当我触摸选项卡栏项目时，我没有收到任何通知
我有 UITabbarCoo=ntroller 应用程序。我添加了观察者，正在等待任何通知。当我触摸选项卡栏项目时，我没有收到任何通知。
[self.tabBarController addObserver:self forKeyPath:@"selectedIndex" options:NSKeyValueObservingOptionNew context:@"changedTabbarIndex"];
- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context
{
NSString *action = (NSString*)context;
if([action isEqualToString:@"changedTabbarIndex"])
{
}
}
I have UITabbarCoo=ntroller application. I added an observer and I'm waiting for any notifications. I didn't get any notifications when I touched on tabbar items.
[self.tabBarController addObserver:self forKeyPath:@"selectedIndex" options:NSKeyValueObservingOptionNew context:@"changedTabbarIndex"];
- (void)observeValueForKeyPath:(NSString *)keyPath ofObject:(id)object change:(NSDictionary *)change context:(void *)context
{
NSString *action = (NSString*)context;
if([action isEqualToString:@"changedTabbarIndex"])
{
}
}
如果你对这篇内容有疑问，欢迎到本站社区发帖提问 参与讨论，获取更多帮助，或者扫码二维码加入 Web 技术交流群。
绑定邮箱获取回复消息
由于您还没有绑定你的真实邮箱，如果其他用户或者作者回复了您的评论，将不能在第一时间通知您！
发布评论
评论（1）
我注意到同样的事情。我认为这是 UITabBarController 实现中的一个错误。请注意，使用
selectedViewController的键路径而不是selectedIndex确实会导致 KVO 通知被触发。但要小心。如果您的 UITabBarController 有一个 UIMoreNavigationController （用于“更多”选项卡），当用户选择“更多”选项卡时您将收到 KVO 通知，但您不会当用户选择 UIMoreNavigationController 的子视图控制器时收到任何通知。这是因为 UIMoreNavigationController 是一个单独的视图控制器，因此当您选择其子视图控制器之一时，UITabBarController 的
selectedViewController不会更改 – 它实际上是 UIMoreNavigationController 的topViewController> 这会改变。如果除了 UITabBarController 的
selectedViewController属性之外，您还可以观察 UIMoreNavigationController 的topViewController属性，那就太好了，但此属性似乎也不会导致 KVO 通知被触发。但是，您可以在 UIMoreNavigationController 上设置委托并实现navigationController:didShowViewController:animated:方法。摘要：观察 UITabBarController 的
selectedViewController属性，如果您的应用程序有“更多”选项卡，请在选项卡栏控制器的moreNavigationController上设置委托> 财产。I noticed the same thing. I assume that this is a bug in the UITabBarController implementation. Note that using a key path of
selectedViewControllerinstead ofselectedIndexdoes cause KVO notifications to be fired.But be careful. If your UITabBarController has a UIMoreNavigationController (for the "More" tab), you will get the KVO notification when the user selects the "More" tab, but you won't get any notifications when the user selects a child viewcontroller of the UIMoreNavigationController. This is because the UIMoreNavigationController is a separate view controller, so when you select one of its child view controllers, the UITabBarController's
selectedViewControllerisn't changing – it's actually the UIMoreNavigationController'stopViewControllerthat changes.It would be great if you could then observe the UIMoreNavigationController's
topViewControllerproperty in addition to the UITabBarController'sselectedViewControllerproperty, but this property does not appear to cause KVO notifications to be fired either. However, you can set a delegate on the UIMoreNavigationController and implement thenavigationController:didShowViewController:animated:method.Summary: observe the
selectedViewControllerproperty of the UITabBarController, and if your application has a "More" tab, set a delegate on the tab bar controller'smoreNavigationControllerproperty.