How to synchronize an audio on 2 or more ios devices

Question

I have to perform an action (play song at a time on multiple devices without lag) at a given point of time. My requirement is that the app should not use any internet connection

Answer 1

Known Issue

When sleeping or waiting for extremely precise time intervals, timers may be delayed by up to 1 millisecond.

For reference : https://developer.apple.com/library/ios/releasenotes/General/RN-iOSSDK-7.0/