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 3GS scheme from black on white to white on black, while Text Zoom allows users to zoom into a text on the screen. The iPhone 3GS retains the design of the 3G, with a glossy plastic back with tapered edges and metal buttons. The 3GS has reflective silver text on the reverse side which matches the silver Apple logo, replacing the 3G's grey text. Unlike its predecessor, the iPhone 3GS was available in white and black for 16 GB and 32 GB, although the 8 GB model was only available in black. Reviews of the iPhone 3GS have been generally mixed