iOS AppDelegate 订阅者

了解如何使用 Expo 模块 API 订阅与应用相关的 iOS 系统事件，例如入站链接和通知。

为了响应与应用相关的某些 iOS 系统事件，例如入站链接和通知，需要处理 AppDelegate 中的相应方法。

¥To respond to certain iOS system events relevant to an app, such as inbound links and notifications, it is necessary to handle the corresponding methods in the AppDelegate.

React Native 模块 API 不提供任何机制来钩子这些方法，因此 React Native 库的设置指令通常包括将代码复制到 AppDelegate 文件中的步骤。为了简化和自动化设置和维护，Expo Modules API 提供了一种机制，允许你的库订阅对 AppDelegate 函数的调用。为此，应用 AppDelegate 必须继承自 ExpoAppDelegate，这是使用 Expo 模块的要求。

¥The React Native module API does not provide any mechanism to hook into these methods, and so setup instructions for React Native libraries often include a step to copy code into the AppDelegate file. To simplify and automate setup and maintenance, the Expo Modules API provides a mechanism that allows your library to subscribe to calls to AppDelegate functions. For this to work, the app AppDelegate must inherit from ExpoAppDelegate, and this is a requirement for using Expo Modules.

ExpoAppDelegate 实现 UIApplicationDelegate 协议的大部分功能，并将其调用转发给所有订阅者。

¥ExpoAppDelegate implements most functions from UIApplicationDelegate protocol and forwards their calls to all the subscribers.

开始使用

¥Get started

首先，你需要创建一个 Expo 模块或使用 React Native 模块 API 将 Expo 模块 API 集成到库中。了解更多。

¥First, you need to have created an Expo module or integrated the Expo modules API in library using the React Native module API. Learn more.

创建一个新的公共 Swift 类，该类从 ExpoModulesCore 扩展 ExpoAppDelegateSubscriber，并将其名称添加到 模块配置 中的 ios.appDelegateSubscribers 数组中。运行 pod install，订阅者将在应用项目内的 ExpoModulesProvider.swift 文件中生成。

¥Create a new public Swift class that extends ExpoAppDelegateSubscriber from ExpoModulesCore and add its name to the ios.appDelegateSubscribers array in the module config. Run pod install, and the subscriber will be generated in the ExpoModulesProvider.swift file within the application project.

现在，你可以通过向订阅者类添加委托函数来订阅事件。有关你可以订阅的函数的完整列表，请参阅 ExpoAppDelegate.swift 中覆盖的函数。尚不支持提供时可能会导致副作用的应用委托函数（例如，application(_:viewControllerWithRestorationIdentifierPath:coder:)）。

¥Now you can subscribe to events by adding delegate functions to your subscriber class. For the full list of functions that you can subscribe to, see the functions that are overridden in ExpoAppDelegate.swift. App delegate functions that may cause side effects when provided are not supported yet (for example, application(_:viewControllerWithRestorationIdentifierPath:coder:)).

不支持 Objective-C 类。

¥Objective-C classes are not supported.

结果值

¥Result values

需要返回值的委托函数有一些额外的逻辑来协调来自多个订阅者的响应并尝试满足所有这些响应。这种边缘情况有两个很好的例子：

¥Delegate functions that need to return a value have some additional logic to reconcile responses from multiple subscribers and try to satisfy all of them. There are two good examples of such edge cases:

application(_:didFinishLaunchingWithOptions:) -> Bool

根据 苹果文档，如果应用无法处理 URL 资源或继续用户活动，则应返回 false，否则应返回 true。如果应用因远程通知而启动，则返回值将被忽略。在这种情况下，如果至少一个订阅者返回 true，则 ExpoAppDelegate 也会返回 true。

¥According to the Apple documentation, you should return false if the app cannot handle the URL resource or continue a user activity, otherwise true should be returned. The return value is ignored if the app is launched because of a remote notification. In such situations, if at least one of the subscribers returns true, the ExpoAppDelegate will return true as well.

application(_:didReceiveRemoteNotification:fetchCompletionHandler:)

此方法告诉应用委托远程通知已到达，并使应用有机会获取新数据。它接收一个完成块，在获取操作完成时执行。应使用最能描述提取请求结果的提取结果值来调用此块。可能的值为：UIBackgroundFetchResult.newData、UIBackgroundFetchResult.noData 或 UIBackgroundFetchResult.failed。在这种情况下，ExpoAppDelegate 将新的完成块传递给每个订阅者，等待所有完成并在调用原始完成块之前收集结果。最终结果取决于订阅者收集的结果，按以下顺序排列：

¥This method tells the app delegate that a remote notification arrived and gives the app the opportunity to fetch new data. It receives a completion block to execute when the fetch operation is completed. This block should be called with the fetch result value that best describes the results of your fetch request. Possible values are: UIBackgroundFetchResult.newData, UIBackgroundFetchResult.noData or UIBackgroundFetchResult.failed. In this scenario, ExpoAppDelegate passes a new completion block to each subscriber, waits until all are completed and collects the results before calling the original completion block. The final result depends on the results collected from the subscribers, as follows in the following order:

• 如果至少有一个订阅者使用 failed 结果调用完成块，则委托也会返回 failed。

  ¥If at least one subscriber called the completion block with failed result, the delegate returns failed as well.

• 如果至少有一个 newData 结果，则委托返回 newData。

  ¥If there is at least one newData result, the delegate returns newData.

• 否则返回 noData。

  ¥Otherwise noData is returned.

要查看其他函数如何处理订阅者的结果，我们建议直接阅读代码：ExpoAppDelegate.swift。

¥To check out how other functions process the result of your subscriber, we recommend reading the code directly: ExpoAppDelegate.swift.

示例

¥Example

import ExpoModulesCore

public class AppLifecycleDelegate: ExpoAppDelegateSubscriber {
  public func applicationDidBecomeActive(_ application: UIApplication) {
    // The app has become active.
  }

  public func applicationWillResignActive(_ application: UIApplication) {
    // The app is about to become inactive.
  }

  public func applicationDidEnterBackground(_ application: UIApplication) {
    // The app is now in the background.
  }

  public func applicationWillEnterForeground(_ application: UIApplication) {
    // The app is about to enter the foreground.
  }

  public func applicationWillTerminate(_ application: UIApplication) {
    // The app is about to terminate.
  }
}

{
  "ios": {
    "appDelegateSubscribers": ["AppLifecycleDelegate"]
  }
}