[Deprecated] Swift and Current Limitations of Audio Unit Implementations June 16, 2014 UPDATE (07/31/2014): Apple has since modified pointer usage, which might allow for the use of user-provided callbacks in CoreAudio. I have been up to my neck in dissertation work, so I have not been able to test this. Good luck! Swift currently (June 16, 2014) is less capable than Objective-C for real-time audio