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Expo TaskManager

为可以在后台运行的任务提供支持的库。

Android
iOS
tvOS
Included in Expo Go
Bundled version:
~14.0.9

expo-task-manager 提供了一个 API，使你能够管理长时间运行的任务，特别是那些可以在你的应用处于后台时运行的任务。该库的一些功能在底层被其他库使用。以下是使用 TaskManager 的 Expo SDK 库列表。

使用 Expo TaskManager 的库

🌐 Libraries using Expo TaskManager

安装

🌐 Installation

Terminal
- npx expo install expo-task-manager

If you are installing this in an existing React Native app, make sure to install expo in your project.


信息 你可以在 Expo Go 应用中测试 TaskManager。不过，请查看每个使用 TaskManager 的 库 的文档，以确认它是否支持在 Expo Go 中进行测试。

配置 
iOS

🌐 Configuration 

iOS

独立应用需要一些额外的配置：在 iOS 上，每个后台功能都需要在你的 Info.plist 文件的 UIBackgroundModes 数组中添加一个特殊的键。

🌐 Standalone apps need some extra configuration: on iOS, each background feature requires a special key in UIBackgroundModes array in your Info.plist file.

阅读更多关于如何在使用 TaskManager 的每个 库 的参考中进行配置的信息。

🌐 Read more about how to configure this in the reference for each of the libraries that use TaskManager.

示例

🌐 Example

Example
import React from 'react';
import { Button, View, StyleSheet } from 'react-native';
import * as TaskManager from 'expo-task-manager';
import * as Location from 'expo-location';

const LOCATION_TASK_NAME = 'background-location-task';

const requestPermissions = async () => {
  const { status: foregroundStatus } = await Location.requestForegroundPermissionsAsync();
  if (foregroundStatus === 'granted') {
    const { status: backgroundStatus } = await Location.requestBackgroundPermissionsAsync();
    if (backgroundStatus === 'granted') {
      await Location.startLocationUpdatesAsync(LOCATION_TASK_NAME, {
        accuracy: Location.Accuracy.Balanced,
      });
    }
  }
};

const PermissionsButton = () => (
  <View style={styles.container}>
    <Button onPress={requestPermissions} title="启用后台定位" />
  </View>
);

TaskManager.defineTask(LOCATION_TASK_NAME, ({ data, error }) => {
  if (error) {
    // Error occurred - check `error.message` for more details.
    return;
  }
  if (data) {
    const { locations } = data;
    // do something with the locations captured in the background
  }
});

const styles = StyleSheet.create({
  container: {
    flex: 1,
    alignItems: 'center',
    justifyContent: 'center',
  },
});

export default PermissionsButton;

应用接口

🌐 API

import * as TaskManager from 'expo-task-manager';

Methods

TaskManager.defineTask(taskName, taskExecutor)

Android
iOS
tvOS
ParameterTypeDescription
taskNamestring

Name of the task. It must be the same as the name you provided when registering the task.

taskExecutorTaskManagerTaskExecutor<T>

A function that will be invoked when the task with given taskName is executed.


Defines task function. It must be called in the global scope of your JavaScript bundle. In particular, it cannot be called in any of React lifecycle methods like componentDidMount. This limitation is due to the fact that when the application is launched in the background, we need to spin up your JavaScript app, run your task and then shut down — no views are mounted in this scenario.

Returns:
void

TaskManager.getRegisteredTasksAsync()

Android
iOS
tvOS

Provides information about tasks registered in the app.

Returns:
Promise<TaskManagerTask[]>

A promise which fulfills with an array of tasks registered in the app.

Example

[
  {
    taskName: 'location-updates-task-name',
    taskType: 'location',
    options: {
      accuracy: Location.Accuracy.High,
      showsBackgroundLocationIndicator: false,
    },
  },
  {
    taskName: 'geofencing-task-name',
    taskType: 'geofencing',
    options: {
      regions: [...],
    },
  },
]

TaskManager.getTaskOptionsAsync(taskName)

Android
iOS
tvOS
ParameterTypeDescription
taskNamestring

Name of the task.


Retrieves options associated with the task, that were passed to the function registering the task (e.g. Location.startLocationUpdatesAsync).

Returns:
Promise<TaskOptions>

A promise which fulfills with the options object that was passed while registering task with given name or null if task couldn't be found.

TaskManager.isAvailableAsync()

Android
iOS
tvOS

Determine if the TaskManager API can be used in this app.

Returns:
Promise<boolean>

A promise which fulfills with true if the API can be used, and false otherwise. With Expo Go, TaskManager is not available on Android, and does not support background execution on iOS. Use a development build to avoid limitations: https://expo.fyi/dev-client. On the web, it always returns false.

TaskManager.isTaskDefined(taskName)

Android
iOS
tvOS
ParameterTypeDescription
taskNamestring

Name of the task.


Checks whether the task is already defined.

Returns:
boolean

TaskManager.isTaskRegisteredAsync(taskName)

Android
iOS
tvOS
ParameterTypeDescription
taskNamestring

Name of the task.


Determine whether the task is registered. Registered tasks are stored in a persistent storage and preserved between sessions.

Returns:
Promise<boolean>

A promise which resolves to true if a task with the given name is registered, otherwise false.

TaskManager.unregisterAllTasksAsync()

Android
iOS
tvOS

Unregisters all tasks registered for the running app. You may want to call this when the user is signing out and you no longer need to track his location or run any other background tasks.

Returns:
Promise<void>

A promise which fulfills as soon as all tasks are completely unregistered.

TaskManager.unregisterTaskAsync(taskName)

Android
iOS
tvOS
ParameterTypeDescription
taskNamestring

Name of the task to unregister.


Unregisters task from the app, so the app will not be receiving updates for that task anymore. It is recommended to use methods specialized by modules that registered the task, eg. Location.stopLocationUpdatesAsync.

Returns:
Promise<void>

A promise which fulfills as soon as the task is unregistered.

Interfaces

TaskManagerError

Android
iOS
tvOS

Error object that can be received through TaskManagerTaskBody when the task fails.

PropertyTypeDescription
codestring | number
-
messagestring
-

TaskManagerTask

Android
iOS
tvOS

Represents an already registered task.

PropertyTypeDescription
optionsany

Provides options that the task was registered with.

taskNamestring

Name that the task is registered with.

taskTypestring

Type of the task which depends on how the task was registered.

TaskManagerTaskBody

Android
iOS
tvOS

Represents the object that is passed to the task executor.

PropertyTypeDescription
dataT

An object of data passed to the task executor. Its properties depend on the type of the task.

errornull | TaskManagerError

Error object if the task failed or null otherwise.

executionInfoTaskManagerTaskBodyExecutionInfo

Additional details containing unique ID of task event and name of the task.

TaskManagerTaskBodyExecutionInfo

Android
iOS
tvOS

Additional details about execution provided in TaskManagerTaskBody.

PropertyTypeDescription
appState(optional)'active' | 'background' | 'inactive'
Only for: 
iOS

State of the application.

eventIdstring

Unique ID of task event.

taskNamestring

Name of the task.

Types

TaskManagerTaskExecutor(body)

Android
iOS
tvOS

Type of task executor – a function that handles the task.

ParameterType
bodyTaskManagerTaskBody<T>
Returns:

Promise<any>