Multitasking (iOS): Difference between revisions

Revision as of 07:27, 30 August 2013

Revision as of 13:13, 14 September 2013

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On [[iOS]], '''multitasking''' is a feature available in [[iOS 4]] or later that allows multiple [[mobile app|applications]] to run and perform tasks at the same time.

[[Computer multitasking|Multitasking]] for iOS was first released in June 2010 along with the release of [[iOS 4|iOS 4.0]].<ref name=HuffPost1>{{cite web|title=iOS 4 iPhone Update RELEASED: A Guide To iOS 4|url=http://www.huffingtonpost.com/2010/06/21/ios-4-iphone-update-relea_n_619343.html|publisher=[[The Huffington Post]]|accessdate=April 13, 2013|date=June 21, 2010}}</ref><ref name=PCMag1>{{cite web|last=Albanesius|first=Chloe|title=Apple iPhone iOS 4 Software Update Expected Monday|url=http://www.pcmag.com/article2/0,2817,2365351,00.asp|publisher=[[PC Mag]]Magazine|accessdate=April 14, 2013|date=June 21, 2010}}</ref> Only certain devices—[[iPhone 4]], [[iPhone 3GS]], and [[iPod Touch]] 3rd generation—were able to use multitasking.<ref name=ArsTechnica1>{{cite web|last=Cheng|first=Jacqui|title=Ars reviews iOS 4: what’s new, notable, and what needs work|url=http://arstechnica.com/apple/2010/06/ars-reviews-ios-4-whats-new-and-notable/|publisher=[[Ars Technica]]|accessdate=April 14, 2013|date=June 21, 2010}}</ref> The [[iPad]] did not get multitasking until the release of [[iOS 4|iOS 4.2.1]] in November 2010.<ref name=TheRegister1>{{cite web|last=Ray|first=Bill|title=iOS 4.2 multi-tasking comes to the iPad|url=http://www.wired.com/gadgetlab/2010/09/ipad-ios42/|publisher=[[The Register]]|accessdate=April 14, 2013|date=November 22, 2010}}</ref> Currently, multitasking is supported on iPhone 3GS or newer, iPod Touch 3rd generation or newer, and all iPad models.<ref name=Apple1>{{cite web|url=http://support.apple.com/kb/ht4211 |title=iOS: Understanding multitasking |publisher=Apple |accessdate=2013-09-14}}</ref>

Implementation of multitasking in iOS has been criticized for its approach, that limits the work that applications in the background can perform to a limited function set, and for requiring application developers to add explicit support for it.<ref name="ArsTechnica1" /><ref name="PCWorld2">{{cite web|last=Newman|first=Jared|title=Multitasking With iOS 4 is Horrible: Apple Blew It|url=http://www.pcworld.com/article/199528/Multitasking_With_iOS_4_is_Horrible_Apple_Blew_It.html|publisher=[[PCWorld]]PC World|accessdate=April 14, 2013|date=June 22, 2010}}</ref>

==Features==

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[[File:IOS Multitasking Bar.png|right|thumb|The multitasking bar on iOS 4]]

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.<ref>{{cite web|last=Ritchie |first=Rene |url=http://www.imore.com/ios-4-walkthrough |title=iOS 4 walkthrough |publisher=iMore |date=2010-06-14 |accessdate=2013-09-14}}</ref>  Starting with iOS 4, on third-generation and newer iOS devices, multitasking is supported through seven background  APIs:<ref>{{cite web|last=Ritchie |first=Rene |url=http://www.imore.com/apple-announces-multitasking-iphone-40 |title=Apple announces multitasking for iPhone OS 4 (iPhone 3GS/iPod touch G3 only) |publisher=iMore |date=2010-04-08 |accessdate=2013-09-14}}</ref>

# Background audio – application continues to run in the background as long as it is playing audio or video content<ref>{{cite web|url=https://developer.apple.com/library/ios/documentation/iPhone/Conceptual/iPhoneOSProgrammingGuide/ManagingYourApplicationsFlow/ManagingYourApplicationsFlow.html#//apple_ref/doc/uid/TP40007072-CH4-SW20 |title=iOS App Programming Guide: App States and Multitasking |publisher=Apple Developer |accessdate=2013-09-14}}</ref>

# Voice over IP – application is suspended when a phone call is not in progress<ref name="AppleDev1" />

# Background ___location – application is notified of ___location changes<ref name="AppleDev1" />

# [[Apple Push Notification Service|Push notifications]]

# Local notifications – application schedules local notifications to be delivered at a predetermined time<ref name="AppleDev1" />

# Task completion – application asks the system for extra time to complete a given task<ref name="AppleDev1" />

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===Fast app switching===

Fast app switching allows apps to pause and resume themselves quickly and easily change to other apps.<ref name="AnandTech1">{{cite web|last=Shimpi|first=Anand|title=Apple's iOS 4 Explored|url=http://www.anandtech.com/show/3779/apples-ios-4-explored/2|publisher=[[AnandTech]]|accessdate=April 14, 2013|date=June 22, 2010}}</ref> An app that is on the screen is considered "running", while an app that is not on screen but is still in memory is considered "suspended".<ref name="PCWorld1">{{cite web|last=Perenson|first=Melissa|title=Multitasking on Apple's iPhone 4: How Does It Work?|url=http://www.pcworld.com/article/198296/iphone_4_multitasking.html|publisher=[[PCWorld]]PC World|accessdate=April 14, 2013|date=June 8, 2010}}</ref> All apps that are built with iOS 4 SDK support fast app switching if running on iOS 4 and a compatible device.<ref name="AppleDev1">{{cite web|url=https://developer.apple.com/library/ios/#releasenotes/General/WhatsNewIniOS/Articles/iPhoneOS4.html#//apple_ref/doc/uid/TP40009559-SW1 |title=What's New in iOS: iOS 4.0 |publisher=Apple Developer |accessdate=2013-09-14}}</ref> Users can utilize fast app switching by activating the multitasking bar, which can be displayed by double-tapping the home button.<ref name="ArsTechnica1" /><ref name="PCWorld1" />

===Task completion===

Task completion allows apps to continue a certain task after the app has been suspended.<ref name="MacWorld1">{{cite web|last=Snell|first=Jason|title=Inside iPhone 4.0's multitasking|url=http://www.macworld.com/article/1150496/multitasking_iphone.html|publisher=[[MacWorld]]Macworld|accessdate=April 14, 2013|date=April 8, 2010}}</ref><ref name="CNet1">{{cite web|title=Apple iPhone 4|url=http://reviews.cnet.com/iphone-4-review|publisher=[[CNet]]CNET|accessdate=April 14, 2013|date=June 23, 2010}}</ref> As of iOS 4.0, apps can request up to ten minutes to complete a task in the background.<ref name="iLounge1">{{cite web|last=Hollington|first=Jesse|title=Instant Expert: Secrets & Features of iOS 4|url=http://www.ilounge.com/index.php/articles/comments/instant-expert-secrets-features-of-ios-4/|publisher=[[iLounge]]|accessdate=April 14, 2013|date=June 21, 2010}}</ref>

==See also==