修改TabBar的字体大小及选中后的颜色

问题：TabBarItem下的字体太小，默认选中后的颜色不好看

解决：`

class HTabBarController : UITabBarController,UITabBarControllerDelegate {

override func viewDidLoad() {
    super.viewDidLoad();

    var dict = [NSFontAttributeName:UIFont.systemFontOfSize(12)];
    UITabBarItem.appearance().setTitleTextAttributes(dict, forState: UIControlState.Normal);
    UITabBar.appearance().tintColor = UIColor.orangeColor(); 
}   

}
`