UITabBarController中的每个子控制器展示内容，如果从内容页面跳转到详情页面的时候需要隐藏底部，我们可以设置
hidesBottomBarWhenPushed属性:
FlyElephantController *controller=[[UIStoryboard storyboardWithName:@"CourseCenter" bundle:nil] instantiateViewControllerWithIdentifier:@"FlyElephantController"];
controller.hidesBottomBarWhenPushed=YES;
[self.navigationController pushViewController:controller animated:YES];
