Well ahead of the first 72 hours of release, the latest version of Apple's mobile operating system iOS 9 has cracked
the 25 percent mark of all active iOS users, according to live data from analystics firm Mixpanel. This compares favorably to similar percentages for iOS 7, which reached 26 percent after four days of release, but is a little behind figures for iOS 8's earliest days. As others have pointed out, iOS 9's 25.74 percent (as of 10PM PT on Friday) is a significantly higher percentage than the percentage of users running the latest major Android release, Lollipop (5.x).
Lollipop, which is due to be replaced in a few weeks with a new release dubbed "Marshmallow," may never reach more than 25 percent of the active Android user base before the changeover due to fragmentation of Google's mobile operating system by carriers, which slows adoption and renders many devices prematurely obsolete. However, it should be noted that more users in total are still running Lollipop than iOS 9, and it will likely take the new OS around half of its annual life cycle to match the size of Lollipop's user base.
Still, the advantage in both the ability and willingness of most active iOS device owners to update to the latest release is a definite plus for owners, and particularly for developers. It allows them to focus support on just the current and most recent iOS releases going back no more than two years, instead of having to tailor applications to run on specific versions of Android or selected devices that can handle the latest version, or opt to try and support various releases on myriad devices with wildly different spec sheets released over the last five years or more, as Android developers must.
The latest incarnation, Lollipop, is nearly 11 months old, and currently on just 21 percent of Android devices. The previous release, KitKat from 2013, is now running on 40 percent of Android devices, while the previous release to that, 2012's Jelly Bean, holds 30 percent.
By contrast, iOS 8 was running on just over 92 percent of active iOS devices the day before iOS 9 came out, and still accounts for 68 percent of users three days later. Older iOS systems continue the slow dwindling, which has accelerated over the last three days as some holdout users finally upgrade. Previous iOS versions in total accounted for 8.78 of active iOS devices early Wednesday morning; it is now down to 6.6 percent.
The release of iOS 9 may also attract users that feared upgrading from iOS 7 due to concerns about speed or storage requirements, an issue that was widely discussed after owners of iPhone 4s units complained that the upgrade had made their devices slower. Optimization and other techniques in iOS 9, however, have reduced the size of the installer from 4.58GB for iOS 8 to just 1.3GB, and this includes the addition of numerous new features, improvements, bug fixes, and the occasional revamp.
Early reports from users suggest that iOS 9 runs well on earlier supported hardware due to lower RAM and storage requirements, but as with iOS 8 some features are unavailable on older models -- and indeed, a few features (such as 4K video support) are limited to just the latest models of iPhones and iPads.