如何添加按钮到UINavigationController

Question

我有下面的代码，添加一个导航控制器到模态视图。导航栏和视图全部显示正常，但右侧按钮不显示。我究竟做错了什么？

UpgradesViewController* upgradesViewController = [[UpgradesViewController alloc] initWithNibName:@"UpgradesView" bundle:nil]; 
    upgradesViewController.title = @"Upgrades"; 

    UINavigationController *navController = [[UINavigationController alloc] initWithRootViewController:upgradesViewController]; 
    navController.modalTransitionStyle = UIModalTransitionStyleCoverVertical; 
    navController.navigationBar.barStyle = UIBarStyleBlack; 
    UIBarButtonItem* doneButton = [[UIBarButtonItem alloc] initWithTitle:@"Show" style:UIBarButtonItemStylePlain target: self action:nil]; 
    navController.navigationItem.rightBarButtonItem = doneButton; 
    [self presentModalViewController:navController animated:YES]; 

    [navController release]; 
    [upgradesViewController release]; 

Answer 1

将doneButton添加到upgradedesViewController的navigationItem，而不是navController。导航控制器显示顶部控制器的导航项目，而不是它本身。