iOS 6 running on an iPhone 5
|Company / developer||Apple Inc.|
|Programmed in||C, C++, Objective-C|
|OS family||OS X, UNIX|
|Source model||Closed source|
|Initial release||July 29, 2007|
|Latest stable release||
|Available language(s)||34 languages|
|Supported platforms||ARM (iPhone, iPod Touch, iPad, iPad Mini, and 2nd gen. and higher Apple TV), Apple A4, Apple A5, Apple A5X, Apple A6, Apple A6X|
|Kernel type||Hybrid (XNU)|
|Default user interface||Cocoa Touch (multi-touch, GUI)|
|License||Proprietary EULA except for open-source components|
iOS (previously iPhone OS) is a mobile operating system developed and distributed by Apple Inc. Originally released in 2007 for the iPhone and iPod Touch platforms, it has been extended to support other Apple devices such as the iPad and Apple TV. Unlike Microsoft's Windows Phone and Google's Android, Apple does not license iOS for installation on non-Apple hardware. As of September 12, 2012[update], Apple's App Store contained more than 700,000 iOS applications, which have collectively been downloaded more than 40 billion times. It had a 21% share of the smartphone mobile operating system units shipped in the fourth quarter of 2012, behind only Google's Android. In June 2012, it accounted for 65% of mobile web data consumption (including use on both the iPod Touch and the iPad). At the half of 2012, there were 410 million devices activated. According to the special media event held by Apple on September 12, 2012, 400 million devices have been sold through 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).
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 6.1.3) 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.
iOS currently runs on iPhone, iPad, iPod touch and Apple TV.
The operating system was unveiled with the iPhone at the Macworld Conference & Expo, January 9, 2007, and released in June of that year. At first, Apple marketing literature did not specify a separate name for the operating system, stating simply that the "iPhone runs OS X". Initially, third-party applications were not supported. Steve Jobs' reasoning was that developers could build web applications that "would behave like native apps on the iPhone". On October 17, 2007, Apple announced that a native Software Development Kit (SDK) was under development and that they planned to put it "in developers' hands in February". On March 6, 2008, Apple released the first beta, along with a new name for the operating system: "iPhone OS".
Apple had released the iPod touch, which had most of the non-phone capabilities of the iPhone. Apple also sold more than one million iPhones during the 2007 holiday season. On January 27, 2010, Apple announced the iPad, featuring a larger screen than the iPhone and iPod touch, and designed for web browsing, media consumption, and reading iBooks.
In June 2010, Apple rebranded iPhone OS as "iOS". The trademark "IOS" had been used by Cisco for over a decade for its operating system, IOS, used on its routers. To avoid any potential lawsuit, Apple licensed the "IOS" trademark from Cisco.
By late 2011, iOS accounted for 60% of the market share for smartphones and tablet computers. By the end of 2012, iOS accounted for 21% of the smartphone OS market and 43.6% of the tablet OS market.
Version history 
Apple provides major updates to the iOS operating system approximately once a year over iTunes and also, since iOS version 5.0, over the air. The latest major update is iOS 6, publicly announced on June 11, 2012 and released on September 12, 2012. Over 200 new features debut in iOS 6, including Apple's new Passbook service, Apple-sourced Maps, and full Facebook integration.
Home Screen 
|This section does not cite any references or sources. (June 2012)|
The home screen (rendered by and also known as "SpringBoard") displays application icons and a dock at the bottom of the screen where users can pin their most frequently used apps. The home screen appears whenever the user switches on the device or presses the "Home" button (a physical button on the device). The screen has a status bar across the top to display data, such as time, battery level, and signal strength. The rest of the screen is devoted to the current application. When a passcode is set and a user switches on the device, the Lock Screen is displayed.
Since iOS version 3.0, a Spotlight Search function has been available on the leftmost page of the home screen page allowing users to search through media (music, videos, podcasts, etc.), applications, e-mails, contacts, messages, reminders, calendar events, and similar files.
In iOS 3.2 or later and with a supported device, the user can set a picture as the background of the home screen. This feature is only available on third-generation devices or newer – iPhone 3GS or newer, iPod touch 3rd gen. or newer, and all iPad models.
With iOS 4 came the introduction of a simple folder system. When applications are in "jiggle mode", any two (with the exception of Newsstand in iOS 5 and later, which acts like a folder) can be dragged on top of each other to create a folder, and from then on, more apps can be added to the folder using the same procedure, up to 12 on iPhone 4S and earlier and iPod touch, 16 on iPhone 5, and 20 on iPad. A title for the folder is automatically selected by the category of applications inside, but the name can also be edited by the user.
Notification Center 
In the iOS 5 update, the notifications feature was completely redesigned. Notifications collate in a window which can be dragged down from the top of the screen. If a user touches a received notification, the application that sent the notification will be opened.
