iOS already gives users a simple per-app Microphone permission:
Settings → Apps → [App] → Microphone: On/Off
Why isn’t there an equivalent permission in the other direction?
Settings → Apps → [App] → Audio Output: On/Off
This would solve a surprisingly common problem: I may deliberately be listening to Spotify, an audiobook or a podcast, then open another app which suddenly produces audio from an advertisement or autoplaying video. That audio may mix with, duck, or even interrupt what I actually chose to listen to.
As I understand the current architecture, apps use AVAudioSession to describe how their audio should interact with other audio. But much of that policy is therefore controlled by the application producing the unwanted audio, rather than by the device owner.
The simplest solution wouldn’t require a per-app mixer or complicated audio controls. Just one user-controlled permission:
Allow Audio Output: On / Off
When disabled, iOS would prevent that app from producing audible media output, while audio sessions belonging to other apps would continue normally.
Conceptually, this seems very similar to the existing Microphone permission:
Microphone: Can this app receive audio from my device?
Audio Output: Can this app produce audio on my device?
More advanced controls — per-app volume, permission to interrupt other audio, ducking policy, etc. — could potentially come later. But they aren’t necessary to solve the fundamental problem.
I’m curious from an AVAudioSession perspective:
Is there a technical reason why iOS could not enforce an OS-level per-app Audio Output permission in the same way it already enforces Microphone access?
And if there isn’t, would others find this useful?