How to change device Volume on iOS - not music volume

Question

I want to change the device volume on iOS (iphone).

I know that i can change the volume of music library with this lines below:

//implement at firs         


        

Answer 1

The app should not change device global settings and you should not do that. User can do that using standard iOS features. Instead, if you playing a sound/video, then use player's volume:

var player: AVPlayer!
...
player.volume = 0.5 // 50% level