iOS 15.0 Tab Bars笔记

在iOS 15.0中，Tab Bar的背景也有同Navigation Bars同样的问题，常见的问题就是背景变成透明了，或者内嵌的ScrollView滚动到最底端的时候，Tab Bar的背景变成透明的了。

所以我们同样需要添加scrollEdgeAppearance的值，建议和standardAppearance的值保持一致。例如：

    UITabBarAppearance *tabBarAppearance = [[UITabBarAppearance alloc] init];
    [tabBarAppearance configureWithDefaultBackground];
    [[UITabBar appearance] setStandardAppearance:tabBarAppearance];
    if (@available(iOS 15.0, *)) {
        [[UITabBar appearance] setScrollEdgeAppearance:[UITabBar appearance].standardAppearance];
    }

一般情况下，我们使用系统默认的Tab Bars就可以了，如果需要配置外观，可以通过下面的外观属性进行精确的配置。

• UIBarAppearance
• UITabBarItemAppearance
• UITabBarItemStateAppearance

例如：

    UITabBarAppearance *tabBarAppearance = [[UITabBarAppearance alloc] init];
    [tabBarAppearance configureWithDefaultBackground];
    UITabBarItemAppearance *stackedLayoutAppearance = [[UITabBarItemAppearance alloc] initWithStyle:UITabBarItemAppearanceStyleStacked];
    stackedLayoutAppearance.normal.iconColor = [UIColor systemPurpleColor];
    stackedLayoutAppearance.selected.iconColor = [UIColor systemBrownColor];
    tabBarAppearance.stackedLayoutAppearance = stackedLayoutAppearance;
    [[UITabBar appearance] setStandardAppearance:tabBarAppearance];
    if (@available(iOS 15.0, *)) {
        [[UITabBar appearance] setScrollEdgeAppearance:[UITabBar appearance].standardAppearance];
    }

如果需要特殊的功能，例如咸鱼风格的Tab Bar，那么一般是自定义Tab Bar来覆盖系统的。

目前我用到的Tab Bar的第三方库，AxcAE_TabBar 还不错，应该能满足各种需求。