create hardware for iphone to connect with external device. arduino?

Question

hi i need to create a simple connector. I think i may need to create an arduino board that will take data from the application and then transmit them to an external device.

Answer 1

The other answers are good, but there is one final alternative - you can use phase-shift keying (or similar methods) to connect a device to the iPhone via the headphone/microphone socket and communicate with the device via audio tones.

Someone has done a library for this already, however I can't currently seem to find the link. They did claim they'd got apps into the appstore that use this method.

Update

Found a good collection of links about this here:

http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?num=1274970878