iOS 5 自定义标签栏图像垂直对齐

问题描述

我的自定义标签栏出现了一些奇怪的行为.图像似乎对齐不正确.这是一个截图(我已经删除了我自己的标签栏背景以突出我的问题):

I'm getting some odd behaviour with my custom tab bar. The images seem to be aligned incorrectly. Here is a screenshot (I have removed my own tab bar background to highlight my problem):

这是我用来为每个状态设置图像的代码:

Here is the code I'm using to set the images for each state:

self.tabBarController = [[[UITabBarController alloc] init] autorelease];
self.tabBarController.viewControllers = [NSArray arrayWithObjects:homeNavController, whatsOnNavController, mapNavController, infoNavController, nil];
self.tabBarController.delegate = self;

// For iOS 5 only - custom tabs
if ([self.tabBarController.tabBar respondsToSelector:@selector(selectedImageTintColor)]) 
{

    // Set the background images
    //[[UITabBar appearance] setBackgroundImage: [UIImage imageNamed:@"nav_bg.png"]];
    [[UITabBar appearance] setSelectionIndicatorImage:[UIImage imageNamed:@"nav_over.png"]];

    [homeNavController.tabBarItem setFinishedSelectedImage:[UIImage imageNamed:@"nav_home_over"] withFinishedUnselectedImage:[UIImage imageNamed:@"nav_home"]];
    [whatsOnNavController.tabBarItem setFinishedSelectedImage:[UIImage imageNamed:@"nav_whats_on_over"] withFinishedUnselectedImage:[UIImage imageNamed:@"nav_whats_on"]];
    [mapNavController.tabBarItem setFinishedSelectedImage:[UIImage imageNamed:@"nav_map_over"] withFinishedUnselectedImage:[UIImage imageNamed:@"nav_map"]];
    [infoNavController.tabBarItem setFinishedSelectedImage:[UIImage imageNamed:@"nav_info_over"] withFinishedUnselectedImage:[UIImage imageNamed:@"nav_info"]];

}

我的所有替换标签图像的大小都正确(非视网膜版本为 49 像素高和 80 像素宽).

All of my replacement tab images are correctly sized (49 pixels high and 80 pixels wide for the non-retina versions).

什么可能导致这种奇怪的行为?

What could be causing this odd behaviour?

这是一个更新的屏幕截图，背景已经到位:

Here is an updated screenshot with the background in place:

推荐答案

事实证明，您应该始终在 tabitem 中包含文本.该空间是由空白文本创建的.

It turns out that you should always have text inside a tabitem. The space was created by blank text.

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