Alongside the way in which to a full launch, Apple develops a number of variants of iOS all with a singular goal and a wholly completely different set of customers. Here is what they’re, after they’re used, and by whom.
Apple develops a number of iOS variants for each launch, and each has a singular goal
The top-consumer model of iOS is clearly freely obtainable to all, however there are numerous completely different phases of improvement and testing. Many of the distinctive variants of iOS are restricted to make use of inside Apple or related factories and distributors.
Earlier than Apple releases its first developer beta of an working system to registered builders, the OS has to undergo a collection of inside assessments to make sure correct performance. For that reason, iOS exists in a number of variants inside Apple, all of which may exist concurrently.
Some varieties of iOS are used to check the {hardware} parts of upcoming merchandise, whereas different variants are utilized by Apple’s software program improvement groups to create and take a look at completely different OS options and enhancements.
To higher illustrate Apple’s practices and basic strategy to iOS improvement, here is a short overview detailing the variations between the various OS variants used throughout the firm.
LLDiags – What Apple makes use of for low-level diagnostics
Maybe essentially the most primary of all, this model of iOS options just about no person interface. LLDiags is a specialised variant of iOS supposed for low-level diagnostics, mostly in factories.
Gadgets operating LLDiags function solely a easy diagnostic picture, identified internally as “Diags.” The diagnostic picture shows a primary person interface, which can be utilized to carry out assessments or reboot the system.
iPhone 8 operating Diags – YouTube printscreen from AppleDemo’s video
When not in Diags, units operating the LLDiags model of iOS will often boot straight into restoration mode, and won’t show anything aside from the restoration mode emblem. The filesystem typically accommodates the naked minimal, sufficient for the system to have the ability to boot, however not a lot else.
Apple’s engineers are stated to work together with these units via a command-line interface, by way of a linked laptop.
NonUI – What Apple’s {hardware} engineers and calibration machines use
The NonUI variant of iOS was created as a method of separating the work executed by Apple’s software program and {hardware} improvement groups.
The software program engineering (SWE) staff labored on what would finally turn into the Launch model of iOS, with the person interface the buyer would see. The {hardware} staff was given one thing else.
The {hardware} engineering groups inside Apple (HWTE) weren’t given entry to the traditional person interface. As an alternative, they relied on a make-shift model of the iPhone’s working system that had a rudimentary UI, solely supposed to check {hardware} parts resembling buttons, ports, cameras, audio system, and sensors.
The next two early iPhone function the proper illustration of the variations between InternalUI and NonUI variants of iOS.
The 2 “Acorn” prototypes of the unique iPhone illustrate the distinction between InternalUI and NonUI
Whereas Apple’s software program engineers labored on an iPod-esque interface with a click on wheel, the {hardware} improvement staff labored on a model of the working system that featured easy squares and rectangles as buttons.
These early prototypes ran an working system referred to as AcornOS, and are generally known as the “Acorn Prototypes” by collectors.
Because the iPhone developed, so did the NonUI variant of its working system. Later prototypes of the unique iPhone featured a model of the working system with the arguably inappropriately named “SkankPhone.”
Early variations of SkankPhone’s “About” part listed the working system identify as “OS X” slightly than “iPhoneOS.” This completely showcases the separation between Apple’s {hardware} and software program groups.
The corporate’s inside working methods are full of varied inside jokes, crude drawings, and memes. Some variations even include pop-culture references, like inside variations of watchOS which include references to characters from the present “The Simpsons.”
The SkankPhone app would, as an illustration, show completely different messages on the backside of the display screen. A few of them embrace: “Skank is the brand new black” and “Say hiya to the Newton MessagePad 3000.”
iPhone operating SkankPhone – YouTube Printscreen from Michael MJD
The app would later evolve into SwitchBoard, a rudimentary launcher for NonUI purposes and environments resembling BurnIn. SwitchBoard exists and features independently, with out the necessity for SpringBoard or UIkit – that are used to show the usual iOS UI on different variants of iOS.
Whereas SkankPhone was stored round for a number of extra years, the app was finally discontinued with iOS 6.0, with different inside purposes taking its place. Because the iPhone obtained increasingly {hardware} options, its inside working system wanted extra purposes to check new parts.
Inner NonUI working methods additionally typically mirror modifications that have an effect on the consumer-oriented model of iOS, referred to as “Launch” iOS inside Apple. On this regard, NonUI variations after iOS 7.0 undertake a flat look in some areas.
