Question

我写的这个应用程序有问题。

我正在我的应用程序窗口中设置UITabBar并在视图文件中设置图标。但是当我运行应用程序时，第一个图标显示出来（因为视图已加载，我猜）并且其他图标在我点击之前不会显示。

我是否需要在self.tabBarItem以外的其他方法中实施viewDidLoad？

先感谢大家！

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {    
    tabBar = [[UITabBarController alloc] init];

    SubscriptionsController *subscriptionsController = [[SubscriptionsController alloc] init];
    FavoritesController  *favoritesController  = [[FavoritesController  alloc] init];
    CategoriesController *categoriesController  = [[CategoriesController alloc] init];
    TagsController   *tagsController    = [[TagsController   alloc] init];
    HelpScreenController *helpScreenController  = [[HelpScreenController alloc] init];

    tabBar.viewControllers = [NSArray arrayWithObjects:
        subscriptionsController, 
        favoritesController, 
        categoriesController, 
        tagsController, 
        helpScreenController, 
        nil
        ];

    [window addSubview:tabBar.view];

    // Override point for customization after application launch.
    [window makeKeyAndVisible];
    return YES;
}

//The View

- (void)viewDidLoad {
    [super viewDidLoad];
    tabIcon = [[UITabBarItem alloc] initWithTitle:@"Abonime" image:[UIImage imageNamed:@"subscr.png"] tag:0];
    self.tabBarItem = tabIcon;
    [tabIcon release];
}

Answer 1

我认为您应该在视图控制器的指定初始化程序中设置tabBarItem属性（从您的代码判断，每个控制器必须为-init）。实际上，标签栏控制器非常智能，可以按需加载视图，也就是说，应该在发送viewDidLoad之前设置tabBarItem属性。

此外，您似乎泄漏了所有视图控制器。要解决此问题，请执行以下操作：

SubscriptionsController *subscriptionsController = [[[SubscriptionsController alloc] init] autorelease];

Answer 2

正确。图标不会显示，因为视图（第一个除了之外，尚未加载）。并且在点击视图之前不会加载，因为直到那时才调用viewDidLoad。

删除单个UIViewControllers viewDidLoad中的代码并执行此操作...

NSArray *controllers = [NSArray arrayWithObjects:
                                                [NSDictionary dictionaryWithObjectsAndKeys:@"SubscriptionsController", @"class", [UIImage imageNamed:@"btn_tax.png"], @"icon", @"Abonime", @"title", nil],
                                                [NSDictionary dictionaryWithObjectsAndKeys:@"FavoritesController", @"class", [UIImage imageNamed:@"btn_tax.png"], @"icon", @"Abonime", @"title", nil],
                                                [NSDictionary dictionaryWithObjectsAndKeys:@"CategoriesController", @"class", [UIImage imageNamed:@"btn_tax.png"], @"icon", @"Abonime", @"title", nil],
                                                [NSDictionary dictionaryWithObjectsAndKeys:@"TagsController", @"class", [UIImage imageNamed:@"btn_tax.png"], @"icon", @"Abonime", @"title", nil],
                                                [NSDictionary dictionaryWithObjectsAndKeys:@"HelpScreenController", @"class", [UIImage imageNamed:@"btn_tax.png"], @"icon", @"Abonime", @"title", nil],
                                                nil];

NSMutableArray *controllerArray = [NSMutableArray array] ;

 for (NSUInteger i = 0; i < [controllers count]; i++)
 {
    id newClass = [[NSClassFromString([[controllers objectAtIndex:i] objectForKey:@"class"]) alloc] init];
    UITabBarItem *tabItem = [[UITabBarItem alloc] init];
    tabItem.image = [[controllers objectAtIndex:i] objectForKey:@"icon"];
    tabItem.title = [[controllers objectAtIndex:i] objectForKey:@"title"];
    tabItem.tag = i;
    [(UIViewController*)newClass setTabBarItem:tabItem];
    [tabItem release];
    [controllerArray addObject:newClass];
    [newClass release];
 }

 tabBar.viewControllers = controllerArray;

UITabBar中的UITabBarItems在我单击项目后显示，而不是在应用程序启动时

2 个答案: