Help sending a char to Arduino from an iPhone via hardware serial

liudr: OK cool. Then my step of checking connection is unnecessary. What did you change between non-working and working? Was it objective C or Arduino?

It was Objective-C code :-/ Still not sure why the app I created is not communicating with the Arduino ...probably because I wrote it (-.-)

Because you either needed to invert the serial line to talk to the micro, or use a MAXxxx device to convert the line voltage.