Specifically i'm processing ARFrames - the first class is only interested in handling ARState changes, and the second is dispatching ARFrames for vision work. The ARstate monitor class only needs to act at a much lower frequency than the one doing vision processing. Since you can't really tune how often you sample the ARFrames, I have 2 very different handling loops. Only being able to register a single ARDelegate, means that whoever gets it first, then needs to relay the frame on to anyone else who is listening to it. I implemented this as a chain of command for now, but like I said, I'm not sure what the common pattern for doing this would be.