ios - vc中present了一个带nav的vc，但是弹出的vc不能设置其nav的titile和baritem？

Question

如题，present的代码是这样的

UINavigationController* cityListNav = [[UINavigationController alloc]initWithRootViewController:cityList];
   /*
    cityListNav.navigationItem.leftBarButtonItem = [[UIBarButtonItem alloc]initWithImage:[UIImage imageNamed:@"ic_me_back"] style:UIBarButtonItemStylePlain target:self action:@selector(closeCityList)];
    */
    cityListNav.navigationItem.leftBarButtonItem = [[UIBarButtonItem alloc] initWithTitle:@"返回"style:UIBarButtonItemStyleDone target:self action:@selector(closeCityList)];

    cityListNav.navigationBar.backgroundColor = [UIColor whiteColor];
    cityListNav.title = @"城市选择";

     [self presentViewController:cityListNav animated:YES completion:nil];

无论在present的vc内外设置nav都没有反应，无论什么方式添加leftbaritem也都没有反应好，只有background可以。。。。
一开始我以为是特例，在别的控制器present了一个别的带nav的vc也是一样的结果。。。

是我哪里做错了嘛，有大神遇到这样的问题没？ 谢谢

Answer 1

The answer above should be clearer. You should not set the BarButton and title on the UINavigationController, but on the UIViewController it manages.

This is reflected in your code: you should set it on the cityList UIViewController, not the cityListNav UINavigationController.

Answer 2

is cityList.title not cityListNav.title