You cannot change the volume programmatically, and that's a deliberate design choice. Imagine an app that constantly sets the volume to the highest level, that would not only be annoying but could even damage your ears if you're wearing in-ear headphones.
You should show an MPVolumeView to the user so he can change the volume himself. You can walk its subview hierarchy and search for the UISlider
and adjust its appearance like with any normal UISlider. This way you can adapt the MPVolumeView
to your app design.
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…