How to organize periodic sending of data to the server


I want to implement the functionality where the user can turn on mode, which sends, request to the server and receives the information, on average, every minute. The information may contain a prescription, you need to make another request or wait another minute and send request to server again, the mode must poll the server and carry out the appropriate prescription, even if the user application will turn to background (not turn off)

I know a bit about background modes, for me (as I understand) background fetch, or executing finite-length tasks. But once the amendment, in the background fetch I can set the query interval, setMinimumBackgroundFetchInterval, which does not guarantee average one minutes. And doubts about executing finite-length tasks that I need to perform 2-3 queries (realized through NSTimer), and in itself is not long task.

How should I organize the work in the background? What should I use? Maybe I should do is perform through NSURLSession, but then what i should to search?

Thank you for help,