Permissions

Permission lives on the bare @ng-native/expo import, not behind an entry point - it is not bound to one optional module.

Install

Nothing extra: Permission needs no Expo module of its own. Use it against whichever module's permission functions you are calling.

import { Permission } from '@ng-native/expo';

The smallest thing that works

import * as Camera from 'expo-camera';
import { Component, inject } from '@angular/core';
import { Permission } from '@ng-native/expo';

@Component({ selector: 'app-scanner', template: '<text>{{ camera.status() }}</text>' })
export class Scanner {
  protected readonly camera = Permission.of(
    Camera.Camera.getCameraPermissionsAsync,
    Camera.Camera.requestCameraPermissionsAsync,
  );

  protected async scan(): Promise<void> {
    if (await this.camera.ensure()) this.startScanning();
  }

  private startScanning(): void {}
}

Building one

Permission.of(get, request) takes a module's own pair of functions and returns a Permission. Nothing is asked until you call one of the methods below - constructing it does not touch the platform.

readonly notifications = Permission.of(getPermissionsAsync, requestPermissionsAsync);

Reading and asking

• status is a signal: 'granted', 'denied' or 'undetermined' - or 'unknown' before anything has asked the platform, which is not the same as 'undetermined'. 'undetermined' means the platform has been asked and the person has not decided; 'unknown' means nobody has asked yet.
• granted is a signal: whether the permission is currently granted.
• blocked is a signal: true once the platform will no longer show a dialog at all - refused for good. This is the moment to send the person to Settings instead of asking again.
• check() asks the platform what it currently thinks, without showing the person anything.
• request() shows the dialog and resolves to whether they granted it.
• ensure() is the method most call sites want: it has the permission if it can be had, and only shows a dialog if showing one would do something. It checks first if nothing has asked yet, returns true immediately if already granted, returns false immediately if blocked (asking again would resolve to the same no while reading as though the person had been consulted twice), and otherwise shows the request dialog.

protected async open(): Promise<void> {
  if (await this.camera.ensure()) this.scanning.set(true);
}

Reference