Question: Is there an **easy** way to make an iPhone application communicate with a Mac app? By communicate, I mean able to control certain things within the mac application, like control a character on the monitor

Answer: 
`NSNetService` and `NSNetServiceBrowser` are the Cocoa classes for broadcasting and connecting to Bonjour services. I'd recommend starting with those.
Networking isn't easy!

The above answer by Dave is great if you can make the assumption that your phone and app/computer will be on the same network (behind router, firewall, etc). Otherwise, you'll need an external host (at a FQDN (URL) that both the phone and PC can reach) to manage the communication between the 2. At that point, you are making a web-based communications layer :(