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
Find My iPhone Find My iPhone allows users to locate their iOS devices using either the iOS app or icloud.com on a computer. In addition to locating a device, the service provides three key features: The update with iOS 6 added the ability to check the device's battery level. Since the release of iOS 7 users have complained about the link between GPS, WiFi, and the App itself. Some handset owners have noted the App enables and disables itself when passing between cellular protocol bandwidths. , the service is supported on iPhone, iPad, iPod Touch, and Mac computers running OS X 10.7.5 "Lion"