iOS

iOS (formerly iPhone OS) is a created and developed by exclusively for . It is the operating system that presently powers many of the company's mobile devices, including the , and ; it also powered the prior to the introduction of in 2019. It is the second most popular mobile operating system globally after .

Originally unveiled in 2007 for the , iOS has been extended to support other Apple devices such as the (September 2007) and the (January 2010). As of March 2018, Apple's contains more than 2.1 million iOS applications, 1 million of which are native for iPads. have collectively been downloaded more than 130 billion times.

The iOS is based upon , using 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 are used by some applications to respond to shaking the device (one common result is the command) or rotating it in (one common result is switching between portrait and landscape mode). Apple has been significantly praised for incorporating thorough functions into iOS, enabling users with vision and hearing disabilities to properly use its products.

Major versions of iOS are released annually. On all recent iOS devices, iOS regularly checks on the availability of an update, and if one is available, will prompt the user to permit its automatic installation. The current version, was released to the public on 19 September 2019, introducing user interface tweaks and a dark mode, along with features such as a redesigned Reminders app, a swipe keyboard, and an enhanced Photos app. iOS 13 does not support devices with less than 2 GB of RAM, including the , , and the , which still make up over 10% of all iOS devices. and as the variant is now called .

Original iOS logo, used until 2013 (left) and logo used 2013–17 (right)

In 2005, when began planning the , he had a choice to either "shrink the Mac, which would be an epic feat of engineering, or enlarge the iPod". Jobs favored the former approach but pitted the and teams, led by and , respectively, against each other in an internal competition, with Forstall winning by creating the iPhone OS. The decision enabled the success of the iPhone as a platform for third-party developers: using a well-known desktop operating system as its basis allowed the many third-party Mac developers to write software for the iPhone with minimal retraining. Forstall was also responsible for creating a for programmers to build iPhone apps, as well as an within .

The operating system was unveiled with the iPhone at the on January 9, 2007, and released in June of that year. Initially, third-party native applications were not supported. Jobs' reasoning was that developers could build through that "would behave like native apps on the iPhone". In October 2007, Apple announced that a native was under development and that they planned to put it "in developers' hands in February".[24]

The was opened on July 10, 2008 with an initial 500 applications available. 15,000 in January 2009, 100,000 in November 2009, 250,000 in August 2010, 650,000 in July 2012, and 2.2 million in January 2017. As of March 2016, 1 million apps are natively compatible with the tablet computer. App intelligence firm Sensor Tower has estimated that the App Store will reach 5 million apps by the year 2020.[42]

In September 2007, Apple announced the , a redesigned based on the iPhone form factor., featuring a larger screen than the iPhone and iPod Touch, and designed for web browsing, media consumption, and reading.[44]

In June 2010, Apple rebranded iPhone OS as "iOS". The trademark "IOS" had been used by for over a decade for its operating system, , used on its routers. To avoid any potential lawsuit, Apple licensed the "IOS" trademark from Cisco.[45]

In October 2016, Apple opened its first iOS Developer Academy in inside 's new campus.

Software updates

Apple provides major updates to the iOS operating system annually via and also, for iOS 5 and later, ., released on September 19, 2019. It is available for and later, and the seventh-generation . at its annual It was released on September 24, 2019. iPadOS is available on and later, fifth-generation and later, and later and all versions of the .[52]

Originally, iPod Touch users had to pay for system software updates. This was due to accounting rules making the device not a "subscription device" like iPhone or Apple TV, and significant enhancements to the device required payments. The requirement to pay to upgrade caused iPod Touch owners to stay away from updates.[57]

Home screen

The home screen, rendered by , displays icons and a dock at the bottom where users can pin their most frequently used apps. The home screen appears whenever the user unlocks the device or presses the physical "Home" button while in another app., but can now be changed out-of-the-box. 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 passcode must be entered at the Lock Screen before access to the Home screen is granted.[59]

In iPhone OS 3, was introduced, allowing users to search media, apps, emails, contacts, messages, reminders, calendar events, and similar content. In iOS 7 and later, Spotlight is accessed by pulling down anywhere on the home screen (except for the top and bottom edges that open Notification Center and Control Center). In iOS 9, there are two ways to access Spotlight. As with iOS 7 and 8, pulling down on any homescreen will show Spotlight. However, it can also be accessed as it was in iOS 3 – 6. This endows Spotlight with Siri suggestions, which include app suggestions, contact suggestions and news.

