IPhone 3GS was designed by Apple and launched after the iPhone 3G.
The iPhone 4S was announced on October 4, 2011, and introduced the Siri virtual assistant, a dual-core A5 processor, and an 8 megapixel camera with 1080p video recording functionality
The iPhone 4 was announced on June 7, 2010, at WWDC 2010, and introduced a redesigned body incorporating a stainless steel frame and a rear glass panel

