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?

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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.