For the case where the client simply wants to know whether the user changes
their volume, without having to implement and manage the KVO
Note: This retains the same limitation as that method, where pressing up
while already at the max volume (or down while at 0) will not trigger a callback
For the case where the client simply wants to know whether the user changes their volume, without having to implement and manage the KVO
Note: This retains the same limitation as that method, where pressing up while already at the max volume (or down while at 0) will not trigger a callback