IPhone 4 models. In fall 2010, pentalobe screws started to replace the Philips screws used in post-repair units in the US and in production units in Japan. The iPhone 4 shipped with iOS 4, which was the newest version of Apple's iOS mobile operating system at the time. iOS 4 introduced a multitasking system, allowing apps to remain "suspended" in memory, perform certain operations in the background, and allowing users to switch between apps using an on-screen menu. It also introduced FaceTime, which allows users to perform video calls between other iPhone, iPad, iPod Touch, and OS X users. The iPhone 4
VoiceOver iPod Shuffle VoiceOver is intended to be used by everyone, disabled or not. A few months later, with the release of the iPhone 3GS, VoiceOver was added to iOS. When the iPod Touch was upgraded to match the hardware of the iPhone 3GS (in iPod touch's third generation), it also gained VoiceOver capability. The iPad, since its introduction, has also had VoiceOver capability. VoiceOver on iOS interacts with the user by using various "gestures," different motions one makes with one or more fingers on the display. Many gestures are location-sensitive—for example, sliding one's finger around the screen will reveal the