We’ve had very few car radios from scratch here at Hackaday, but we have had more than one bluetooth upgrade or addition of a line-in port. Thanks [Darkspr1te] for the story.

The $22 kit includes an Arduino-BLE board and 6-pin header that should be fairly broadly applicable for building Arduino-based hardware that can communicate with iOS devices.

Thanks to the LightBlue Bean+, however, one of those roadblocks has been torn down. The Bean+ is basically an Arduino board that can be programmed via Bluetooth LE.