Keep awake

It is never a bare activate: a screen that holds the display on and never releases it is a phone that never sleeps, which the user experiences as a battery fault and never attributes to the app that caused it. hold() always returns the function that releases it.

Install

npx expo install expo-keep-awake

import { KeepAwake } from '@ng-native/expo/keep-awake';

The smallest useful example

import { Component, DestroyRef, inject } from '@angular/core';
import { Text } from '@ng-native/components';
import { KeepAwake } from '@ng-native/expo/keep-awake';

@Component({
  selector: 'app-recording',
  imports: [Text],
  template: `<text>Recording...</text>`,
})
export class Recording {
  constructor() {
    inject(DestroyRef).onDestroy(inject(KeepAwake).hold('recording'));
  }
}

What it does

• hold(tag) - holds the screen on under that tag, and returns the function that releases it. The tag defaults to a package-wide constant. Holds are counted per tag, so two screens holding the same tag, or the default, each keep the screen on until their own hold is released; naming the tag is what tells them apart in holders.
• holders - a signal of the set of tags currently holding the screen on, for a debug screen that wants to say which.
• active - whether anything currently holds the screen on, computed from whether holders is non-empty.

Releasing the same hold twice does nothing the second time. Holds are counted across every app the runtime mounts, and an app that is destroyed releases the holds it still has. On Android, each time an activity comes to the front, a recreated one included, every held tag is released and taken again. A new activity starts with its screen free to sleep, and expo-keep-awake, which keeps its tags for as long as the runtime runs, turns the screen on only when its first tag comes.

Without the module

On iOS and Android, a missing expo-keep-awake - never installed, or installed without the app being rebuilt since - leaves the service made, so injecting it does not throw. A call, or a read of a value only the module knows, throws a MissingModuleError. Its message names the module and the commands that fix it; see Using a module.

On the web, and in a test that provides no fake, hold() still tracks the tag in holders and active, but nothing on the device changes and stop calls into a module that is not there safely.

Reference