Notification audio file from Unity project

I am just wandering if its possible to add and audio file (alert.mp3) inside the unity project for use with push notifications on iOS, and when building to Xcode, this file will be in the Xcode project.

I am a little tired of, when rebuilding a project I have to import the file inside the Xcode project (I sometimes forget :-/).

I tried to add the file inside "plugins -> ios" but with no luck.

Hope this is doable and thanks for any reply