A third-party library provides a function I need to call every 100ms. Setting up a timer to do that works very well as long as my app is on foreground. When my app is on background timer works for a while but after a about a minute timer is called only after 10 second delay. The same happened when I created a separate thread with usleep-function. Is there any way I can keep timer running while my app is on background?
Use beginActivityWithOptions:reason: to disable app nap for your application.
You should try and re-architect to avoid these sorts of frequent timers, especially when your application is in the background. Making this sort of change will improve battery life for your users.
来源：https://stackoverflow.com/questions/20607290/os-x-cocoa-timer-not-fired-when-application-on-background