Apple has just released the first numbers of iOS 12's adoption rate on the App Store Developer Portal, and things look up from iOS 11 last year, with Apple's latest mobile OS that hits 50 percent adoption over qualified devices in 23 days (via  VentureBeat
By comparison, iOS 11, released September 19, 2017, failed 52 percent adoption until November 6 that year, taking 48 days or more twice as long as it took iOS 12 to beat its own 50 percent mark. Apple's portal also notes that the decision rate is even higher for devices released over the last four years, which affected 53 percent resolutions of iOS 1
Although it is difficult to compare directly from year to year, since we are largely On the basis of when Apple decides to release these numbers, iOS 10 was estimated to have reached 60 percent of devices for 44 days, while iOS 9 was installed at 67 percent after 64 days. Things look rosier compared to Android – after Google's latest update on September 28th, Android Oreo (released August 21, 2017) runs on only 19.2 percent of Android devices, after 403 days of availability. And it does not even count on Android Pie, Google's latest edition, as the company has yet to number.