IOS 杂笔－13（appearance的巧妙使用）

NSDictionary * attrs = @{

                             NSFontAttributeName:[UIFont systemFontOfSize:13],
                             NSForegroundColorAttributeName:[UIColor grayColor]

                             };

    NSDictionary * selectAttrs = @{

                                   NSFontAttributeName:[UIFont systemFontOfSize:12],
                                   NSForegroundColorAttributeName:[UIColor darkGrayColor]

                                   };

    UITabBarItem * item = [UITabBarItem appearance];
    [item setTitleTextAttributes:attrs forState:UIControlStateNormal];
    [item setTitleTextAttributes:selectAttrs forState:UIControlStateSelected];