后台位置跟踪不起作用 - Expo - Android

Question

我正在做一些事情，如果应用程序处于后台并且设备处于睡眠状态，我需要跟踪后台位置。我目前让它在后台为应用程序工作，但是当设备处于睡眠状态时它会停止跟踪。我正在为应用程序使用 Expo，并在 Expo Location 旁边使用 Expo Task Manager 在后台获取位置。 任何人都知道如何在应用程序处于后台且设备处于睡眠模式时获取位置？

这是代码

import { StatusBar } from 'expo-status-bar';
import React, { useState, useEffect } from 'react';
import { StyleSheet, Text, View } from 'react-native';
import * as Location from 'expo-location';
import * as TaskManager from 'expo-task-manager';

const App = () => {
  useEffect(() => {
    (async () => await _askForLocationPermission())();
  });

  this.backgroundLocationFetch = async () => {
    const { status } = await Location.requestBackgroundPermissionsAsync();
    if (status === 'granted') {
      console.log('cmon dance with me!')
      await Location.startLocationUpdatesAsync('FetchLocationInBackground', {
        accuracy: Location.Accuracy.Balanced,
        timeInterval: 3000,
        distanceInterval: 1,
        foregroundService: {
          notificationTitle: 'Live Tracker',
          notificationBody: 'Live Tracker is on.'
        }
      });
    }
  }



  const _askForLocationPermission = async () => {
    (async () => {
      let { status } = await Location.requestBackgroundPermissionsAsync();
      if (status !== 'granted') {
        setgpsErrorMsg('Permission to access location was denied');
      }
    })();
  };


  return(
    <View>
      <Text></Text>
    </View>
  )
};

TaskManager.defineTask('FetchLocationInBackground', ({ data, error }) => {
  if (error) {
    console.log("Error bg", error)
    return;
  }
  if (data) {
    const { locations } = data;
    console.log("BGGGG->", locations[0].coords.latitude, locations[0].coords.longitude);
  }
});




export default App;

Answer 1

我遇到了完全相同的问题，并通过使用 EventEmitter 将位置更新分派到 UI 组件来解决这个问题。

文件顶部：

import EventEmitter from 'EventEmitter'

const locationEmitter = new EventEmitter();

didMount：

locationEmitter.on(LOCATION_UPDATE, (locationData) => {
    console.log('locationEmitter locationUpdate fired! locationData: ', locationData);
    let coordinatesAmount = locationData.newRouteCoordinates.length - 1;
    this.setState({
        latitude: locationData.newRouteCoordinates[coordinatesAmount - 1].latitude,
        longitude: locationData.newRouteCoordinates[coordinatesAmount - 1].longitude,
        routeCoordinates: this.state.routeCoordinates.concat(locationData.newRouteCoordinates)
    })
})

componentWillUnmount：

locationEmitter.off(LOCATION_UPDATE);

内部后台任务定义：

locationEmitter.emit(LOCATION_UPDATE, locationData)

这成功从后台任务发送位置数据，但我仍然卡在如何使后台任务更频繁地发送位置更新批次的问题。我的相关帖子是here。