点击项目时，TabBar 上的 setBackgroundImage 不起作用答案

【问题标题】：setBackgroundImage on TabBar does not work when tapping items点击项目时，TabBar 上的 setBackgroundImage 不起作用
【发布时间】：2012-11-01 12:19:38
【问题描述】：

我可以设置一次背景，但之后就再也不会改变了。我在stackoverflow上看过所有的例子。代码示例看起来总是一样的。我已经设置了代表。图像一切正常。我已将它们一个接一个地设置为默认图像，并且将显示。但是在应用程序完成启动后，后台不再发生任何事情。

这是我的代码：

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{
    [self customizeInterface];

    // Override point for customization after application launch.
    self.tabController = (UITabBarController *)self.window.rootViewController;
    self.tabController.delegate = self;
...
}

- (void)tabBarController:(UITabBarController *)tabBarController didSelectViewController:(UIViewController *)viewController
{
    int tabitem = self.tabController.selectedIndex;
    NSLog(@"tabitem: %i", tabitem);
    [self switchTabBarImage:tabitem];
    //[[tabController objectAtIndex:tabitem] popToRootViewControllerAnimated:YES];
}

- (void)switchTabBarImage:(int)selectedIndex
{
    NSLog(@"selected: %i", selectedIndex);
    if (selectedIndex == 0) {
        NSLog(@"0");
        UIImage *tabBarBackground = [UIImage imageNamed:@"tabbar-1.png"];
        [[UITabBar appearance] setBackgroundImage:tabBarBackground];
    }
    if (selectedIndex == 1) {
        NSLog(@"1");
        UIImage *tabBarBackground = [UIImage imageNamed:@"tabbar-2.png"];
        [[UITabBar appearance] setBackgroundImage:tabBarBackground];
    }
    if (selectedIndex == 2) {
        NSLog(@"2");
        UIImage *tabBarBackground = [UIImage imageNamed:@"tabbar-3.png"];
        [[UITabBar appearance] setBackgroundImage:tabBarBackground];
    }
    if (selectedIndex == 3) {
        NSLog(@"3");
        UIImage *tabBarBackground = [UIImage imageNamed:@"tabbar-4.png"];
        [[UITabBar appearance] setBackgroundImage:tabBarBackground];
    }
}

- (void)customizeInterface
{

    UIImage *tabBarBackground = [UIImage imageNamed:@"tabbar-1.png"];
    [[UITabBar appearance] setBackgroundImage:tabBarBackground];

    UIImage *selectionIndicator = [UIImage imageNamed:@"tabbar-icon-clean.png"];
    [[UITabBar appearance] setSelectionIndicatorImage:selectionIndicator];

}

调试器显示：

2012-11-13 02:42:06.147 soundapp[9060:c07] tabitem: 1
2012-11-13 02:42:06.148 soundapp[9060:c07] selected: 1
2012-11-13 02:42:06.148 soundapp[9060:c07] 1
2012-11-13 02:42:07.739 soundapp[9060:c07] tabitem: 2
2012-11-13 02:42:07.739 soundapp[9060:c07] selected: 2
2012-11-13 02:42:07.740 soundapp[9060:c07] 2

我搜索了好几个小时，但无法弄清楚为什么它只工作一次。有人看到我的代码有错误吗？

【问题讨论】：

标签： objective-c ios uitabbarcontroller uitabbar setbackground

【解决方案1】：

又过了一个小时，我在网络上的其他地方找到了解决方案 (http://felipecypriano.com/2012/02/27/how-to-customize-uitabbar-on-ios-5/)

- (void)tabBarController:(UITabBarController *)tabBarController didSelectViewController:(UIViewController *)viewController
{
    int tabitem = self.tabController.selectedIndex;
    NSLog(@"tabitem: %i", tabitem);
    [self switchTabBarImage:tabitem];
    //[[tabController objectAtIndex:tabitem] popToRootViewControllerAnimated:YES];
}

- (void)switchTabBarImage:(int)selectedIndex
{

    switch (selectedIndex) {
        case 0:
            [[[self tabController] tabBar] setBackgroundImage:[UIImage imageNamed:@"tabbar-1.png"]];
            break;
        case 1:
            [[[self tabController] tabBar] setBackgroundImage:[UIImage imageNamed:@"tabbar-2.png"]];
            break;
        case 2:
            [[[self tabController] tabBar] setBackgroundImage:[UIImage imageNamed:@"tabbar-3.png"]];
            break;
        case 3:
            [[[self tabController] tabBar] setBackgroundImage:[UIImage imageNamed:@"tabbar-4.png"]];
            break;
    }
}

- (void)customizeInterface
{

    UIImage *tabBarBackground = [UIImage imageNamed:@"tabbar-1.png"];
    [[UITabBar appearance] setBackgroundImage:tabBarBackground];

    UIImage *selectionIndicator = [UIImage imageNamed:@"tabbar-icon-clean.png"];
    [[UITabBar appearance] setSelectionIndicatorImage:selectionIndicator];

}

我真的不明白为什么有两种不同的方式来改变背景。令人困惑的是，这两条不同的代码行只在不同的地方工作。我不明白。但现在可以了。

【讨论】：