Everybody is aware of that Apple working methods have model numbers, like iOS 13.5.1 or macOS 10.15.5. However have you ever observed that Apple working methods even have construct numbers? For example, iOS 13.5.1 is construct quantity 17F80. However what does that imply?
To see your macOS model and construct numbers on a Mac, select Apple > About This Mac and click on the model quantity. In iOS or iPadOS, go to Settings > Common > About and faucet Software program Model. For watchOS, in your iPhone’s Watch app, go to Common > About and take a look at the Model line.
Though it’s simple to verify the construct variety of any working system you’re operating, Apple doesn’t publish a canonical checklist of them anyplace. For that info, head to Wikipedia’s iOS Version History, macOS Version History, watchOS, and tvOS articles or look within the MacTracker app (for the macOS construct numbers, you’ll must click on by from the model historical past article to the expanded article about every launch).
Apple makes a brand new construct of every working system at the very least each evening, so there’s a recent model prepared for the engineers every morning. Most of those builds are by no means launched exterior the corporate, in order that they don’t get an official model quantity like 13.5.1. However the engineers nonetheless want a solution to determine a specific construct. That’s what construct numbers are for. When you perceive methods to decode Apple’s construct numbers, you’ll be able to glean extra details about any given launch.
Understanding Apple Model and Construct Numbers
Apple’s two major working system strains, iOS and macOS, have unbiased model and construct quantity methods. iOS, iPadOS, watchOS, and tvOS share a standard system since they’re all derived from the iOS code base. (Solely Darwin-derived working methods—macOS, iOS, iPadOS, watchOS, and tvOS—use construct numbers. Basic Mac OS and iPod OS didn’t use the identical construct quantity system.)
As you recognize, each Apple working system launch has an official model quantity, composed of three components:
- Main model: For iOS, it’s incremented as soon as per yr for vital upgrades. For macOS, the most important model quantity has been 10 because the preliminary launch of Mac OS X, rendering it pointless up till the upcoming replace to macOS 11 Large Sur.
- Minor model: For iOS, the minor model is incremented as obligatory (normally three to 6 occasions) all through the lifespan of a serious model to mirror updates that include new options together with bug fixes. For macOS, the minor model is basically the most important model, incrementing for every annual named launch of macOS.
- Patch model: For iOS, the patch model increments as obligatory for bug repair updates to every minor launch. For macOS, Apple updates the patch model for each launch that’s greater than only a fast bug repair—these are referred to as “supplemental updates” and don’t get their very own model numbers. However their construct numbers change!
Right here’s a easy chart to assist make clear the official model numbering scheme.
An Apple construct quantity additionally has three components:
- Main model: Inside Apple, the most important model known as the construct prepare.
- Minor model: For iOS and its descendants, the minor model tracks with the minor launch; for macOS, it tracks with patch releases.
- Day by day construct model: The each day construct signifies what number of occasions Apple has constructed the supply code for the discharge because the earlier public launch.
To make this crystal clear, take a look at iOS 13.5.1, which is construct 17F80, and macOS 10.15.5 with its supplemental replace, which is construct 19F101.
|OS||Main||Minor||Day by day|
One tangentially associated notice: For macOS Large Sur, Apple up to date the most important model quantity to 11 and reset the minor model quantity to 0. This transfer might trigger issues for some apps that verify function availability by trying up the working system model. Since macOS’s main model quantity remained at 10 for thus lengthy, some builders received lazy and checked solely the minor model quantity. For sure, such sloppy code may break in Large Sur. Fortunately, as Howard Oakley explains, Apple has made some effort to mitigate this downside by having Large Sur return 10.16 slightly than 11.Zero in some conditions. Because of this apps ought to verify macOS APIs immediately for the existence of a specific function, slightly than assume it exists in a particular working system model simply because Apple first included it in that model or an earlier one.
Main Construct Quantity
Nowadays, the most important construct quantity for iOS modifications yearly. iOS 13’s main construct quantity is 17; iOS 14’s is 18.
|iOS, iPadOS, watchOS, and tvOS Construct Trains|
|iOS||iPadOS||watchOS||tvOS||Main Construct Quantity|
|iPhone OS 1||1–4|
|iPhone OS 2||5|
|iPhone OS 3||7|
|iOS 8||watchOS 1||12|
|iOS 9||watchOS 2||tvOS 9||13|
|iOS 10||watchOS 3||tvOS 10||14|
|iOS 11||watchOS 4||tvOS 11||15|
|iOS 12||watchOS 5||tvOS 12||16|
|iOS 13||iPadOS 13||watchOS 6||tvOS 13||17|
|iOS 14||iPadOS 14||watchOS 7||tvOS 14||18|
With macOS, the most important construct quantity additionally modifications with each vital launch, which happens yearly now, though much less incessantly previously.
|macOS Construct Trains|
|macOS Model||Main Construct Quantity|
|Mac OS X Public Beta||1|
|Mac OS X 10.Zero Cheetah||4|
|Mac OS X 10.1 Puma||5|
|Mac OS X 10.2 Jaguar||6|
|Mac OS X 10.Three Panther||7|
|Mac OS X 10.Four Tiger||8|
|Mac OS X 10.5 Leopard||9|
|Mac OS X 10.6 Snow Leopard||10|
|Mac OS X 10.7 Lion||11|
|Mac OS X 10.Eight Mountain Lion||12|
|Mac OS X 10.9 Mavericks||13|
|Mac OS X 10.10 Yosemite||14|
|Mac OS X 10.11 El Capitan||15|
|macOS 10.12 Sierra||16|
|macOS 10.13 Excessive Sierra||17|
|macOS 10.14 Mojave||18|
|macOS 10.15 Catalina||19|
|macOS 11.Zero Large Sur||20|
Minor Construct Letter
For iOS, the minor construct model normally modifications for every X.1 working system launch. It’s a letter, not a quantity, and customarily clambers its method up the alphabet. There are some discrepancies, corresponding to iOS 13.1 persevering with minor model A as an alternative of switching to B. Additionally, iOS 13.Three is minor model C, and iOS 13.Four is minor model E, skipping D. Extra on these oddities shortly.
