I don't expect to be able to SET the user-controlled system volume, but being able to read it would be helpful.
Example: I'm adding alarm clock function to my Playtime clocks app. When someone sets an alarm, I'd like to be able to display a warning if the volume is set below 25%, say. (I can already detect attached headphones for the same reason.)
Could be useful for games too: if audio is absolutely vital, a game might choose to warn people if the sound is muted/low.
(My fallback solution: play a sound as the alarm is set—at least it's a chance for the user to notice on their own if they can't hear the expected feedback.)
I have another use case for this function I’m writing a (admittedly, very shoddy, partial) emulator, and I want to do my sound in a blocking manner for the purposes of realism, but when the system volume is set to 0 the game just feels stuttery (and the menu screen spends 30s doing nothing!) without purpose - so I’d love to be able to disable the sound emulation entirely if the system volume is 0.
I have a workaround for the title screen already (a toggle for the sounds in the PD menu ), so not looking for advice. Just trying to show that there are other uses for it (or getSystemVolumeMuted() → true|false)