// 去掉黑线
    UITabBar *tabBar = [UITabBar appearance];
    [tabBar setBackgroundColor:[UIColor whiteColor]];
    [tabBar setBackgroundImage:[UIImage new]];
    [tabBar setShadowImage:[UIImage new]];
   
    if (@available(iOS 13.0, *)){
        UITabBarAppearance* tabBarAppearance = [[UITabBarAppearance alloc] init];
        tabBarAppearance.shadowColor = [UIColor clearColor];
        [tabBar setStandardAppearance:tabBarAppearance];
    }