[NSArray alloc] initWithObjects:firstNavController, secondNavController, thirdNavController, forthNavController, nil];
tabBarController.delegate = self;             
[self sizeViewToAvailableWindow:[tabBarController view]];

[firstNavController release];
[firstViewController release];

[secondNavController release];
[secondViewController release];

[thirdNavController release];
[thirdViewController release];

[forthNavController release];
[forthViewController release];
}

将新的viewcontroller添加到选项卡控制器

3 个答案: