I\'m currently running the followin in Terminal to send a command over USB serial.
/Users/drummerboyx/Library/Scripts/arduino-serial -b 9600 -p /dev/tty.usbs
ORSSerialPort is a newer, easier to use alternative to AMSerialPort.
Using ORSSerialPort to open a port and send data can be as simple as this:
ORSSerialPort *serialPort = [ORSSerialPort serialPortWithPath:@"/dev/cu.KeySerial1"];
serialPort.baudRate = [NSNumber numberWithInteger:4800];
[serialPort open];
[serialPort sendData:someData]; // someData is an NSData object
[serialPort close];