Another iPhone AUX question

[Meir]

at some point i had the same thought myself.
i ended up installing a pioneer double DIN appradio, but these are the cables you will need to complete what you want.

https://www.amazon.com/AOAIS7505-Playback-Charging-Lightning-Connector/dp/B00KG5S7CC/ref=sr_1_3?ie=UTF8&qid=1495931037&sr=8-3&keywords=lightning+cable+to+rca

https://www.amazon.com/Porsche-1999-2002-Traffic-CDR-220-Coaster/dp/B012IVK5W6/ref=sr_1_fkmr1_4?ie=UTF8&qid=1495931143&sr=8-4-fkmr1&keywords=becker+connector+to+rca

https://www.amazon.com/Manhattan-inches-Stereo-Splitter-3-5mm-Adapter/dp/B0009JFF7A/ref=sr_1_1?ie=UTF8&qid=1495931503&sr=8-1&keywords=3.5+mm+female+to+rca+female+adapter

as mentioned, i never ended up using these cables, so i cannot testify how well it works.
you might also find it cheaper from other sources then amazon.