iOS 4 FeaturesMultitasking
Now you can run your favorite third-party apps — and switch between them instantly — without slowing down the performance of the foreground app or draining the battery unnecessarily. (only for Apple iPhone 3GS)
Organize apps into folders with drag-and-drop simplicity. Get faster access to your favorites and browse and manage up to 2160 apps.
Even better Mail
See messages from all your accounts in a unified inbox, organize messages by threads, open attachments in third-party apps, and more.
More than a great ebook reader, iBooks is also an amazing place to browse and shop for books, day or night.2
Create custom playlists right on your iPhone.
5x digital zoom
Get closer to your subjects by zooming in up to 5x.
Tap to focus video
While shooting video, tap the display to choose where to focus.
Faces and Places in Photos
View photos based on who’s in them and where they were taken.3
Home screen wallpaper
Change the background wallpaper on your Home screen.
Send apps as gifts to your friends or family.
A built-in dictionary automatically suggests words and corrects spelling. It works in Mail, Notes, and other apps.
Wireless keyboard support
Pair a keyboard based on Bluetooth wireless technology with your iPhone.
How to Install iOS 4
For more information please visit the Apple Web Site.