Audiobus? Think Big Plans
When gear, specifically MIDI gear, is developed for use with iOS, the developers have the option of simply creating it without their help or they can go to Apple and ask for their blessing. The second option usually gives the better results since the manufacturer can then say that their equipment is approved by Apple. I think we’ve all had our share of gear that was mean to be used with Apple products, yet failed horribly because there was very little research done before its development. With the way Apple likes to make their hardware you can see why it is important to communicate with them before you try something on your own.
With the software side there tends to be much more leniency. A developer can code a program without ever needing Apple support, so long as they know what they are doing. However, if you are building an app that digs deep into the Apple operating system, you will likely need their approval before real steps can be made. This is what Audiobus did in order to win the support of both Apple and the other clients who allowed their apps to be tooled for Audiobus. Apple has a core audio team specifically designed to work with audio implements.