Apple updated their developer support center with the latest stats on iOS 7 adoption. As of December 1st, 2013, 74% of all iOS devices are running iOS 7. 22% are running iOS 6 and 4% are running an earlier version. This puts iOS 7 in-line to be the fastest adopted OS in Apples history. iOS 6 took six months to get to 83% and iOS 7 will surely surpass that milestone.
This fast adoption rate makes life easier for developers. They can develop new software with the latest and greatest features without having to incorporate support for legacy operating systems.
Android has a much harder time with user adoption. This isn’t because of a lack of interest. Android device manufactures must produce a specific version of the OS for each device and carrier. After that is done it has to be tested by the carrier before the device manufacturer can push it out to their users.
Here are current Android adoption rates:
Jelly Bean 54.5%
Ice Cream Sandwich 18.2%
We will see a big jump in KitKat adoption as new devices are released over the next few months.