iOS

File:Operating system iphone 5.PNG iOS 5.1.1 running on an iPhone 4S
Company / developer	Apple Inc.
Programmed in	C, C++, Objective-C
OS family	OS X, Unix
Working state	Current
Source model	Closed
Initial release	June 29, 2007
Latest stable release	iPhone (3GS and later) iPod Touch (3G and later) iPad (all models) 5.1.1 (Build 9B206)  (May 7, 2012; 50 days ago  (2012-05-07)) iPhone 4 GSM 5.1.1 (Build 9B208)  (May 25, 2012; 32 days ago  (2012-05-25)) [±]
Latest unstable release	none [±]
Available language(s)	34 languages[1][2]
Supported platforms	ARM (iPhone, iPod Touch, iPad, and 2nd gen. and higher Apple TV), Apple A4, Apple A5, Apple A5X
Kernel type	Hybrid (XNU)
Default user interface	Cocoa Touch (multi-touch, GUI)
License	Proprietary EULA except for open-source components
Official website	www.apple.com/ios

iOS (originally iPhone OS) is a mobile operating system developed and distributed by Apple Inc. Originally released in 2007 for the iPhone and iPod Touch, it has since been extended to support other Apple devices such as the iPad and Apple TV. Unlike Windows CE (Mobile and Phone) and Android, Apple does not license iOS for installation on non-Apple hardware. As of March 6, 2012 (2012 -03-06)^[update], Apple's App Store contained more than 550,000 iOS applications,^[3] which have collectively been downloaded more than 25 billion times. It had a 16% share of the smartphone operating system units sold in the last quarter of 2010, behind both Google's Android and Nokia's Symbian.^[4] In May 2010 in the United States, it accounted for 59% of mobile web data consumption (including use on both the iPod Touch and the iPad).^[5]

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. The response to user input is immediate and provides a fluid interface. 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 is derived from OS X, with which it shares the Darwin foundation, and is therefore a Unix operating system.

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 5.1.1) uses roughly 770 megabytes of the device's storage, varying for each model.^[6]

History[link]

The operating system was unveiled with the iPhone at the Macworld Conference & Expo, January 9, 2007, and released in June of that year (November in the United Kingdom).^[7] At first, Apple marketing literature did not specify a separate name for the operating system, stating simply that the "iPhone runs OS X".^[8] Initially, third-party applications were not supported. Steve Jobs argued that developers could build web applications that "would behave like native apps on the iPhone".^[9][10] 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".^[11] 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.^[12] 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.^[13]

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.^[14]

Version history[link]

Apple licensed the trademark for "iOS" from Cisco Systems (which owns IOS), the same company with which Apple had earlier settled a dispute over the "iPhone" trademark.^[15]

Apple released iOS 4 on June 21, 2010, three days before the iPhone 4,^[16] in an effort to reduce the strain on Apple's servers. iOS 4 was the first version of the OS to be a free upgrade on the iPod touch; Apple had charged $4.99 for earlier upgrades. Apple previously announced that iPad users with 3.x software would receive a free upgrade to the next major (4.x) release.^[17]

iOS 4.0.1 included a fix to the reception signal strength indicator(s). It was released on July 15, 2010, the day before Apple hosted a press conference to discuss its response to the widely publicized iPhone antenna issues. Apple also released iOS 3.2.1 for the iPad which tweaked the tablet's Wi-Fi connectivity, video playback, and copy-and-paste for PDF attachments, among other updates.

iOS 4.1 for the iPhone and iPod touch was released on September 8, 2010; the update fixed some bugs reported by users, improved battery life and added several new features:

• Game Center, which allows gamers to play multiplayer games online, upload high scores and unlock achievements (though Apple removed Game Center from the iPhone 3G because of reports of slow performance)
• The ability to toggle spell checking on and off
• HDR photography (iPhone 4 and 4S only)
• Ping, a social music network and discovery tool

iOS 4.1 also updated carrier settings which (at that time in the United States, AT&T 8.0 only). At the same time, TV show rentals became available on the iTunes US Store.

