expo-location 在 ios 中不起作用，并且在应用程序设置中不显示位置权限

Question

I am trying to get current location in IOS 14, but i am getting no response and when i check in expo settings it's not showing location permission there. I have checked in both simulator and physical device.

Hook Code

import { useEffect, useState } from "react";
import * as Location from "expo-location";

export default useLocation = () => {
  const [location, setLocation] = useState();

  const getLocation = async () => {
    try {
      const { granted } = await Location.requestPermissionsAsync();
      if (!granted) return;
      const {
        coords: { latitude, longitude },
      } = await Location.getLastKnownPositionAsync();
      setLocation({ latitude, longitude });
    } catch (error) {
      console.log(error);
    }
  };

  useEffect(() => {
    getLocation();
  }, []);

  return location;
};

Response

undefined

Answer 1

The docs says Location.getLastKnownPositionAsync() might return null:

Returns a promise resolving to an object of type LocationObject or null if it's not available or doesn't match given requirements such as maximum age or required accuracy.

so you should do something like:

import { useEffect, useState } from "react";
import * as Location from "expo-location";

export default useLocation = () => {
  const [location, setLocation] = useState();

  const getLocation = async () => {
    try {
      const { granted } = await Location.requestPermissionsAsync();
      if (!granted) return;
      const last = await Location.getLastKnownPositionAsync();
      if (last) setLocation(last);
      else {
        const current = await Location.getCurrentPositionAsync();
        setLocation(current);
      }
    } catch (error) {
      console.log(error);
    }
  };

  useEffect(() => {
    getLocation();
  }, []);

  return location;
};

Answer 2

use requestForegroundPermissionAsync() instead of requestPermissionAsync. and the problem is solved.