first project q's

alright so my new project is to control 10 relays (8 valves momentary & 2 compressors on/off) with the arduino via a C based app. I am new to mac about 2weeks and i have never wrote C to interact with a gui so im battling that demon now. I would like to implement this into an objective-c app later, can i code it simply objective-c?

Within my searching i have found the way to physically connect the relay and i think im good there

However I am having a hell of a time understanding the todbot write up posted in the playground, i can honestly say my contacts fell out twice due to lack of moisture...

Basically all I have gotten from the arduino-serial app is that the serial must be initialized before data can be sent/received but how that actually works isn't exactly self explanatory

Does the PC/Mac C app already exist? If not, consider looking at what already exists. Like Processing or Gobetweeno or Firmata.

the app is writen in objective-c that i would like to implement my code into. it would be best to write it in objective-c but i didnt find anything on communicating with the arduino with that. the sketch-up i dont see being a problem since it will be in C and wait for data from the pc

i didnt find anything on communicating with the arduino with that.

One option is to use run the ser-proxy tool, which communicates over the virtual serial port, and provides a TCP port for your application to connect to.