If you have the iPod option, it would have come with a "Y" cable. The "Y" cable MUST plug into BOTH the USB and the AUX port in the center console. Plug the iPod (or the iPhone) into the "Y" cable and you should see your iPhone show up in the navigation screen under CD/Multimedia.
If you don't see it, I would suspect that you have a bad "Y" cable (as I did) and the dealer will swap it out for a new one.
2013 335i xDrive – 6-speed, AW, M Sport Line, Cold Weather, Dymanic Handling, Premium, Technology, 403M, Black Grills, Carbon Caps, Performance Exhaust