原来我们通常这样设置导航栏、tablebar颜色

    NSMutableDictionary *attrs = [NSMutableDictionary dictionary];
    attrs[NSFontAttributeName] = [UIFont systemFontOfSize:12];
    attrs[NSForegroundColorAttributeName] = [UIColor grayColor];
    
    NSMutableDictionary *selAttrs = [NSMutableDictionary dictionary];
    selAttrs[NSFontAttributeName] = attrs[NSFontAttributeName];
    selAttrs[NSForegroundColorAttributeName] = [UIColor lightGrayColor];
   
    UITabBarItem *item = [UITabBarItem appearance];
    
    [item setTitleTextAttributes:attrs forState:UIControlStateNormal];
    [item setTitleTextAttributes:selAttrs forState: UIControlStateDisabled];

但是发现

[item setTitleTextAttributes:sforState:UIControlStateDisabled]；

毫无作用，就跟不存在一样，而

[item setTitleTextAttributes: forState:UIControlStateNormal];

却是好用的··但是永远失去了不可用状态的颜色效果
最后经过研究，发现解决方法不再是设置

[item appearance];

而是设置

[UITabBar appearance];
[UINavigationBar appearance];

的TintColor，应该是新版本更改了api。