How to implement background execution of tasks?

Question

Swift

Hello. Can you please tell me how to implement the ability to run a certain function of the application (for example, checking the number of new messages and displaying a new notification) in the background in Swift 3? So that this function works not only when the application is minimized, but also when it is not even running. I dealt with Background Fetch, but the interval is set there is generally incomprehensible, the function is either executed or not. In addition, I'm not sure that it will work when the application is not even running. I ask you to direct me in the right direction and share a detailed manual, thanks.

Answer 1

iOS apps have a very rigid approach to background mode. Background fetch is really suitable for your tasks. However, there are 2 points:
1. The system itself chooses the frequency of launching the application. You can influence her "preferences" by making a request as soon as possible and returning a message that you have downloaded new data.
2. an application that the user killed with his hands (thrown out of the tray) will not start at all for fetch.
Because of all this, the correct approach is for the server to notify the application through pushes, rather than the application itself verifying the data.