What is the best way to schedule a task in react native?

Question

There are different ways to run tasks in the background in Android and iOS respectively. I have found What is the best way to schedule task in android? as well on stack overflow.

I am wondering which is the best way using react-native only. Would it be good enough to use setInterval or setTimeout for tasks that have to run daily or every few hours?

Would not those tasks be killed by the OS?

Any ideas or suggestions?

Answer 1

I will answer my own question to see if this information can be of used by anyone looking for it.

Since the different mobile OSs tend to kill background jobs, or stall them to save battery, there are few deterministic methods to schedule tasks in react native. I use a combination of the following:

• Offload timers to the background, which work with the app in both fore and background https://github.com/ocetnik/react-native-background-timer (!If you use create-react-native-app you must eject it)

• Use a background-fetch for iOS and HeadlessTask in Android, here is a decent library https://github.com/jamesisaac/react-native-background-task

• Use geolocation updates to wake up the app and start threads https://github.com/mauron85/react-native-background-geolocation.

• I guess you can follow similar strategies using bluetooth wake-ups.

• Push notifications from a server to ensure deterministically that the app wakes app (except it having been killed by the OS). In iOS, ensure that you call notification.finish() to avoid being discriminated by the task handler algorithm.

• For Android you can try to use AlarmManager API https://github.com/vikeri/react-native-background-job.

Beware of the dragons: your app might be closed if it abuses execution time or memory usage after a system wake up. You may have to rehydrate all listeners after the phone was left without battery. So the user still needs to interact heavily with your app.

Update: From Android O there are very strict background execution limits. When using a HeadlessJSTask service, ensure that it is launched as a foreground service if you want it to last longer than a few seconds. It may require a notification with it. Take into account that only loading the bundle can take up to a few seconds, depending on your app and the device.