When it comes to particular options, NonUI builds of iOS typically function a improvement kernelcache, improvement iBoot, and assist a number of {hardware} configurations. This sort of iOS also can include references to unreleased or scrapped units such because the N89 iPhone or J98/J99 iPad.
Through the years, Apple has created particular variants of NonUI iOS, to be used in manufacturing strains or part calibration machines such because the Horizon machine. All of those OS variations nonetheless fall underneath the class of NonUI, which continues to be used inside Apple and inside factories.
Inner UI – What Apple’s software program engineers use
Arguably essentially the most fascinating, and most attention-grabbing variant of iOS is Inner UI. Because the identify itself implies, one of these iOS options an inside and sometimes pre-production variant of the person interface discovered on iOS.
Because of this InternalUI variations of iOS can include implementations of unreleased options, unannounced merchandise, experimental take a look at environments or alternate design selections Apple developed.
An alternate multitasking view may be seen in an inside model of iOS 4, footage of which had been posted to a Vietnamese web site in 2011.
The multitasking view in iOS 4 might have been very completely different
Along with the usual person interface, InternalUI builds of iOS typically include specialised settings which have an effect on the looks or functioning of the working system. This sort of iOS additionally comes with numerous internal-use purposes, which may include codenames or early prototypes of latest OS options.
Notably, internalUI builds of iOS include built-in bug reporting choices, that are processed via the the Radar software. To report a bug, an Apple worker would “file a radar.”
The InternalUI variant of iOS often accommodates assist for each production-fused and development-fused iPhones, together with assist for improvement boards and FPGAs in some situations. InternalUI builds include debug variations of iBoot as nicely.
Inner UI variations of iOS additionally exist in a separate variant known as “Desense,” which regularly has lots of the identical inside purposes and settings, though the contents of one of these iOS can differ quite a bit.
Every so often, an inside construct of iOS makes its technique to most people, or to communities of collectors and fanatics.
In early 2020, an inside model of iOS 14 from a development-fused iPhone 11 was leaked to some people and finally made its technique to the press. The model contained references to AppClips, Wallpaper Collections, and Widgets.
Whereas AppClips and Widgets each made their debut later in 2020 with iOS 14, the Wallpaper Collections function was solely launched with iOS 16 two years later. This serves as an indicator of how cautious Apple is in relation to high quality management.
VendorUI – What’s utilized in factories for testing
Whereas each InternalUI and the end-consumer variant iOS function the usual iOS person interface in its entirety, the identical can’t be stated for VendorUI.
VendorUI is a specialised kind of iOS despatched out to factories and related distributors for high quality management testing. Whereas the software program does function SpringBoard and the important thing components of the iOS UI, the working system typically doesn’t have all default purposes current.
This model of iOS is often despatched out together with a guidelines of apps current throughout the construct. Entry to it’s closely restricted to stop new function leaks.
In March of 2024, a reputable personal account on X claimed that Apple had begun distributing inside builds of the VendorUI model of iOS 18.
CarrierOS – What carriers want to check performance
CarrierOS is a variant of iOS that’s typically practically an identical to the variations of iOS that Apple makes obtainable to most people.
Distributed to carriers worldwide, one of these iOS accommodates the usual end-user interface together with specialised apps and utilities that could be of use to carriers.
The working system accommodates purposes resembling “E911Tester,” which is used to check the E-911 emergency name system on iPhones.
Launch iOS – What the top shopper will get to expertise
That is the model of iOS utilized by nearly everybody with an iPhone. Except you are an Apple engineer, you have probably solely seen inventory variations of iOS, which Apple refers to as “Launch” internally.
Developer betas, public betas and commonplace .ipsw recordsdata all fall underneath the Launch class, as they don’t function any inside instruments or purposes.
Curiously, inside distributions of Launch iOS additionally exist. These distributions function the identical filesystem as publicly obtainable variations of iOS, with the addition of improvement iBoot in some circumstances.
What does this all imply?
The existence of various variants of iOS serves as a sign of Apple’s dedication to the standard of its merchandise. New releases of the working system undergo a number of rounds of testing, even earlier than the primary developer betas are despatched out in June of yearly.
Apple additionally makes use of its working methods for outgoing high quality management, to make sure that new iPhones are all as much as commonplace, and that faulty items don’t get shipped.