Included applications 
The iOS home screen contains these default "apps". Some of these applications are hidden by default and accessed by the user through the Settings app or another method—for instance, Nike+iPod is activated through the Settings app. Many of these apps, such as Safari, the App Store, and YouTube, can also be disabled in the Restrictions section of the Settings app.
|Series||iPhone||iPod Touch||iPad||iPad Mini|
|Music||Portable media player||1.0
|Home screen backgrounds||N/A||4.0||N/A||4.0||3.2|
|Series||iPhone||iPod Touch||iPad||iPad Mini|
|iMessage instant messaging||N/A||5.0||N/A||5.0||6.0||5.0||5.1||6.0||6.0|
|YouTube||YouTube video streamer (no longer integrated as of iOS 6)||N/A||N/A||N/A||N/A|
|Crop, red eye fix, auto enhance and photo rotate||N/A||5.0||N/A||5.0||5.0|
|Crop, red eye fix, auto enhance and photo rotate||5.0||5.0||5.0|
|Take still photos while recording video||N/A||N/A|
|FaceTime||Video calling over Wi-Fi||N/A||4.0||5.0||N/A||4.1||4.3||5.1||6.0||6.0|
|Video calling over 3G/LTE||N/A||6.0||N/A||N/A||6.0
(Wi-Fi + Cellular)
(Wi-Fi + Cellular)
(Wi-Fi + Cellular)
|Photo Booth||A camera application with added special effects||N/A||4.3||5.1||6.0||6.0|
|Stocks||Stocks provided by Yahoo! Finance||1.0||2.0||3.0||4.0||5.0||6.0||1.1.3||2.1.1||3.1.1||4.1||6.0||N/A||N/A|
|Stocks Widget for Notification Center||N/A||5.0||N/A||5.0|
|Weather||Weather provided by Yahoo! Weather||1.0||2.0||3.0||4.0||1.1.3||2.1.1||3.1.1||4.1|
|Weather Widget for Notification Center||N/A||5.0||N/A||5.0|
|Notes||A simple note-taking program||1.0||2.0||3.0||4.0||1.1.3||2.1.1||3.1.1||4.1||3.2||4.3||5.1||6.0||6.0|
|Maps||Google Maps (until 5.1.1)||N/A||N/A||N/A||N/A|
|Google Street View (until 5.1.1)|
(Wi-Fi + 3G)
(Wi-Fi + 3G)
(Wi-Fi + Cellular)
(Wi-Fi + Cellular)
(Wi-Fi + Cellular)
|Apple-sourced maps (6.0 onwards)||N/A||6.0||N/A||6.0||6.0||N/A||6.0||6.0|
|Turn-by-turn navigation using Apple-sourced maps||N/A||6.0||N/A|
|Newsstand||A newspaper and magazine store||N/A||5.0||5.0||5.0||N/A||5.0||5.0||5.1||6.0||6.0|
|Reminders||A to-do list application|
(Wi-Fi + Cellular)
(Wi-Fi + Cellular)
|Voice Memos||Voice recorder||3.0||3.0||4.0||3.0||3.1.1||4.1||6.0||N/A||N/A|
|Scientific calculator (triggered by rotating to landscape)||2.0||2.0|
|Clock||World clock, stopwatch, alarm clock and timer||1.0||1.1||N/A||6.0||6.0|
|iTunes||Access to the iTunes Music Store and iTunes Podcast Directory||1.1|
|App Store||To buy iOS apps||2.0||2.0|
|Nike + iPod||Records the distance and pace of a walk or run; can connect to Nike + iPod sensor (turned off by default – can be enabled in Settings)||N/A||2.1.1||3.1.1||4.1||6.0|
|Game Center||Play multiplayer games with other users, track in-game achievements, view leaderboards.||4.1||4.1||4.2.1||4.3||5.1||6.0||6.0|
|Voice Control||Simple voice control (disabling Siri may be necessary)||3.0||4.0||N/A||3.1.1||4.1||N/A||N/A|
|Siri||A personal voice assistant||N/A||N/A||N/A||6.0||6.0||6.0|
|Passbook||A virtual wallet application for passes, tickets, coupons and loyalty cards||N/A||6.0||N/A||6.0||N/A||N/A|
On the iPhone and iPod Touch, utilities, such as voice memos, contacts, calculator, and compass are in one folder called "Utilities" in iOS 4 and above. Many of the included applications are designed to share data (e.g., a phone number can be selected from an email and saved as a contact or dialed for a phone call).
"iMessage" is available on all iOS devices running iOS 5 or above. iMessage is effectively a version of the Messages app that sends free text or multimedia messages to other iOS devices (similar to BlackBerry Messenger).