Since iOS 3.2, users are able to set a background image for the Home screen. This feature is only available on third-generation devices—, third-generation (iOS 4.0 or newer), and all iPad models (since iOS 3.2)—or newer.

Researchers found that users organize icons on their homescreens based on usage frequency and relatedness of the applications, as well as for reasons of usability and aesthetics.[64]

System font

iOS originally used as the system font. Apple switched to exclusively for the and its , and retained Helvetica as the system font for older iPhone devices on iOS 4., an Apple-designed font aimed at maximum legibility and font consistency across its product lineup.

Folders

iOS 4 introduced folders, which can be created by dragging an application on top of another, and from then on, more items can be added to the folder using the same procedure. A title for the folder is automatically selected by the category of applications inside, but the name can also be edited by the user. Originally, folders on an iPhone could include up to 12 apps, while folders on iPad could include 20. In iOS 9, Apple updated folder sizes for iPad hardware, allowing for 16 apps per page, still at 15 pages maximum, increasing the total to 240 apps.[75]

Notification Center

Before iOS 5, notifications were delivered in a and couldn't be viewed after being dismissed. In iOS 5, Apple introduced , which allows users to view a history of notifications. The user can tap a notification to open its corresponding app, or clear it.[76] Notifications are now delivered in banners that appear briefly at the top of the screen. If a user taps a received notification, the application that sent the notification will be opened. Users can also choose to view notifications in modal alert windows by adjusting the application's notification settings. Introduced with iOS 8, widgets are now accessible through the Notification Center, defined by 3rd parties.

When an app sends a notification while closed, a red badge appears on its icon. This badge tells the user, at a glance, how many notifications that app has sent. Opening the app clears the badge.

Accessibility

iOS offers various accessibility features to help users with vision and hearing disabilities. One major feature, , provides a voice reading information on the screen, including contextual buttons, icons, links and other elements, and allows the user to navigate the operating system through gestures. Any apps with default controls and developed with a UIKit gets VoiceOver functionality built in. As part of a "Made for iPhone" program, introduced with the release of in 2013, Apple has developed technology to use and a special technology protocol to let compatible third-party equipment connect with iPhones and iPads for streaming audio directly to a user's ears. Additional customization available for Made for iPhone products include battery tracking and adjustable sound settings for different environments. Apple made further efforts for accessibility for the release of in 2016, adding a new pronunciation editor to VoiceOver, adding a Magnifier setting to enlarge objects through the device's camera, software support for deaf people to make phone calls from the iPhone, and giving tutorials and guidelines for third-party developers to incorporate proper accessibility functions into their apps.[81]

In 2012, Liat Kornowski from wrote that "the iPhone has turned out to be one of the most revolutionary developments since the invention of ", described Apple as "leading the way in assistive technology", with Sarah Herrlinger, Senior Manager for Global Accessibility Policy and Initiatives at Apple, stating that "We see accessibility as a basic human right. Building into the core of our products supports a vision of an inclusive world where opportunity and are barrier-free, empowering individuals with disabilities to achieve their goals".[83]

Multitasking

for iOS was first released in June 2010 along with the release of . Only certain devices—, , and 3rd generation—were able to multitask. did not get multitasking until iOS 4.2.1 in that November.

The implementation of multitasking in iOS has been criticized for its approach, which limits the work that applications in the background can perform to a limited function set and requires application developers to add explicit support for it.

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.:[91]

1. Background audio – application continues to run in the background as long as it is playing audio or video content[92]


2. Voice over IP – application is suspended when a phone call is not in progress[92]


3. Background location – application is notified of location changes[92]




5. Local notifications – application schedules local notifications to be delivered at a predetermined time[92]


6. Task completion – application asks the system for extra time to complete a given task[92]


7. Fast app switching – application does not execute any code and may be removed from memory at any time[92]

In iOS 5, three new background APIs were introduced:

1. Newsstand – application can download content in the background to be ready for the user[92]


2. External Accessory – application communicates with an external accessory and shares data at regular intervals[92]


3. Bluetooth Accessory – application communicates with a bluetooth accessory and shares data at regular intervals[92]

In iOS 7, Apple introduced a new multitasking feature, providing all apps with the ability to perform background updates. This feature prefers to update the user's most frequently used apps and prefers to use Wi-Fi networks over a cellular network, without markedly reducing the device's battery life.