有没有办法让按钮在整个 UINavigationController 堆栈中保持不变？

Question

我知道如何为我推入导航控制器堆栈的每个控制器添加一个按钮。 但是我需要始终在导航栏的右上角有一个设置按钮，无论哪个控制器被按下或弹出。该按钮应以模态方式显示设置视图控制器。

对我来说，让每个控制器的 viewDidLoad 都包含按钮代码以及设置控制器标题似乎是一种 hack。

似乎我应该能够从导航控制器本身插入此按钮，指向导航控制器中的选择器。然后，此方法将通过此时恰好在堆栈中处于活动状态的任何控制器以模态方式呈现 settingsController。

关于如何实现这一点的任何想法？

Answer 1

好的，这就是我所做的：

1 - 子类 UINavigationController 并包含我的设置控制器的标题

2 - 覆盖 -pushViewController:aniamted:

- (void)pushViewController:(UIViewController *)viewController animated:(BOOL)animated
{
    [super pushViewController:viewController animated:animated];
    UIBarButtonItem *settingsButton = [[UIBarButtonItem alloc]initWithTitle:@"Settings" 
                                                                      style:UIBarButtonItemStylePlain 
                                                                     target:self
                                                                     action:@selector(shouldPresentSettingsView)];
    [viewController.navigationItem setRightBarButtonItem: settingsButton];
    [settingsButton release];
}

3 - 添加两个方法：

- (void)shouldPresentSettingsView
{
    SetupViewController *settingsView = [[SetupViewController alloc] init];
    UINavigationController *tempController = [[UINavigationController alloc]initWithRootViewController:settingsView];
    UIBarButtonItem *cancelButton = [[UIBarButtonItem alloc] initWithTitle:@"Back" 
                                                                     style:UIBarButtonItemStylePlain 
                                                                    target:self 
                                                                    action:@selector(shouldDismissSettingsView)];
    settingsView.navigationItem.leftBarButtonItem = cancelButton;
    [self.visibleViewController presentModalViewController:tempController animated:YES];

    [cancelButton release];
    [settingsView release];
    [tempController release];
}

- (void)shouldDismissSettingsView
{
    [self dismissModalViewControllerAnimated:YES];
}

Answer 2

将导航控制器的委托设置为全局对象，例如应用委托。在该对象中，初始化 UIBarButtonItem 并保存到实例变量：

- (void)setupSettingsButton
{
    settingsBarButton = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemCompose 
                                                                      target:self 
                                                                      action:@selector(openSettings)];
}

然后在推送前配置每个视图控制器的navigationItem：

- (void)navigationController:(UINavigationController *)aNavigationController willShowViewController:(UIViewController *)viewController animated:(BOOL)animated
{
    viewController.navigationItem.rightBarButtonItem = settingsBarButton;
}

并处理按钮操作...

- (void)openSettings
{
    [navigationController presentViewController:settingsVC animated:YES completion:NULL];
}