Ios RightBarButtonItem仅显示为不活动

我在尝试将刷新按钮显示为RightBarButtonim时遇到了一个奇怪的问题

简而言之，我已经实现了它，但在运行应用程序时看不到任何东西。但是，当我单击情节提要

调试-->视图调试-->捕获视图层次结构时

。我可以看到一个刷新按钮，似乎不活动和隐藏。我不知道为什么

viewcontrol实际上是通过自定义的pageviewcontroller推入的

- (void)viewDidLoad {
    [super viewDidLoad];

    self.pageController = [[UIPageViewController alloc] initWithTransitionStyle:UIPageViewControllerTransitionStyleScroll navigationOrientation:UIPageViewControllerNavigationOrientationHorizontal options:nil];

    self.pageController.dataSource = self;
    [[self.pageController view] setFrame:[[self view] bounds]];

    TNViewController *initialViewController = [self viewControllerAtIndex:currentIndex];
    UIBarButtonItem *refreshButton = [[UIBarButtonItem alloc]
                                       initWithBarButtonSystemItem:UIBarButtonSystemItemRefresh
                                       target:self action:@selector(refreshClicked:)];
    initialViewController.navigationItem.rightBarButtonItem = refreshButton;
    UINavigationController *navigationController = [[UINavigationController alloc] initWithRootViewController:initialViewController];

    NSArray *viewControllers = [NSArray arrayWithObject:navigationController];

    [self.pageController setViewControllers:viewControllers direction:UIPageViewControllerNavigationDirectionForward animated:NO completion:nil];

    [self addChildViewController:self.pageController];
    [[self view] addSubview:[self.pageController view]];
    [self.pageController didMoveToParentViewController:self];

    for (UIView *subview in self.pageController.view.subviews) {
        if ([subview isKindOfClass:[UIPageControl class]]) {
            UIPageControl *pageControl = (UIPageControl *)subview;
            pageControl.pageIndicatorTintColor = [UIColor blackColor];
            pageControl.currentPageIndicatorTintColor = [utils colorFromHexString:@"#AA3635"];
            pageControl.numberOfPages = _news.count;
            pageControl.backgroundColor = [UIColor whiteColor];
        }
    }
    self.edgesForExtendedLayout = UIRectEdgeTop;
}

---

请问我缺少什么？

因为要将其添加到uiviewcontroller，所以需要创建UINavigationBar、UINavigationItem和UIButton。然后将UIButton添加到UINavigationItem，然后将UINavigationItem添加到UINavigationBar：

   _navBar = [[UINavigationBar alloc] init];
[_navBar setFrame:CGRectMake(0,0,self.view.bounds.size.width,52)];
[self.view addSubview:_navBar];
UINavigationItem *navItem = [[UINavigationItem alloc]initWithTitle:@""];
UIBarButtonItem *barButton = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemRefresh target:self action:@selector(refreshClicked:)];
[navItem setLeftBarButtonItem:barButton];

[_navBar setItems:@[navItem]];

此代码来自以下答案：

---

希望这有帮助。

在实例化UINavigation控制器后，您是否尝试添加它？

我终于发现了问题。在这种情况下非常令人困惑的是，实际的

TNViewcontroller

被包装在

TNPViewController

中。后者是PageViewController。我一直试图在

TNViewController

而不是

TNPViewController

上添加导航项

这是正确的方法，而且有效

家长视图控制器：

TNPViewController *tnp = [[TNPViewController alloc] initWithNews:news index:indexPath.row];
[[self navigationController] pushViewController:tnp animated:YES];

TNPViewController:

- (void)viewDidLoad {
    [super viewDidLoad];
    UIBarButtonItem *refreshButton = [[UIBarButtonItem alloc]
                                      initWithBarButtonSystemItem:UIBarButtonSystemItemRefresh
                                      target:self action:@selector(refreshClicked:)];
    self.navigationItem.rightBarButtonItem = refreshButton;
}

---

但我首先使用的是UINavigationController，对吗？为什么我要手动添加这些？我还没来得及试一试。我想你还不能评论，因为你太新了。新来者通常会感到尴尬。在您的回答中，您没有指定我必须实例化UINavigation控制器。请问我错过了什么？请随意编辑主要答案，我会看到的。