Do you want to copy Music files to your IOS device to play on the go? Or do you want to stream music files to your device while you are on the same network as your MC computer? You can do either.
Copying files from MC isn't exactly elegant with an IOS device. It's rather manual. But you can do it.
Streaming is easy. Just buy JRemote and connect to your MC server. Then play to "this device" in JRemote. Music comes out of your IOS device.
Brian.