Can't get background tasks to work in React-Native

I need to frequently write into a text file, let's say write a timestamp into a file with react-native in iOS and android. I wrote an app by the help of the following libraries. On android, the app is working perfectly fine, but on iOS not working properly.

I tried to use these libraries:

1. react-native-background-task
2. react-native-background-fetch
3. react-native-background-queue + react-native-background-task

But none of them works fine:

1. with react-native-background-task: the file is written randomly 5-6times a day or less
2. with react-native-background-fetch: the file is written randomly 3-4 times a day or less
3. react-native-background-queue + react-native-background-task: thefile is not written AT ALL!

Would you please tell me if these behaviors are normal, and if not, what am I doing wrong???

Any help would be greatly appreciated.

Here are my codes:

In order to use react-native-background-task:

import React from 'react'import Mytest from './test';import BackgroundTask from 'react-native-background-task'import {    Text,    View,  } from 'react-native';BackgroundTask.define(() => {  console.log('Hello from a background task')  Mytest.writeFiles()  BackgroundTask.finish()})export default class MyApp extends React.Component {  componentDidMount() {    BackgroundTask.schedule()  }  render() {    return(<View><Text>Hello world</Text></View>)  }}

In order to use react-native-background-fetch:

import React, { Component } from 'react';import {    Text,    View,    StyleSheet  } from 'react-native';import BackgroundFetch from "react-native-background-fetch";var RNFS = require('react-native-fs');var path = RNFS.DocumentDirectoryPath +'/fetch.txt';var count = 0export default class App extends Component {  constructor(props) {    super(props);    this.state = {      date: '',    }  }  componentDidMount() {    BackgroundFetch.configure({      stopOnTerminate: false,      startOnBoot: true,      requiredNetworkType: BackgroundFetch.NETWORK_TYPE_NONE,      requiresCharging: false,      // Default      requiresDeviceIdle: false,    // Default      requiresBatteryNotLow: false, // Default      requiresStorageNotLow: false  // Default    }, () => {      console.log("[js] Received background-fetch event");      this.writeFiles()      BackgroundFetch.finish(BackgroundFetch.FETCH_RESULT_NEW_DATA);    }, (error) => {      console.log("[js] RNBackgroundFetch failed to start");    });    BackgroundFetch.status((status) => {      switch(status) {        case BackgroundFetch.STATUS_RESTRICTED:          console.log("BackgroundFetch restricted");          break;        case BackgroundFetch.STATUS_DENIED:          console.log("BackgroundFetch denied");          break;        case BackgroundFetch.STATUS_AVAILABLE:          console.log("BackgroundFetch is enabled");          break;      }    });  }  render() {        return (<View style={styles.container}><Text style={styles.welcome}>              Welcome to React Native!</Text></View>        );      }  getDate() {    var that = this;    var date = new Date().getDate(); //Current Date    var month = new Date().getMonth() + 1; //Current Month    var year = new Date().getFullYear(); //Current Year    var hours = new Date().getHours(); //Current Hours    var min = new Date().getMinutes(); //Current Minutes    var sec = new Date().getSeconds(); //Current Seconds    that.setState({      date:        date +'/'+ month +'/'+ year +''+ hours +':'+ min +':'+ sec,    });  }writeFiles = async () => {  this.getDate()    try {      for(let i = 0; i < 1; i++){        count = count + 1;        console.log(count);        RNFS.appendFile(path, '  \n  '+ count +'  \n  '+ this.state.date , 'utf8')        .then((success) => {        })      }    }catch (err) {      console.warn("error", err);    } }          };

In order to use react-native-background-queue + react-native-background-task:

import React, { Component } from 'react';import Mytest from './test';import BackgroundTask from 'react-native-background-task'import {Platform,...} from 'react-native';import queueFactory from 'react-native-queue';BackgroundTask.define(async () => {  queue = await queueFactory();  queue.addWorker('background-example', async (id, payload) => {  if (payload.name == 'sima') {     Mytest.writeFiles()     console.log('Hello from a background task ')}  });  await queue.start(20000);   BackgroundTask.finish();});export default class App extends Component<{}> {  constructor(props) {    super(props);    this.state = {      queue: null,      data: null,    };    this.init();  }  async init() {    const queue = await queueFactory();    queue.addWorker('background-example', async (id, payload) => {    });    this.setState({      queue    });  }  componentDidMount() {    BackgroundTask.schedule();   }  makeJob(jobName, payload = {}) {    console.log('job is created but will not execute until the above OS background task runs in ~15 min');    this.state.queue.createJob(jobName, payload, {     timeout: 5000    }, false);   }  render() {    let output = 'No data loaded from OS background task yet.';    if (this.state.data) {      output = JSON.stringify(this.state.data);    }    return (<View style={styles.container}><Text style={styles.welcome}>          Welcome to React Native!</Text><Text>Click buttons below to add OS background task jobs.</Text><Text>Then Close App (task will not fire if app is in focus).</Text><Text>Job will exec in ~15 min in OS background.</Text>        {this.state.queue && <Button title={"Press To Queue sima Job"} onPress={ () => { this.makeJob('background-example', { name: 'sima' }) } } /> }        {this.state.queue && <Button title={"Press To Queue another Job"} onPress={ () => { this.makeJob('background-example', { name: 'simsim' }) } } /> }<Text>{output}</Text></View>    );  }}const styles = StyleSheet.create({  container: {    flex: 1,    justifyContent: 'center',    alignItems: 'center',    backgroundColor: '#F5FCFF',  },  welcome: {    fontSize: 20,    textAlign: 'center',    margin: 10,  },});

And here is test.js:

var RNFS = require('react-native-fs');var path = RNFS.DocumentDirectoryPath +'/test.txt';var count = 0;const Mytest = {  writeFiles: () => {    var that = this;    var date = new Date().getDate(); //Current Date    var month = new Date().getMonth() + 1; //Current Month    var year = new Date().getFullYear(); //Current Year    var hours = new Date().getHours(); //Current Hours    var min = new Date().getMinutes(); //Current Minutes    var sec = new Date().getSeconds(); //Current Seconds    var date = date +'/'+ month +'/'+ year +''+ hours +':'+ min +':'+ sec      try {        for(let i = 0; i < 1; i++){          count = count + 1;          console.log(count);          RNFS.appendFile(path, '  \n  '+ count +'  \n  '+ date , 'utf8')          .then((success) => {            console.log('FILE WRITTEN!');          })        }      }catch (err) {        console.warn("error", err);      }   }  }  export default Mytest;