updated 11:05 am EDT, Tue April 13, 2010
Enables secondary interface
One of the lesser-known additions to iPhone 4.0, "iPod Out," may be intended in part to support integration with vehicles, a source suggests. When a handheld is connected to a device supporting the iPod Accessory Protocol, iPod Out will allegedly bring up a special interface (seen below) to be fed to a secondary display, with a simplified menu system resembling the one on the iPod classic and nano. Evidence for a connection to cars is said to come from two strings in iPod Out code, "IAPSimpleRemoteCarButtonNotification" and "IAPSimpleRemoteCarButtonTypeKey."
iPhones and iPods could thus become dumb remotes, possibly meant to dock with a car kit that makes it easier to control audio playback in a moving vehicle. Such a kit could include its own screen, the source proposes, and/or physical buttons to be used for cycling through selections. The person also observes that iPod Out may include hands-free calling support, thought to be implied by another code string, "kCTCallStatusChangeNotification."