Xcode，Core Audio：如何将音频从lineout路由到应用程序？

I need to make a Mac app that grabs the audio going to the lineout and renders it into memory. Is it possible to do this with core audio and if so is it at a high enough level to do this simply or do I need to do like soundflower and create a virtual sound device. Do you know any reference where I can get do this myself.I need to make a Mac app that grabs the audio g