iOS10 去掉导航栏分割线

 if ([self.navigationController.navigationBar respondsToSelector:@selector( setBackgroundImage:forBarMetrics:)])    {        NSArray *list=self.navigationController.navigationBar.subviews;        for (id obj in list)        {            if ([UIDevice currentDevice].systemVersion.floatValue >= 10.0)            {//10.0的系统字段不一样                UIView *view = (UIView*)obj;                for (id obj2 in view.subviews) {                    if ([obj2 isKindOfClass:[UIImageView class]])                    {                        UIImageView *image =  (UIImageView*)obj2;                        image.hidden = YES;                    }                  }            }        }    }