A customer had set the following task: he wanted to receive data to his device from the server in the local network regardless of whether the application was in foreground mode or not.
Previously, the applications were simply killed when the Home button was pressed. But starting with iOS version 4.0, the applications featured a so-called background mode, which automatically pauses all tasks by default (except for those with delays, which should be stopped manually or which will actuate simultaneously in case of return to the application when the delay expires).
In order to execute a code in the background, it is necessary to observe several conditions which the given application should correspond to.