Make use of IOS volume buttons

Hi there Me and my team are almost finished with our game. However, we thought about adding a feature to play a part using the volume buttons on mobile. A blueprint for android already exists and for ios objective c code can be used. But after all-will apple reject it. There are camera apps and stop watches using this feature why not games?
Would the probability of not being rejected increase by mentioning that it is an OPTIONAL feature-not mandatory?
Thank you Unreal engine community for coming this far.
Release is soon maybe within this month.