swift | The Swift Programming Language | iOS library

Back-deploying concurrency to older OS versions bundles a concurrency runtime library along with your app with the support required for this feature, much like Swift used to do with the standard library prior to ABI stability in Swift 5, when Swift could be shipped with the OS.

This bundles parts of the Concurrency portions of the standard library (stable link) along with some additional support and stubs for functionality (stable link).

This bundling isn't necessary when deploying to OS versions new enough to contain these runtime features as part of the OS.

Since the feature on iOS 15+ (and associated OS releases) was stated to require kernel changes (for the new cooperative threading model) which themselves cannot be backported, the implementation of certain features includes shims based on existing functionality which does exist on those OSes, but which might perform a little bit differently, or less efficiently.

You can see this in a few places in Doug Gregor's PR for backporting concurrency — in a few places, checks for SWIFT_CONCURRENCY_BACK_DEPLOYMENT change the implementation where some assumptions no longer hold, or functionality isn't present. For example, the GlobalExecutor can't make assumptions about dispatch_get_global_queue being cooperative (because that threading model doesn't exist on older OSes), so when backporting, it has to create its own queue for use as the global cooperative queue. @objc-based actors also need to have their superclass swizzled, which doesn't need to happen on non-backdeployed runtimes. (Symbols also have to be injected in some places into the backdeploy libs, and certain behaviors have to be stubbed out, but that's a bit less interesting.)

Overall, there isn't comprehensive documentation on the exact differences between backdeploying and not (short of reading all of the code), but it should be safe to assume that the effective behavior of the backdeployed lib will be the same, though potentially at the cost of performance.

I've the same issue. If I launch Xcode using rosetta, it doesn't show anything. You must switch off rosetta and it works perfect.

It's a bit confusing. First, you'll need to import UniformTypeIdentifiers. Then, replace kUTTypeImage with UTType.image (the Swift version of UTTypeImage).

I've been getting the same error no matter what I've tried. I think there might be an error on setting the command line tools path with the Xcode version 13. So deleting XCode 13 (How to uninstall XCode) and reinstalling 12.5.1.(XCode12.5.1) solved the problem for me temporarily.

The key is to keep a reference to the Task, and if found, await its value.

Perhaps:

async/await might not be the proper paradigm if you want cancellation. The reason is that the new structured concurrency support in Swift allows you to write code that looks single-threaded/synchronous, but it fact it's multi-threaded.

Take for example a naive synchronous code:

xcodebuild and xcrun help build Xcode projects in a headless context, for example in CI setups. swift is the Swift REPL and is largely used for Swift on Server apps. As such, we can build apps without knowing about or using the tools regularly in mobile app development. We use xcodebuild and xcrun under the hood interacting with Xcode even though we don't realise it because they're bundled in Xcode's Command Line tools (documentation archive, but still relevant).

fastlane is an example CI tool that automates the build process, certificate signing, and interfacing with App Store Connect, using these tools.

xcodebuild is part of Xcode's bundled command-line tools package. From the manpages:

build Xcode projects and workspaces

xcodebuild builds one or more targets contained in an Xcode project, or builds a scheme contained in an Xcode workspace or Xcode project.

xcodebuild has lots of options and use cases. The options are equivalent to certain user actions within the Xcode IDE. Example usage:

Check https://developer.apple.com/forums/thread/696504 and re-download Xcode 13.2 directly from the releases section of the Apple Developer website: https://developer.apple.com/download/release/

EDIT: Xcode 13.2.1 version fixes this issue and can be downloaded from the Mac App Store.

Old Answer:

Apple has responded:

We're currently investigating this issue — thank you to those who have filed bug reports so far. To workaround this issue, please re-download Xcode 13.2 RC directly from the More Downloads page.

https://developer.apple.com/forums/thread/696504