I bought the following cable on Amazon:
1) HDMI plugs in the dash HDMI port (connected to the Axerra)
2) Plug in the USB end to a power source
3) Plug the lightning connector into the iPhone.
Tap the Axerra screen at various prompts.
It works great, I just keep the iPhone in landscape mode, so the image fills the screen. I like it for following directions in the city without having to look at the phone. Axerra is more at eye level.
When you shut off the ignition, you have to disconnect everything and start over.