如何在使用UIPageViewController时将UIBarButtonItem添加到NavigationBar [英] How to add UIBarButtonItem to NavigationBar while using UIPageViewController

问题描述

请原谅，关于如何以编程方式将UIBarButtonItem添加到NavigationBar的问题已经很多，但我似乎无法获得适合我情况的任何解决方案.

Please forgive me, there are already a ton of questions on how to add a UIBarButtonItem to a NavigationBar programmatically but I just can't seem to get any of the solutions to work in my situation.

这是我用来学习UIPageViewController的简单测试应用程序的布局.

Here is the layout of a simple test app I have been working with to learn the UIPageViewController.

我让页面视图控制器与三个独特的viewController一起很好地工作.我现在想为每个视图控制器设置唯一的rightBarButtonItems.只需执行此操作，就可以轻松地在DetailViewController中设置通用的barButtonItem.

I have the page view controller working nicely with three unique viewControllers. I would now like to set unique rightBarButtonItems for each of the view controllers. I can easily set a common barButtonItem in the DetailViewController by simply doing this.

UIBarButtonItem *newButton = [[UIBarButtonItem alloc] initWithTitle:@"Whatever" 
                              style:UIBarButtonItemStylePlain 
                              target:self 
                              action:@selector(doSomething)];    

self.navigationItem.rightBarButtonItem = newButton;

鉴于我在pageViewController的三个页面中的每个页面都需要一个唯一的按钮，因此无法在detailViewController中设置按钮.我已经在三个控制器的viewDidAppear中尝试了上面的代码，但是按钮不会出现.我也尝试过以相同的方式创建按钮，然后像这样设置它，但是没有运气.

Given that I need a unique button for each of the three pages in the pageViewController I am not able to set the button in the detailViewController. I have tried the code above in viewDidAppear of the three controllers but the buttons will not appear. I have also tried creating the button in the same way and then setting it like this with no luck.

DetailViewController *vc = [[DetailViewController alloc] init];
vc.navigationItem.rightBarButtonItem = newButton;

我知道我已经接近这里了，我只是不确定如何指定我需要向运行我的contentViewController嵌入的detailViewController的NavigationController的NavigationBar中添加一个按钮.任何帮助都特别重要片段.

I know I'm close here, I'm just not sure how to specify I need to add a button to the NavigationBar of the NavigationController that is running the detailViewController that my contentViewControllers are embedded in. Any help would be great ESPECIALLY SNIPPETS.

作为旁注，我尝试了其他一些有问题的方法.

As a side note I have tried a few other methods that have come up problematic.

• 在viewDidLoad中而不是viewDidAppear中设置按钮
  • 这将不起作用，因为您每次从一页滑至下一页时都不会调用viewDidLoad方法. viewDidAppear方法是，所以我试图在那里设置按钮.可能每次都调用viewWillAppear，但是我没有检查.
  • Setting the button in viewDidLoad rather than viewDidAppear
    • This will not work because the viewDidLoad method is not called everytime you swipe from one page to the next. The viewDidAppear method is however so I am trying to set the button there. It is possible viewWillAppear is called everytime but I haven't checked.
    • 如果用户快速翻阅页面，则按钮将无法更改或无法显示，这是有问题的.

    解决方案

    SOLUTION

    事实证明我已经关闭了……而不是在UIPageViewController方法中创建按钮，我只需要在我的三个视图控制器中的每一个中创建一个navigationItem属性.当在委托方法中实例化控制器时，我只需将navigationItem属性设置为与detailViewController相等.这样，在我的viewDidApper方法中，我可以创建按钮.然后在viewWillDisappear处将按钮设置为nil.您也可以只在DetailViewController的viewdidLoad处创建按钮，并在各个viewController的viewDidAppear中更改文本和操作.这是一个示例.

    It turns out I was close… Rather than creating the button in the UIPageViewController methods I simply needed to create a navigationItem property in each of my three view controllers. When the controllers are instantiated in the delegate methods I simply set the navigationItem property equal to that of the detailViewController. That way in my viewDidApper methods I could create the button. Then at viewWillDisappear I set the button to nil. You can also just create the button at viewdidLoad of the DetailViewController and change the text and action in viewDidAppear of the individual viewControllers. Here is a sample.

    在委托方法中

    - (UIViewController *)pageViewController:(UIPageViewController *)pageViewController viewControllerBeforeViewController:(UIViewController *)viewController
    
    - (UIViewController *)pageViewController:(UIPageViewController *)pageViewController viewControllerAfterViewController:(UIViewController *)viewController
    

    我根据viewController的索引调用一个辅助方法.辅助方法在调用时实例化视图控制器.实例化后，我将设置一些属性，包括navigationItem属性.

    I call a helper method based on the index of the viewController. The helper method instantiates the view controllers when it is called. Once instantiated I set some properties including the navigationItem property.

    -(FirstController *)controllerAtIndex:(NSUInteger)index
    {
    
        FirstController *fvc = [self.storyboard instantiateViewControllerWithIdentifier:@"FirstPageController"];
        fvc.imageFile = self.pageImages[index];
        fvc.titleText = self.pageTitles[index];
        fvc.pageIndex = index;
        fvc.navItem = self.navigationItem;
        return fvc;
    
    }
    

    然后在viewController的viewDidAppear中，我只是这样做

    Then in the viewDidAppear of the viewController I just do this

    -(void)viewDidAppear:(BOOL)animated
    {
    
        UIBarButtonItem *newButton = [[UIBarButtonItem alloc]
                                   initWithTitle:@"Whatever" style:UIBarButtonItemStylePlain target:self action:@selector(doSomething)];
        navItem.rightBarButtonItem = newButton;
    
    }
    

    推荐答案

    如果每次更改查看的页面时都需要更改按钮，则必须使用您尝试过的一种委托方法来完成.但是，我建议您不要更改新按钮并将其设置为导航项，而只需更改标题即可.

    If you need the button to change each time you change the page you look at, it must be done in one of the delegate methods that you have tried. I suggest however, that instead of creating a new button and setting it to the navigation item, you simply change the title.

    您可以在界面生成器中创建按钮，并将其链接到DetailViewController中的属性，然后每次进入新页面时，使用按钮上的UIControlStateNormal调用setTitle:forState.

    You can create the button in interface builder and link it to a property in your DetailViewController and then call setTitle:forState with UIControlStateNormal on the button every time you go to a new page.

    如果您需要按钮为每个页面做一些不同的事情，我建议您在按钮操作方法中检查当前页面，而不是每次都声明一个新页面.

    If you need the button to do something different for each page, I would recommend checking the current page in the buttons action method rather than declaring a new one each time.

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