UITabBarItem's appearance

1.我们知道，用tabBarController创建出来默认的tabBar似这个样子滴。。。

-----------------我是图片分割线--------------------------------

2.通常通过appearance统一设置，可以一劳永逸，不必在每个控制器设置

@implementation TTTabBarController

+(void)initialize{

    //normal状态的文字属性
    NSMutableDictionary *attrDic = [[NSMutableDictionary alloc]init];
    [attrDic setValue:[UIColor grayColor] forKey:NSForegroundColorAttributeName];
    [attrDic setValue:[UIFont systemFontOfSize:] forKey:NSFontAttributeName];

    //select状态的文字属性
    NSMutableDictionary *selectedAttrDic = [[NSMutableDictionary alloc]init];
    [selectedAttrDic setValue:[UIColor darkGrayColor] forKey:NSForegroundColorAttributeName];
    [selectedAttrDic setValue:[UIFont systemFontOfSize:] forKey:NSFontAttributeName];

    //项目中所有tabBarItem都将是这种文字状态
    UITabBarItem *item = [UITabBarItem appearance];
    [item setTitleTextAttributes:attrDic forState:UIControlStateNormal];//normal状态
    [item setTitleTextAttributes:selectedAttrDic forState:UIControlStateSelected];//select状态
}

效果如下：