Obsolete, unsupported.[citation needed] Drops support for the iPhone (1st generation), iPod Touch (1st generation) and, from iOS 4.3 onwards, for the iPhone 3G and iPod Touch (2nd generation).
iOS 4 is the
fourth major release of the
iOSmobile operating system developed by
Apple Inc., being the successor to
iPhone OS 3. It was announced at the Apple Special Event on April 8, 2010, and released on June 21, 2010. iOS 4 was the first version branded as "iOS" rather than "iPhone OS",[1] due to the release of the iPad. It was succeeded by
iOS 5 on October 12, 2011.[2]
iOS 4 introduced many features that have since become commonplace, such as folders on the home screen, significantly increasing the number of apps that can be displayed. Support for home screen wallpapers on the iPhone was also added, although limited to newer devices due to animation performance requirements. The operating system also added a multitasking feature, letting apps dealing with
Internet calling,
location and audio playback function in the background, whereas a similar but more restricted "Fast App Switching" technology enabled any app to be left inactive in the background while users switch to other apps. iOS 4 also added a system-wide spell checking feature, enabled
iBooks on iPhone, unified the
Mail inbox to combine content from different email providers, and introduced both
Game Center for social gaming and
FaceTime for
video calling.
The iOS 4 update introduced performance and battery problems on
iPhone 3G devices, with Apple investigating the matter and promising then-upcoming updates. However, the company became the subject of a lawsuit from an unsatisfied customer over the issues. Around the same time, the release of
iPhone 4 and its subsequent
antenna problems made Apple focus on unsuccessfully attempting to
patch the issues with software updates.
iOS 4 is the final version of iOS that features the iPod app for music and videos on iPhones. Starting with iOS 5, iPhones do not have the iPod app, but instead have the Music and Videos apps, as the
iPod Touch and
iPad do. It is also the last version of iOS that supports the iPhone 3G and
second-generation iPod Touch, up to version 4.2.1 (4.3 dropped support for both devices).
iPhone OS 4 was introduced at the Apple Special Event on April 8, 2010. At the
WWDC keynote address on June 7, 2010, it was renamed to iOS 4 in order to be more inclusive to the iPod Touch and iPad.[3]
iOS 4 was officially released on June 21, 2010.[3]
System features
Home screen
iOS 4 raised the maximum number of home screen apps from 180 to 2,160 due to the addition of folders. These folders would automatically be named based on the containing apps' respective
App Store category.[4] On the iPhone, the ability to choose wallpapers and see them on the home screen was also added, though the feature was notably absent from iPhone 3G and the second-generation iPod Touch due to poor performance of icon animations.[5] Additionally, the iPhone's dock was updated to be skeuomorphic, as with the Dock on the iPad and
Mac OS X, and no longer has a grey line underneath it; the icons were redesigned to match.
Multitasking
iOS 4 introduced multitasking. The feature allowed users to switch between apps instantly by clicking the home button two times. It was implemented in such a way that did not cause excessive battery drain. Multitasking was limited to apps dealing with
Internet calling,
location, and audio playback, while a similar "Fast App Switching" technology meant users could leave an app and enter another, with the original app remaining in the background until the user returns.[6][7] This feature was notably absent from iPhone 3G and the second-generation iPod Touch due to performance issues.
iOS 4 introduced a
spell checking feature that underlined misspelled words in red. Tapping on the word would provide a pop-up with a recommended replacement.[8]
iOS 4 introduced iPhone and iPod Touch support in iBooks, which was already included on the iPad. Though not a default app, it was available through the App Store.[10]
The Mail app featured a unified inbox on iOS 4, allowing users to see messages from all of their email accounts displayed together in a single inbox.[11] It also gained support for
MobileMe e-mail aliases and multiple
Exchange accounts for business users.[6]
iOS 4 added a new app called Game Center, an online multiplayer social gaming network, which allows users to invite friends to play games and to compare their scores on a leaderboard.[12][13] It was not available on the iPhone 3G.[13]
FaceTime
iOS 4 introduced FaceTime, a
videotelephony app that uses the device's camera to allow the user to make video calls with other FaceTime users.[14] This feature was absent from the iPhone 3G, second-generation iPod Touch,
iPhone 3GS, and third-generation iPod Touch due to the lack of required features, such as a front-facing camera.
Safari
The
Safari mobile
web browser on iOS 4 added
Bing as a search option in addition to
Google and
Yahoo!.[15]
Beginning with iOS 4.2.1, specific words or phrases on a page could be searched.[16]
Problems
Performance and battery issues
iPhone 3G users reported performance and battery issues after upgrading to iOS 4. Apple started an investigation of the matter in July 2010.[17] In November, Apple was sued for the issues, with an unsatisfied customer alleging "violating the Consumer Legal Remedies Act, unfair business practices, and false and deceptive advertising", with further allegations that Apple knew its software would cause problems on older models. Apple never responded to the allegations, but wrote in a reply to another unsatisfied customer in August 2010 that updates were "coming soon".[18][19]
Alarm clock
In all versions of iOS 4, the alarm clock in the clock app had a problem in DST when it would go off an hour too early or too late.[20]
Antenna problems
Upon its release, some iPhone 4 users reported having technical problems with the phone's antennas.[21] Apple attempted to fix the issue in software with iOS 4.0.1,[22] but failed to do so.[23]
Supported devices
iOS 4 drops support for the
first-generation iPhone and
first-generation iPod Touch due to hardware limitations, though the iPhone 3G did support iOS 4, despite it having the same processor as the first-generation iPhone. However, the iPhone 3G and iPod Touch (2nd generation) have limited support[a]
Fixes a bug that allowed a maliciously crafted
.tiff image to lead to arbitrary code execution[26]
Fixes a bug that allowed an attacker in a privileged network position to redirect FaceTime calls
Fixes multiple bugs that caused visiting a maliciously crafted website to lead to arbitrary code execution
Exclusive to iPhone 3GS, iPhone 4, and iPod touch (3rd generation):
Game Center, a service that allows syncing of game save data, achievements, and more. Game Center had previously been part of developer versions of iOS 4.[27]
Initial release on iPhone 4 (CDMA), as while 4.2.5 also came with the device, 4.2.6 was the first public version.
Bug fixes for personal hotspots
Initial Release
4.2.7
8E303
April 14, 2011
Fixes a bug that caused FaceTime calls to freeze
Updates SSL certificates after fraudulent certificates were issued by a Comodo affiliate registration authority
Fixes multiple bugs that caused viewing of a maliciously crafted website to lead to arbitrary code execution[34][35]
Bug Fixes
4.2.8
8E401
May 4, 2011
Fixes a bug that caused location to be reported incorrectly[36]
Bug Fixes
4.2.9
8E501
July 15, 2011
Fixes bugs that caused viewing a maliciously crafted PDF to cause arbitrary code execution
Fixes a bug that caused code running as user to gain system privileges[37]
It also patches the latest version of
JailbreakMe (JailbreakMe 3.0).
Bug Fixes
4.2.10
8E600
July 25, 2011
Fixes a bug that allowed an attacker in a privileged network position to capture and/or modify data in SSL/TLS-protected network sessions[37]
Bug Fixes
^Multitasking, home screen wallpapers and Bluetooth keyboard support are not available on both the iPhone 3G and iPod Touch (2nd generation), while Game Center, Apple's gaming network, was available on the iPod Touch (2nd generation) but not on the iPhone 3G.