I use an app in my iPhone. I changed the head unit in my plus 4 this year for a Sony with remote control and USB. The USB keeps the phone charged and the directions come over the speakers when using navigation, quietening anything you might be listening to.
I used it last weekend for the AGM at the factory, it was superb.
Cheers
Mike

Mike Hughes
1969 4/4 competition (ST170)
2008 +4
1962 Vitesse 6 Formosa
1959 Peerless GT2