NSURLSession upload task with background session

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Created Mar ’18

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Our app uses significant updates to create a upload task when the app is in background, this works fine for sometime.But after few days (5-8) this stops working and all the data are sent only when app is brought to foreground, is there a known limitation with upload task with background session.

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Answer 1

DTS Engineer OP

Apple

Mar ’18

NSURLSession

background sessions use a complex algorithm to decide when to run the tasks scheduled in that session. This algorithm is not documented because it changes over time. Once such change occurred in iOS 8, which boosts the priority of background session task when your app is in the foreground, which is why you see things unblock when the app is brought to the front.

The best way forward here depends on your specific requirements. Most folks in this situation are uploading tiny amounts of data, in which case using a standard session is probably the best option. You can read more about this idea in this thread.

IMPORTANT This approach makes heavy use of UIApplication background tasks. I recommend that you read up on those before starting down this path.

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