iOS 4.2 was never released but instead iOS 4.2.1 was released on November 22, 2010. It added iPad compatibility. Further on iOS 4.2.5 was released as a demo version for the CDMA version of the iPhone 4. This iPhone 4 variant was released for Verizon Wireless customers in the US on February 10, 2011, but pre-ordering was available for qualified Verizon Wireless Customers on February 3. The version released with the phone, 4.2.6, has some slight UI changes specifically for the CDMA version of the phone, including a "Personal Hotspot" switch in the Settings app, a service which has to be activated by the carrier in order for the feature to be usable. This became available for purchase from Verizon as a separate plan, as is currently possible on other smartphones.

iOS 4.3 was released to the public on March 9, 2011, two days before the iPad 2 was available in the United States. In addition to earlier features, the public release of iOS 4.3 included many new features such as a Nitro JavaScript engine in Safari, making Safari run up to twice as fast according to Apple.^[18] iTunes Home Sharing also received a major revision in iOS 4.3; it allows users to connect to their home Wi-Fi networks and stream content from iOS devices to speakers, TVs and other devices, or vice versa.^[18] Personal Hotspot for iPhone 4 is a new feature to GSM iPhones (previously released with the Verizon CDMA iPhone) that allows the user to create a Wi-Fi network with an iPhone 4 and provide Internet access for up to five other devices on Verizon Wireless, three on AT&T.^[19][20] In addition, the side button on the iPad is now customizable, with users able to use it either as a system sound mute or as a screen rotation lock.^[18] iOS 4.3 was not released for CDMA iPhones, which stayed on 4.2.x versions until they were upgraded to iOS 5 with the rest of the iOS line on October 12, 2011.

iOS 5.0 and its features were announced on June 6 at the WWDC 2011 keynote address. The update was released at 6 pm GMT on October 12, 2011. iOS 5 introduced the iCloud service and the Notification Center, as well as improvements to native apps such as Camera. The operating system also features new applications, such as the "Reminders" app and "Newsstand", a special home screen folder and App Store category that contains newspaper and magazine apps. "iMessage" is an application that allows iPod touch, iPhone, and iPad users to communicate, much like a chat service only used between these devices. The iMessage feature has been integrated into the "Messages" application on the iPhone. The iPod application on the iPhone and iPad has now been split into the Music and Video application, just as it had been on the iPod touch. On the iPhone 4S a virtual assistant named Siri was added. Siri allows users to talk to their iPhone 4S and perform various tasks, send messages, create alerts, and do internet searches. The new OS also features Twitter integration. All devices can now be setup without using a desktop or laptop computer. Almost all system apps were updated with new features or a redesigned interface. It also added updated security and bug fixes. According to Apple, the new OS has over 200 new features.^[21]

iOS 5.0.1 was released in the winter of 2011. This update Included a number of various bug fixes and a security update. The update also fixes battery problems with new devices and errors with the iCloud service. Also included were various other bug fixes and some new methods for developers.

iOS 5.1 was announced alongside the iPad and Apple TV (3rd generations) during a special press event at the Yerba Buena Center for the Arts in San Francisco on March 7, 2012. Not much of the event was dedicated to the new software release, and it was generally viewed as a minimally incremental release. Later that day, users of iOS devices were able to upgrade to the new operating system. New features include support for Siri in Japanese as well as the ability to delete photos from Photo Stream on an iOS device. The iPad also received a redesigned camera app. The over-the-air 3G download limit from the App Store was increased from 20 MB to 50 MB.

iOS 5.1.1 was released in the spring of 2012. This update included a number of various bug fixes and a security update.

Features[link]

Home screen[link]

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, applications, emails, contacts and similar files.

Folders[link]

With iOS 4 came the introduction of a simple folder system. When applications are in "jiggle mode", any two 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 and iPod touch and 20 on iPad. A title for the folder is automatically selected by the type of applications inside, but the name can also be edited by the user.