The dock layout for the iPhone is Phone, Mail, Safari, Music. As of iOS 5, the iPod app previously present on the iPhone was split into two apps, Music and Videos, as it always has been on the iPod Touch. The iPod Touch retains the same applications that are present by default on the iPhone, with the exception of the Phone and Compass (and also previously, Messages before iOS 5 and Camera before the 4th generation iPod Touch ) apps. The bottom row of applications is also used to delineate the iPod Touch's main purposes: originally Music, Videos, Photos, and iTunes. For the iOS 3.0 update, the layout was changed to Music, Videos, Safari, and App Store. For the fourth generation iPod Touch, it includes FaceTime and Camera, and the dock layout had changed to Music, Mail, Safari, Videos. The new fifth generation iPod Touch had its dock layout changed again to Messages, Mail, Safari, Music, similar to the iPhone.
The iPad and iPad Mini come with the same applications as the iPod Touch, excluding Stocks, Weather, Calculator, and the Nike + iPod app (and also previously, Clock before iOS 6). Separate music and video apps are provided, as on the iPod Touch, although (as on the iPhone) the music app was named "iPod" up until iOS 5, when it was changed to "Music". Most of the default applications, such as Safari and Mail, are completely rewritten to take advantage of the iPad's and iPad Mini's larger displays. The original dock layout included Safari, Mail, Photos, and Music. As of iOS 6, the default layout is Safari, Mail, Videos, Music.
Before iOS 4, multitasking was limited to a selection of the applications Apple included on the device. Users could, however "jailbreak" their device in order to unofficially multitask. Starting with iOS 4, on 3rd-generation and newer iOS devices, multitasking is supported through seven background APIs:
- Background audio – application continues to run in the background as long as it is playing audio or video content
- Voice over IP – application is suspended when a phone call is not in progress
- Background location – application is notified of location changes
- Push notifications
- Local notifications – application schedules local notifications to be delivered at a predetermined time
- Task completion – application asks the system for extra time to complete a given task
- Fast app switching – application does not execute any code and may be removed from memory at any time
In iOS 5, three new background APIs were introduced:
- Newsstand – application can download content in the background to be ready for the user
- External Accessory – application communicates with an external accessory and shares data at regular intervals
- Bluetooth Accessory – application communicates with a bluetooth accessory and shares data at regular intervals
Switching applications 
In iOS 4.0 or later, double-clicking the home button activates the application switcher. A scrollable dock-like interface appears from the bottom, moving the contents of the screen up. Choosing an icon switches to an application. To the far left are icons which function as music controls, a rotation lock, and on iOS 4.2 and above, a volume controller. Holding the icons briefly makes them "jiggle" (similarly to the homescreen) and allows the user to force quit the applications by simply tapping the red minus circle that appears at the corner of the app's icon.
Siri is an intelligent personal assistant and knowledge navigator which works as an application on supported devices. The service, directed by the user's spoken commands, can do a variety of different tasks, such as call or text someone, open an app, search the web, lookup sports information, find directions or locations, and answer general knowledge questions (e.g. "How many cups are in a gallon?"). Siri is currently only available on iPhone 4S, iPhone 5, 5th generation iPod touch, iPad Mini, 3rd generation iPad and 4th generation iPad.
Game Center 
Game Center is an online multiplayer "social gaming network" released by Apple. It allows users to "invite friends to play a game, start a multiplayer game through matchmaking, track their achievements, and compare their high scores on a leader board." iOS 5 and above adds support for profile photos.
Game Center was announced during an iOS 4 preview event hosted by Apple on April 8, 2010. A preview was released to registered Apple developers in August. It was released on September 8, 2010 with iOS 4.1 on iPhone 4, iPhone 3GS, and iPod touch 2nd generation through 4th generation. Game Center made its public debut on the iPad with iOS 4.2.1. There is no support for the iPhone 3G and original iPhone. However, Game Center is unofficially available on the iPhone 3G via a hack.
The applications must be written and compiled specifically for iOS and the ARM architecture. The Safari web browser supports web applications as with other web browsers. Authorized third-party native applications are available for devices running iOS 2.0 and later through Apple's App Store.
On October 17, 2007, in an open letter posted to Apple's "Hot News" weblog, Steve Jobs announced that a software development kit (SDK) would be made available to third-party developers in February 2008. The SDK was released on March 6, 2008, and allows developers to make applications for the iPhone and iPod touch, as well as test them in an "iPhone simulator". However, loading an application onto the devices is only possible after paying an iPhone Developer Program fee.
The fees to join the respective programs for iOS and OS X were stated at $99.00 per developers license. This $99.00 fee must be paid annually in order for the developer to maintain their license. As of July 20, 2011, Apple released Xcode on its Mac App Store free to download for all OS X Lion users. Users can create and develop iOS Applications using a free copy of Xcode, however they cannot test their applications on a physical iOS device, post them to the App store or make profit from their applications without first paying the $99.00 iPhone Developer or Mac Developer Program fee.
