iPhone: How to play sound that ignores volume and ringer switch settings?

The app FoneHome is able to do both:

• ignore the ringer switch when it's set to silence
• play at a high volume regardless of system volume setting

I see documentation about th开发者_如何学Goe playback Audio Session category not respecting the ringer switch but not the volume. Can someone enlighten me?

It is technically possible to change the system volume through the private AVSystemController class in Celestial.framework, but causes problems with Apple's approval process. FoneHome recently was taken down - its possible that the back and forth between them and Apple was because of this reason.