Will updated apps still run on older macOS?
It may seem strange, but each new version of macOS brings a hidden feature that determines which older versions of macOS are supported by software. That’s largely set by those targeted by the new version of Xcode that supports the new macOS, in its minimum deployment target. This article explains how that works, and why you’ll see an increasing number of updates that require Big Sur or later over the coming year.
The largest developers like Microsoft and Adobe operate their own policy for supporting older versions of macOS, and in most cases follow Apple’s unwritten rules, in supporting the current macOS release, and the two previous versions. So, once their apps are fully compatible with Sequoia, you should expect them to support macOS 13 Ventura and later.
Smaller and independent developers usually try to support a wider range of macOS versions, but as most use Xcode to build their software, they’re dependent on the deployment targets supported by Xcode. This is where it gets more complicated.
Xcode support
Alongside Sequoia in beta-testing is Xcode 16, due for release at about the same time. That runs on late versions of Sonoma (14.5 or later) and Sequoia, and is the first version of Xcode that can build apps that make use of new features in Sequoia, the latest SDK (software development kit) supported by Xcode 16. Apple doesn’t update older versions of Xcode to support newer macOS, so a developer who’s still using Xcode 15 generally can’t use features introduced in Sequoia in their apps.
To make this a bit more complicated, that isn’t always so. For example, my macOS virtualisation apps Viable and Vimy are built using Xcode 15, but when they’re used in Sequoia they can now create VMs that support Apple ID, a new feature in Sequoia. However, other new virtualisation features such as support for USB devices will only be available to virtualisers built using Xcode 16, as they require the Sequoia SDK, which isn’t available in Xcode 15. Similarly, we don’t yet know whether Sequoia’s new AI Writing Tools will work with existing apps built for Sonoma rather than Sequoia.
Each version of Xcode has four compatibilities:
The minimum macOS required to run that version of Xcode; for Xcode 16, that’s macOS 14.5 or later.
The latest SDK it supports; for Sequoia support, that’s Xcode 16.
The hardware architectures it supports; Apple silicon was first supported by Xcode 12 (ish), so that’s not important here.
The minimum deployment target, or the oldest version of macOS for which it has an SDK; for Xcode 14 and later, including version 16, that’s macOS 10.13 High Sierra.
Of those, it’s the last that determines which older versions of macOS can be supported by apps built with that version of Xcode.
Minimum deployment target
Xcode versions 12 and 13 have a minimum deployment target of macOS 10.9, so apps built with them could support macOS as old as Mavericks from 2013. When Apple introduced Xcode 14 there were many complaints that its minimum deployment target rose to macOS 10.13 High Sierra. Apple appears to have listened, and the new Xcode for Sequoia, version 16, keeps the same minimum deployment target of 10.13.
However, it’s still not that simple. Apple recommends that developers using Xcode 16 build for macOS 11 Big Sur, the oldest version provided in the popup menu used to set the minimum deployment target. To build for older versions of macOS, the developer has to type the version in. Surprisingly, at present at least, Xcode 16 is happy to build for macOS 12 Sierra as a target, although whether that would work in reality isn’t clear.
Thus, when a developer is picking the minimum deployment target, the oldest version of macOS supported by a new app or update, the new Xcode can still support 10.13, but nudges the choice to Big Sur.
Code in an app also has to be compatible with all versions of macOS from its minimum deployment target. If a developer sets that too low, then they may well have to write conditional code to cater for differences in features across the whole range of target versions of macOS. That’s determined by what the app does, and how it does it: an app working with a newer feature such as Live Text can’t use that in macOS older than Monterey, as that’s when it was introduced. Feature support becomes most critical with SwiftUI, which wasn’t introduced until Catalina, and has changed greatly since.
SwiftUI
Like all precocious youngsters, SwiftUI has seen extensive changes since its introduction in 2019. Prior to macOS 13, support for key features in macOS apps is sufficiently limited to make it quite a challenge for a substantial app to rely largely or completely on SwiftUI. Even more recent versions of macOS use different calls to the API. For example, adding colour to Text in macOS 13 and earlier is performed by setting its foregroundColor; from macOS 14 onwards, that has to be its foregroundStyle instead. That can be accommodated with conditional code if the developer wishes.
Don’t be in the least bit surprised if apps that have switched to using SwiftUI for their interface require a minimum macOS version of 13 or 14, and it may not be long after the release of Sequoia that you start coming across the first relying on macOS 15.
Summary
Apps from major vendors like Microsoft and Adobe are likely to limit support to macOS 13, 14 and 15 once they’re fully compatible with Sequoia.
Other developers should still be able to support back to High Sierra, although Apple is encouraging all to build for Big Sur and later.
Support for older macOS also depends on whether an app requires features only available in more recent versions of macOS.
SwiftUI apps are likely to be the exception, and require Ventura or Sonoma.