|iOS 13 Minor Variations|
Issues are a bit completely different within the macOS world. As you’ll be able to see, the minor construct letter corresponds with the macOS patch launch quantity.
|Catalina Minor Variations|
Day by day Construct Quantity
Issues get attention-grabbing once we come to the each day construct quantity. Apple engineers increment it each time a brand new construct is made, normally each evening, however typically extra usually. The primary time Apple made an engineering construct of iOS 13, it was assigned construct quantity 17A1. The subsequent construct was 17A2. And so forth.
The primary delivery model of iOS 13.Zero was 17A577, which implies Apple made 577 builds of iOS 13 earlier than it shipped the primary copy to customers. The second delivery construct was iOS 13.1, construct quantity 17A844. It took an extra 267 builds to create iOS 13.1. Extra attention-grabbing are the construct numbers comparable to the patch releases.
|iOS 13 Patch Releases|
|iOS 13.1.2||17A860 and 17A861|
As you’ll be able to see, Apple was pushing these patch releases out shortly—there have been solely 10 builds between iOS 13.1 and iOS 13.1.1, solely 6 or 7 between 13.1.1 and 13.1.2, and solely 17 or 18 extra earlier than the discharge of iOS 13.1.3. I don’t know why iOS 13.1.2 had two construct numbers; iPadOS 13.1.2 shared solely the primary one, so maybe the second was particular to a specific iPhone mannequin or geographic space.
With macOS, the each day construct quantity is extra vital. As you’ve undoubtedly observed, when Apple is compelled to launch a fast bug repair replace for all of its working methods, it typically will get caught with macOS. iOS 13.5 went to 13.5.1, as an illustration, however macOS 10.15.5 was given a “supplemental replace” with no change within the official model quantity.
Fortunately, the construct quantity has no such limitation. As you’ll be able to see within the chart, the each day construct quantity modifications for the supplemental updates, enabling you to inform in case your copy of macOS has been up to date or not. That’s useful as a result of Apple normally backpatches supplemental updates into the replace they handle. So when you held off on putting in macOS 10.15.5 for every week, by the point you bought to it, it might have already included the macOS 10.15.5 Supplemental Replace (see “Kernel Vulnerability Causes Apple to Update All Operating Systems,” 1 June 2020). The one method you might inform what you had can be to take a look at the construct quantity.
|Catalina Supplemental Updates|
|macOS 10.15 Supplemental Replace||19A602|
|macOS 10.15 Revised Supplemental Replace||19A603|
|macOS 10.15.Four Supplemental Replace||19E287|
|macOS 10.15.5 Supplemental Replace||19F101|
Extracting That means from Construct Numbers
As you’ll be able to see, we will study helpful info from construct numbers. For example, watchOS 1 (12S506) has main construct quantity 12, the identical as iOS 8 (12A365), as a result of watchOS 1 is derived from the iOS Eight code base.
We will additionally inform iOS and iPadOS are constructed from the identical supply as a result of they’ve the identical construct quantity (17A577). Alternatively, we will inform tvOS 13 and watchOS 6 are derived from the iOS 13 code base, as a result of they’ve the identical main construct quantity, however are distinct branches, as a result of they’ve completely different minor construct numbers that aren’t used for iOS, with tvOS beginning at J and watchOS beginning at R.
Apple isn’t dogmatic about following these guidelines, or, to place it one other method, circumstances typically pressure the corporate to deviate from its guidelines. If it had adopted previous years, iOS 13.1 would have been 17Bxxx, nevertheless it was 17A844. This truth most likely signifies that Apple initially thought that iOS 13.1 was going to be iOS 13.0.1, nevertheless it ended up containing such vital modifications that the corporate determined to increment the minor model quantity slightly than the patch model quantity.
Final yr’s botched iOS launch displays that, with Apple releasing iOS 13.Zero and promising a fast replace to iOS 13.1 with options that weren’t prepared at launch (see “Apple to Ship iOS 13 on September 19th, iOS 13.1 on September 30th,” 10 September 2019, and “Features Added in iOS 13.1: Personal Automations, Driving ETA, and More,” 24 September 2019).
Equally, iOS 13.Three is 17C54 and iOS 13.Four is 17E255—what occurred to minor model D? That was assigned to iOS 13.3.1, which has construct quantity 17D50. Presumably, Apple had deliberate the discharge that ended up being iOS 13.3.1 to incorporate the various new options in iOS 13.Four however felt a urgent must push out a fast bug repair replace first. On this case, it was to handle the privateness issues surrounding the ultra-wideband know-how within the iPhone 11 (see “Apple Releases iOS 13.3.1, iPadOS 13.3.1, macOS 10.15.3, watchOS 6.1.2, and tvOS 13.3.1,” 28 January 2020).
There are undoubtedly many different tales behind jumps in construct numbers or construct numbers that skip round. An apparently lacking construct is likely to be destined for HomePod, or an unreleased product, or a product solely used internally at Apple. However what’s vital going ahead is that you simply now know methods to discover and decode the construct quantity related to any given working system launch. And with that info in hand, you’ll be able to draw varied conclusions in regards to the launch: how a lot work went into it, whether or not Apple was taken off guard by some bug report, or simply whether or not or not you’ve really acquired a supplemental replace.