Folders iOS 4 added folders for apps, which raises the maximum number of home screen apps from 180 to 2,160. These folders would automatically be named based on the containing apps' respective
App Store category.
Multitasking iOS 4 introduced multitasking, replacing the home button shortcuts feature which had a similar albeit more limited function. It allows 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. 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.
Camera The Camera app now supports 5x digital zoom.
Apps 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. It also gained support for
MobileMe e-mail aliases and multiple
Exchange accounts for business users. It was not available on the iPhone 3G. 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!. Beginning with iOS 4.2.1, specific words or phrases on a page could be searched.
Features added on the iPhone inherited from the iPad On the iPhone, the ability to choose wallpapers and see them on the home screen was also added, and the iPad had its ones replaced to be consistent, though the feature was notably absent from iPhone 3G and the second-generation iPod Touch due to poor performance of icon animations. 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. 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. == Problems ==