What you have looks right. Add it to the methods argument of your delegate, and also add the right protocol to your delegate class. MCNearbyServiceAdvertiserDelegate
You are requires to call the handler block with a boolean accept argument, and a MCSession initalized from the peer. StackOverflow gives me:accept=true session = ObjCClass('MCSession').alloc().initWithPeer(peerID) session.delegate = YOURSERVICEADVERTISERDELEGATE ObjCInstance(handler).invoke(accept, session)
Disclaimer... I don't have anything to test out, you need o find a good end to end example written in ObjC or swift to port over... some of these frameworks are tricky to work with just from the docs alone.