Summary - Permissions

Combine expo-permissions and camera/location permissions to write a permission flow.

Summary - Permissions

In this group you learned the foundation of permissions. A permission is the system approval gate for a sensitive resource. expo-permissions is Expo's permission module; it is requested with askAsync.

Camera permission uses Permissions.CAMERA, location permission uses Permissions.LOCATION, notification permission uses Permissions.NOTIFICATIONS. In each you check status and route the flow: if 'granted' continue, otherwise guide the user. These five concepts together form the permission flow of a real mobile app. To keep user trust, asking at the right moment is essential.

Exercise Write the usePermissions hook

Write a usePermissions hook. It takes a permissionType parameter. Hold status with useState('undetermined'). Inside useEffect call Permissions.askAsync(permissionType); in .then call setStatus. Return status.

Show example solution

import { useState, useEffect } from "react";
import * as Permissions from "expo-permissions";

export function usePermissions(permissionType) {
  const [status, setStatus] = useState("undetermined");
  useEffect(() => {
    Permissions.askAsync(permissionType).then(({ status }) => {
      setStatus(status);
    });
  }, [permissionType]);
  return status;
}

Test yourself

Which permission is needed for location data?
```
Permissions.???
```
- Camera
- Notification
- Location
- Microphone
Show answer

Location — Location data needs location permission.
Match each permission to its resource

Permissions.CAMERA

Camera
Permissions.LOCATION

GPS
Permissions.NOTIFICATIONS

Push notification
askAsync

Asks permission

expo-permissions import

import * as Permissions from '____';

Show answer

import * as Permissions from 'expo-permissions';

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