Developers are able to set any price above a set minimum for their applications to be distributed through the App Store, of which Apple will take 30% of the revenue (the other 70% goes to the developer). Alternatively, they may opt to release the application for free and need not pay any costs to release or distribute the application except for the membership fee.
Ever since its initial release, iOS has been subject to a variety of different hacks centered around adding functionality not allowed by Apple. Prior to the 2008 debut of the native iOS App Store, the primary motive for jailbreaking was to install third-party native applications, which was not allowed by Apple at the time. Apple claimed that it will not release iOS software updates designed specifically to break these tools (other than applications that perform SIM unlocking); however, with each subsequent iOS update, previously un-patched jailbreak exploits are usually patched.
Ever since the arrival of Apple's native iOS App Store, and—along with it—third-party applications, the general motives for jailbreaking have changed. People jailbreak for many different reasons, including gaining filesystem access, installing custom device themes, and modifying the device SpringBoard. On some devices, jailbreaking also makes it possible to install alternative operating systems, such as Android and the Linux kernel. Primarily, users jailbreak their devices because of the limitations of iOS. It should be noted that depending on the method used, the effects of jailbreaking may be permanent, or can be restored to the original state.
In 2010, the Electronic Frontier Foundation (EFF) successfully convinced the U.S. Copyright Office to allow an exemption to the general prohibition on circumvention of copyright protection systems under the Digital Millennium Copyright Act (DMCA). The exemption allows jailbreaking of iPhones for the sole purpose of allowing legally obtained applications to be added to the iPhone. The exemption does not affect the contractual relations between Apple and an iPhone owner, for example, jailbreaking voiding the iPhone warranty; however, it is solely based on Apple's discretion on whether they will fix jailbroken devices in the event that they need to be repaired. At the same time, the Copyright Office exempted unlocking an iPhone from DMCA's anticircumvention prohibitions. Unlocking an iPhone allows the iPhone to be used with any wireless carrier using the same GSM or CDMA technology for which the particular phone model was designed to operate.
Initially many wireless carriers did not allow iPhone owners to unlock an iPhone for use with other carriers. AT&T Mobility allows iPhone owners who have satisfied the requirements of their contract to unlock their iPhone. Instructions to unlock the device are available from Apple, but it is ultimately the sole discretion of the carrier to authorize the device to be unlocked. This allows the use of a carrier sourced iPhone on other networks. However, because T-Mobile primarily uses a different band than AT&T for its 3G data signals, the iPhone will only work at 3G speeds on the T-Mobile 1900mhz network. There are programs to break these restrictions, but are not supported by Apple and most often not a permanent unlock, known as soft-unlock.
Digital rights management 
The closed and proprietary nature of iOS has garnered criticism, particularly by digital rights advocates such as the Electronic Frontier Foundation, computer engineer and activist Brewster Kahle, Internet-law specialist Jonathan Zittrain, and the Free Software Foundation who protested the iPad's introductory event and have targeted the iPad with their "Defective by Design" campaign. Competitor Microsoft, via a PR spokesman, criticized Apple's control over its platform.
At issue are restrictions imposed by the design of iOS, namely digital rights management (DRM) intended to lock purchased media to Apple's platform, the development model (requiring a yearly subscription to distribute apps developed for the iOS), the centralized approval process for apps, as well as Apple's general control and lockdown of the platform itself. Particularly at issue is the ability for Apple to remotely disable or delete apps at will.
Some in the tech community have expressed concern that the locked-down iOS represents a growing trend in Apple's approach to computing, particularly Apple's shift away from machines that hobbyists can "tinker with" and note the potential for such restrictions to stifle software innovation. Former Facebook developer Joe Hewitt protested against Apple's control over its hardware as a "horrible precedent" but praised iOS's sandboxing of apps.
See also 
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Further reading 
- Hillegass, Aaron; Conway, Jon (March 22, 2012). iOS Programming: The Big Nerd Ranch Guide (3rd ed.). Pearson. p. 590. ISBN 978-0-321-82152-2.
- Turner, Kirby (December 19, 2011). Learning iPad Programming: A Hands-on Guide to Building iPad Apps with iOS 5 (1st ed.). Pearson. p. 816. ISBN 978-0-321-75040-2.
- Mark, Dave; LaMarche, Jeff (July 21, 2009). Beginning iPhone 3 Development: Exploring the iPhone SDK (1st ed.). Apress. p. 584. ISBN 1-4302-2459-2.
- Mark, Dave; LaMarche, Jeff (December 29, 2009). More iPhone 3 Development: Tackling iPhone SDK 3 (1st ed.). Apress. p. 552. ISBN 1-4302-2505-X.
- Official website
- Developers News
- iOS Dev Center – on the Apple Developer Connection website
- iOS Reference Library – on the Apple Developer Connection website