iOS 4

The concept of multitasking started with iOS4 and also the first of its kind which dropped support for devices like the original iPhone and iPod Touch. One November 22^nd 2010, in the 4.2.1 version of the OS iPad compatibility were added.

The replacement of iOS 4.2 by 4.2.1 due to a bug fix led Apple to release two Grand Masters (4.2 GM and 4.2.1 GM).

iOS 5

iOS 5 is the only Apple OS that was released for all the device at a same time, the OS was released on June 6^th 2011. The devices that got the update are iPhone 3GS, the new iPhone 4 which was released, iPhone 4S and iPod Touch. As for iPad and iPad 2 it was released on October 12^th 2011 and the latter version 5.1.1 is the last of the OS update released for iPad (1^st gen) and iPod Touch (3^rd gen). There were 4 versions on a whole which opened the new dimension of mobile experience.

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