Notification Center[link]

In the iOS 5 update, the notifications feature was completely redesigned. Notifications now collate in a window which can be dragged down from the top of the screen. If a user touches a received notification, he/she will go to the application that sent the notification.

Included applications[link]

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.

All of the utilities, such as voice memos, clock, calculator, and compass are in one folder called "Utilities" in 4.0.^[22][23] 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).

The iPod touch retains the same applications that are present by default on the iPhone, with the exception of the Phone, Messages, Compass and Camera (before the 4th generation) apps. The "iPod" App previously present on the iPhone was split into two apps with iOS 5, Music and Videos, as it always has been on the iPod touch. The bottom row of applications is also used to delineate the iPod touch's main purposes: Music, Videos, Safari, and App Store (Dock Layout was changed in 3.1 Update). For the 4th Generation iPod touch, it includes FaceTime and Camera, and the dock layout had changed to Music, Mail, Safari, Video. As of iOS 5.0, "iMessage" will be available on all iOS devices running iOS 5. iMessage is effectively a version of the iPhone Messages app that sends free text or multimedia messages to other iOS devices (similar to BlackBerry Messenger).

The iPad comes with the same applications as the iPod touch excluding Stocks, Weather, Clock, Calculator, and the Nike + iPod app. Separate music and video apps are provided, as on the iPod touch, although (as on the iPhone) the music app is named "iPod". Although, that was changed in iOS 5 to "Music", to match the other devices in the family. Most of the default applications are completely rewritten to take advantage of the iPad's larger display. The default dock layout includes Safari, Mail, Photos and Music.

Multitasking[link]

Before iOS 4, multitasking was limited to a selection of the applications Apple included on the devices and an array of jailbroken modifications.^[24] Starting with iOS 4, on 3rd-generation and newer iOS devices, multitasking is supported through seven background APIs:^[25]

1. Background audio – application continues to run in the background as long as it is playing audio or video content^[26]
2. Voice over IP – application is suspended when a phone call is not in progress^[26]
3. Background location – application is notified of location changes^[26]
4. Push notifications
5. Local notifications – application schedules local notifications to be delivered at a predetermined time^[26]
6. Task completion – application asks the system for extra time to complete a given task^[26]
7. Fast app switching – application does not execute any code and may be removed from memory at any time^[26]

Switching applications[link]

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.

Game Center[link]

Game Center is an online multiplayer "social gaming network"^[27] released by Apple.^[28] 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.^[27]

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.^[27] 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.^[29] There is no support for the iPhone 3G and original iPhone. However, Game Center is unofficially available on the iPhone 3G via a hack.^[30]

Development[link]

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.

SDK[link]

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.^[31] 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.

As of April 2012^[update], 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, 2010, 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 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.

Since the release of Xcode 3.1, Xcode is the development environment for the iOS SDK. iPhone applications, like iOS and OS X, are written in Objective-C.^[32]

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). Alternately, 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.^[33]

Jailbreaking[link]

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.^[34] Apple has 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.^[35]

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.^[36] People now jailbreak for many different reasons, including pirating App Store applications, 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.

In 2010, the EFF successfully convinced the U.S. Copyright Office to reject Apple's claim that jailbreaking is in violation of the Digital Millennium Copyright Act and declare that iOS jailbreaking is legal in the United States.^[37]

Digital rights management[link]

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.^{[38][39][40][41]} Competitor Microsoft, via a PR spokesman, has also criticized Apple's control over its platform.^[42]

At issue are restrictions imposed by the design of iOS, namely 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.^[43][44] However, there are some outside of Apple who have voiced support for the iOS closed model. Facebook developer Joe Hewitt, who had previously protested against Apple's control over its hardware as a "horrible precedent", has subsequently argued the locked apps in the iPad are akin to web applications and provide added security.^[45]

Devices[link]

See also[link]

• Android
• Windows Phone
• List of iOS devices

References[link]

Further reading[link]

External links[link]

• Official website
• iOS Dev Center – on the Apple Developer Connection website
• iOS Reference Library – on the Apple Developer Connection website

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