Chapter 1. Keeping the System Up-to-Date
This Is the iPhone 4S
Apple introduced the successor of the successful iPhone 4 in October 2011. The two devices look as similar as their names sound: the iPhone 4 is followed by the iPhone 4S. The very good stuff is still there; for instance, the iPhone 4S also has the high-resolution 3.5-inch Retina display (960×640 pixels) with a contrast of 800:1 and a maximum brightness of 500 candela per square meter. The optically excellent glass back is also still there. But even if both devices look very similar, some major changes have happened on the inside.