CODEWITHSUNDEEP
iosbackground-mode
potato
potato

Reputation: 4589

battery consuming tasks when launched in the background

Apple states that the app using the background mode shouldn't perform expensive, battery consuming tasks when launched in the background. What exactly is considered a batter consuming task? To be specific: is searching and array of 100 entries acceptable? What about 1000?

Upvotes: 1

Views: 110

Answers (2)

Tobi Nary
Tobi Nary

Reputation: 4596

The remark from the guidelines you are referencing is meant to keep people form draining a user's battery in the background.

As a lot of applications use GPS and/or radio in the background and those are way more power consuming than searching tiny arrays, searching some array will probably be fine, as long as it has a reasonable size.

You shouldn't create an app that helps SETI or Folding or searches for the next biggest prime - or excessively use radio. But for small tasks like your's, this guideline is not to be concerned. Yet, this is only an estimate and in the end, the review process will decide on this on a case by case basis.

The general rule of thumb from apple is:

Always try to avoid doing any background work unless doing so improves the overall user experience. An app might move to the background because the user launched a different app or because the user locked the device and is not using it right now. In both situations, the user is signaling that your app does not need to be doing any meaningful work right now. Continuing to run in such conditions will only drain the device’s battery and might lead the user to force quit your app altogether. So be mindful about the work you do in the background and avoid it when you can.

So the question for you to decide if this is okay is: Does the user expect that to be done right now? rather than does that use too many battery?. If searching that array cannot be deferred to when the app is active again (I cannot see a reason for not deferring it, but there might be), you are fine searching the array in background.

Upvotes: 1

Sergey Kalinichenko
Sergey Kalinichenko

Reputation: 726479

A battery-consuming task is just that - a task that uses so much CPU that it makes considerable "dent" on the battery, as measured by the "battery percentage" screen. To that end, searching 100, 1000, or 1000000 items a single time is unlikely to do any damage. On the other hand, searching a 10-item list fifty times a second is very likely to make your task a high energy consumer. Same goes for downloading data multiple times per minute, using location services, etc.

A rule of thumb is very simple: go to the "Last 24 hours" view of the "Battery percentage" screen, and see if your app is listed there. If it is not there, of if it is below "Home & Lock Screen", your app is fine.

Upvotes: 2

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