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];
原文:http://www.cnblogs.com/wuyuxin/p/7045589.html