RightBarButtonItem 仅显示为非活动状态

Question

我在尝试将刷新按钮显示为 rightBarButtonItem 时遇到一个奇怪的问题。

总之，我已经实现了，但是运行应用程序什么都看不到。然而，当我点击故事板时 Debug --> View Debugging --> Capture View Hierarchy。我可以看到一个似乎不活动且隐藏的刷新按钮。我不知道为什么。

viewcontrol 实际上是通过自定义 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;
}

请问我错过了什么？

Answer 1

因为您要将它添加到 uiviewcontroller，所以您需要创建 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]];

此代码来自此处找到的答案：

adding barButtonItems to a UINavigationBar without a Navigation Controller

希望对您有所帮助。

Answer 2

您是否尝试在实例化 NavigationController 后添加它？

Answer 3

终于找到问题了。在这种情况下非常令人困惑的是，实际的 TNViewcontroller 被包裹在 TNPViewController 中。后者是 PageViewController。我一直试图在 TNViewController 而不是 TNPViewController 上添加 navigationItem。

这是正确的方法，而且有效。

ParentViewController:

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;
}

RightBarButtonItem 仅显示为非活动状态

RightBarButtonItem shows only as inactive

ios

uinavigationbar

rightbarbuttonitem