background task snippet

background-task-code-snippet.js

import BackgroundTask from 'react-native-background-task'
import queueFactory from 'react-native-queue';

BackgroundTask.define(async () => {

  // Init queue
  queue = await queueFactory();

  // Register job worker
  queue.addWorker('pre-fetch-image', async (id, payload) => {

    Image.prefetch(payload.imageUrl);

  });

  // Start the queue with a lifespan
  // IMPORTANT: OS background tasks are limited to 30 seconds or less.
  // NOTE: Queue lifespan logic will attempt to stop queue processing 500ms less than passed lifespan for a healthy shutdown buffer.
  // IMPORTANT: Queue processing started with a lifespan will ONLY process jobs that have a defined timeout set.
  // Additionally, lifespan processing will only process next job if job.timeout < (remainingLifespan - 500).
  await queue.start(25000); // Run queue for at most 25 seconds.

  // finish() must be called before OS hits timeout.
  BackgroundTask.finish();

});