如何在 React Native / Expo 中请求权限？

Question

I am trying to request a user's location. I tried writing an async function to tell me if my request was processed, but it is ignored. I am prompted with a "location request" but I believe it is actually the Expo app and not my function.

Below is some of my code:

import React, { useState, useEffect, Component }from "react";

import { Permissions , Request } from 'expo-permissions'

//This is the async function I wrote to prompt the user to give permission

async function getLocationAsync(){
  const { status, permissions } = await Permissions.askAsync( Permissions.LOCATION);
if (status === 'granted'){
console.log('It worked!')
} 
else {
  throw new Error('Location permission not granted');
  }
}

//This logs the terminal and lets me know that the user's current location has been isolated (mounting). When the app no longer needs their location, it dismounts to prevent a memory leak.

const Screen = ({navigation})=> { 
    const [user_latitude, setUserLatitude] = useState(0)
    const [user_longitude, setUserLongitude] = useState(0)
    const [position_error, setPositionError] = useState(null)


useFocusEffect( 
      React.useCallback(()=> {
        
      let isActive = true;

      const fetchGeoPosition = () => {
        navigator.geolocation.getCurrentPosition(
        position => { 
          if (isActive){

          setUserLatitude(position.coords.latitude);
          setUserLongitude(position.coords.longitude);
          setPositionError(null);


          console.log('Location Accessed')

          
        } 
        setIsLoading(false)

      }, 

      error => isActive && setPositionError(error.message),
      {enableHighAccuracy: true, timeout: 0, maximumAge: 1000} 
      ); 
    }

    fetchGeoPosition()

      return () =>{
        isActive = false
        console.log('Location Severed')
          }
        }, 
      [],
       ),
    )
    
 

Answer 1

Check this library for Permission on react-native

Here's https://www.npmjs.com/package/react-native-permissions .

For Android only there a default Package in react-native. ( PermissionAndroid)

https://reactnative.dev/docs/permissionsandroid

Update your manifest file also. Indicating that the application going to use external resource which requires user permission.

https://developer.android.com/guide/topics/manifest/uses-permission-element

And For iOS update info.plist file

https://www.iosdev.recipes/info-plist/permissions/