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 OS 2 available to the iPhone and iPod Touch. Prior to the public release of iPhone OS 2.0, Apple held a keynote event to announce the iPhone OS Software Development Kit ("SDK") to developers. The most notable feature of iPhone OS 2 was the App Store. Before this feature was introduced, the only way to install custom applications on the device was via jailbreaking, which is strongly discouraged and unsupported by Apple. There were 500 applications available for download at the launch of the App Store, though this amount has grown dramatically since then. Now, the App Store has more than 2