iOS
(previously iPhone
OS)
is a mobile operating system developed by Apple Inc. and distributed
exclusively for Apple hardware. It is the operating system that
powers many of the company's iDevices.
Originally
unveiled in 2007 for the iPhone, it has been extended to support
other Apple devices such as the iPod Touch (September 2007), iPad
(January 2010), iPad Mini (November 2012) and second-generation Apple
TV onward (September 2010). As of June 2014, Apple's App Store
contained more than 1.2 million iOS applications, 500,000 of which
were optimized for iPad. These apps have collectively been downloaded
more than 60 billion times. It had a 21% share of the smartphone
mobile operating system units shipped in the fourth quarter of 2012,
behind Google's Android. By the middle of 2012, there were 410
million devices activated. According to the special media event held
by Apple on September 12, 2012, 400 million devices had been
sold by June 2012.
The
user interface of iOS is based on the concept of direct manipulation,
using multi-touch gestures. Interface control elements consist of
sliders, switches, and buttons. Interaction with the OS includes
gestures such as swipe,
tap,
pinch,
and reverse
pinch,
all of which have specific definitions within the context of the iOS
operating system and its multi-touch interface. Internal
accelerometers are used by some applications to respond to shaking
the device (one common result is the undo command) or rotating it in
three dimensions (one common result is switching from portrait to
landscape mode).
iOS
shares with OS X some frameworks such as Core Foundation and
Foundation; however, its UI toolkit is Cocoa Touch rather than OS X's
Cocoa, so that it provides the UIKit framework rather than the AppKit
framework. It is therefore not compatible with OS X for applications.
Also while iOS also shares the Darwin foundation with OS X, Unix-like
shell access is not available for users and restricted for apps,
making iOS not fully Unix-compatible either.
Major
versions of iOS are released annually. The current release, iOS 7,
was released on September 18, 2013. In iOS, there are four
abstraction layers: the Core OS layer, the Core Services layer, the
Media layer, and the Cocoa Touch layer. The current version of the
operating system (iOS 7.1.2), dedicates 1–1.5 GB of the device's
flash memory for the system partition, using roughly 800 MB of that
partition (varying by model) for iOS itself. It runs on the iPhone 4
and later, iPad 2 and later, all models of the iPad Mini, and the
5th-generation iPod Touch.
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