在继承 UITabBarController 的子类中加入以下代码
oc：
+ (void)initialize
{
//获取当前这个类下面的所有的tabBarItem
UITabBarItem *item;
if (CurrentDeviceVersion < 9.0) {
item = [UITabBarItem appearanceWhenContainedIn:self, nil];
} else {
item = [UITabBarItem appearanceWhenContainedInInstancesOfClasses:@[self]];
}
NSMutableDictionary *attSelected = [NSMutableDictionary dictionary];
attSelected[NSForegroundColorAttributeName] = [UIColor colorWithR:113 G:179 B:217];
[item setTitleTextAttributes:attSelected forState:UIControlStateSelected];
NSMutableDictionary *attNormal = [NSMutableDictionary dictionary];
attNormal[NSForegroundColorAttributeName] = [UIColor darkGrayColor];
attNormal[NSFontAttributeName] = [UIFont systemFontOfSize:14.0];
[item setTitleTextAttributes:attNormal forState:UIControlStateNormal];
}
swift：
vc.tabBarItem.setTitleTextAttributes([NSForegroundColorAttributeName:UIColor.orange], for: .selected)
vc.tabBarItem.setTitleTextAttributes([NSFontAttributeName:UIFont.systemFont(ofSize: 14)], for: .normal)
（vc为继承自UITabBarController的类的childViewController）
纯属个人笔记，如有错误，欢迎指出。
