Change OS X system volume programmatically

Question

How can I change the volume programmatically from Objective-C?

I found this question, Controlling OS X volume in Snow Leopard which suggests to do:

Answer 1

You could run a bash script that will change the master volume. This prevents setting the audio first to one side:

Muted:

execlp("osascript", "osascript", "-e", "set volume output muted true", NULL);

Change volume (scale 0-10):

    execlp("osascript", "osascript", "-e", "set volume 5", NULL);