IOS 4
iOS 4.0 only supported the iPhone and iPod Touch. iOS 4.0 was said to have more than 1500 new APIs for app creators. It also supported the multitasking feature for the first time. The final iOS version for the 2nd generation iPod Touch, and iPhone 3G is iOS 4.2.1. iOS 4.2.1 was the first version to make iPhones and iPads use the same operating system.