IPhone 4S announced iPhone 5s and iPhone 5c. This was unusual for Apple as an upper case 'S' had been used since the introduction of the iPhone 3GS in 2009. On September 9, 2014, the iPhone 4S was officially discontinued following the reveal of the iPhone 6 and the iPhone 6 Plus. However, 4S production did continue for developing markets until February 17, 2016. On June 13, 2016, following the release of iOS 10, Apple dropped support on the iPhone 4S, making iOS 9.3.5 the last version available for the device. The runs iOS, Apple's mobile operating system. The user interface of
IPhone to develop the iPhone's hardware and software in-house and even paid Apple a fraction of its monthly service revenue (until the iPhone 3G), in exchange for four years of exclusive US sales, until 2011. Jobs unveiled the iPhone to the public on January 9, 2007, at the Macworld 2007 convention at the Moscone Center in San Francisco. The two initial models, a 4 GB model priced at US$499 and an 8 GB model at US$599 (both requiring a two-year contract), went on sale in the United States on June 29, 2007, at 6:00 pm local time, while hundreds of customers