The iOS 4 is an operating system that was designed and developed especially for iPhone and iPad by Apple from 2010 to 2011. The system has been released on June 21, 2010, and was preinstalled on the iPhone 4, iPod touch 4th Generation, iPad 2, and Apple TV 2nd Generation.
This software gets the last update (4.3.5) on July 25, 2011, and later has been replaced by a newer version of iOS 5.
The new operating system introduced folders on the home screen, significantly increasing the number of apps that can be displayed. Support for custom wallpapers 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.
Today iOS 4 is 12 years old!
iOS 4 General Information
| Released | June 21, 2010 |
| Original Price | Free |
| System Requirements | iPhone 3G iPhone 3Gs iPhone 4 iPod touch 2nd Generation iPod touch 3rd Generation iPod touch 4th Generation iPad iPad 2 Apple TV 2nd Generation |
| Distribution | iTunes Apple TV Software Update |
Versions
| Versions | Build | Release Date |
| iOS 4.0 | 8A293 | June 21, 2010 |
| iOS 4.0.1 | 8A306 | July 15, 2010 |
| iOS 4.0.2 | 8A400 | August 11, 2010 |
| iOS 4.1 | 8B117 | September 8, 2010 |
| iOS 4.1 (Apple TV 4.0) | 8M89 | September 1, 2010 |
| iOS 4.2 (Apple TV 4.1) | 8C150 | November 22, 2010 |
| iOS 4.2.1 | 8C148 8C148a | November 22, 2010 |
| iOS 4.2.1 (Apple TV 4.1.1) | 8C154 | December 14, 2010 |
| iOS 4.2.5 | 8E128 | January 11, 2011 |
| iOS 4.2.6 | 8E200 | January 31, 2011 |
| iOS 4.2.7 (iPhone 4 CDMA) | 8E303 | April 14, 2011 |
| iOS 4.2.8 (iPhone 4 CDMA) | 8E401 | May 4, 2011 |
| iOS 4.2.9 (iPhone 4 CDMA) | 8E501 | July 15, 2011 |
| iOS 4.2.10 (iPhone 4 CDMA) | 8E600 | July 25, 2011 |
| iOS 4.3 | 8F190 | March 4, 2011 |
| iOS 4.3 (Apple TV 4.2) | 8F191m | March 4, 2011 |
| iOS 4.3 (Apple TV 4.2.1) | 8F202 | March 22, 2011 |
| iOS 4.3 (Apple TV 4.2.2) | 8F305 | May 11, 2011 |
| iOS 4.3 (Apple TV 4.3) | 8F455 | August 1, 2011 |
| iOS 4.3.1 | 8G4 | March 25, 2011 |
| iOS 4.3.2 (4.2.7 for iPhone 4 CDMA) | 8H7 8H8 | April 14, 2011 |
| iOS 4.3.3 (4.2.8 for iPhone 4 CDMA) | 8J2 8J3 | May 4, 2011 |
| iOS 4.3.4 (4.2.9 for iPhone 4 CDMA) | 8K2 | July 15, 2011 |
| iOS 4.3.5 (4.2.10 for iPhone 4 CDMA) | 8L1 | July 25, 2011 |