# Core Libraries **URL:** https://forums.swift.org/c/development/corelibs/8.md [Latest](https://forums.swift.org/latest.md) · [Categories](https://forums.swift.org/categories.md) · [Tags](https://forums.swift.org/tags.md) --- ## [About the Core Libraries category](https://forums.swift.org/t/about-the-core-libraries-category/14)
**Author:** [@system](https://forums.swift.org/u/system)\ **Replies:** 0\ **Last updated:** [January 18, 2018, 7:44am UTC](https://forums.swift.org/t/about-the-core-libraries-category/14 "2018-01-18T07:44:46Z")
For developers to discuss the implementation of the Swift core libraries. The Swift Core Libraries project provides higher-level functionality than the Swift standard library. These libraries provide powerful tools that… --- ## [Request for permissions in swiftlang GitHub org](https://forums.swift.org/t/request-for-permissions-in-swiftlang-github-org/89540)
**Author:** [@MahdiBM](https://forums.swift.org/u/MahdiBM)\ **Replies:** 1\ **Last updated:** [September 14, 2026, 10:48pm UTC](https://forums.swift.org/t/request-for-permissions-in-swiftlang-github-org/89540 "2026-09-14T22:48:43Z")
Hello all. Per "A new Member contributor role that can trigger CI" which was announced by @ahoppen 1.5 years ago, I'd like to request access to have permission to run CI in swiftlang repositories. Swiftlang / Apple or… --- ## [Is corelibs-foundation still accepting fixes?](https://forums.swift.org/t/is-corelibs-foundation-still-accepting-fixes/85149)
**Author:** [@willft](https://forums.swift.org/u/willft)\ **Replies:** 8\ **Last updated:** [July 24, 2026, 2:26am UTC](https://forums.swift.org/t/is-corelibs-foundation-still-accepting-fixes/85149 "2026-07-24T02:26:20Z")
What's the current status of issues/PRs on swift-corelibs-foundation for fixing broken functionality (not implementing new functionality)? Are new changes being accepted? I'm asking because I just bumped into a FileMana… --- ## [Formalizing the unavailability of Core Foundation](https://forums.swift.org/t/formalizing-the-unavailability-of-core-foundation/40216)
**Author:** [@millenomi](https://forums.swift.org/u/millenomi)\ **Replies:** 23\ **Last updated:** [July 20, 2026, 4:56pm UTC](https://forums.swift.org/t/formalizing-the-unavailability-of-core-foundation/40216 "2026-07-20T16:56:49Z")
CF on platforms other than Darwin has been a topic on which there has been a consistent response, but that consistent response always included the caveat that things were in a transitory state. The commitment I've echoed… --- ## [\[GSoC 2026\] Interested in Documentation Coverage Project](https://forums.swift.org/t/gsoc-2026-interested-in-documentation-coverage-project/85315)
**Author:** [@shashank28](https://forums.swift.org/u/shashank28)\ **Replies:** 9\ **Last updated:** [March 20, 2026, 7:23am UTC](https://forums.swift.org/t/gsoc-2026-interested-in-documentation-coverage-project/85315 "2026-03-20T07:23:49Z")
Hello everyone, My name is Shashank Yadav and I am a second-year Computer Science student at SRM Institute of Science and Technology. I am interested in applying for Google Summer of Code 2026 with the Swift project. A… --- ## [Missing symbol with static FoundationEssentials on Linux](https://forums.swift.org/t/missing-symbol-with-static-foundationessentials-on-linux/85044)
**Author:** [@keeshux](https://forums.swift.org/u/keeshux)\ **Replies:** 3\ **Last updated:** [February 27, 2026, 11:57am UTC](https://forums.swift.org/t/missing-symbol-with-static-foundationessentials-on-linux/85044 "2026-02-27T11:57:28Z")
Hi, I haven't had major issues with linking to the resources in swift\_static until I started using FoundationEssentials on Linux. IIRC, this wasn't happening with the full Foundation library, but I can be wrong. Maybe I… --- ## [New to swift and IOS dev, attempting to implement a simple button that loads persistent data with little luck](https://forums.swift.org/t/new-to-swift-and-ios-dev-attempting-to-implement-a-simple-button-that-loads-persistent-data-with-little-luck/85029)
**Author:** [@HelpNeeder404](https://forums.swift.org/u/HelpNeeder404)\ **Replies:** 2\ **Last updated:** [February 26, 2026, 8:28pm UTC](https://forums.swift.org/t/new-to-swift-and-ios-dev-attempting-to-implement-a-simple-button-that-loads-persistent-data-with-little-luck/85029 "2026-02-26T20:28:56Z")
As the title states, I am attempting to implement a button that loads persistent data from a class (see below). Button("Reload Data") { while tableData2.isEmpty == false{ tableData2.remove(at: 0) }… --- ## [Swift Subprocess - Failed to spawn UnderlyingError(rawValue: 20](https://forums.swift.org/t/swift-subprocess-failed-to-spawn-underlyingerror-rawvalue-20/84283)
**Author:** [@psummerland](https://forums.swift.org/u/psummerland)\ **Replies:** 4\ **Last updated:** [January 24, 2026, 1:00pm UTC](https://forums.swift.org/t/swift-subprocess-failed-to-spawn-underlyingerror-rawvalue-20/84283 "2026-01-24T13:00:45Z")
Here is a simple program that should not crash. (Amazingly, it runs fine in Xcode Version 26.2 (17C52).) I am running Tahoe 26.2. Output \[I\] release\> ./subprocess-issue Hi Swift/ErrorType.swift:254: Fatal error: Error… --- ## [Subprocess I/O hanging on Linux](https://forums.swift.org/t/subprocess-i-o-hanging-on-linux/78961)
**Author:** [@danpalmer](https://forums.swift.org/u/danpalmer)\ **Replies:** 7\ **Last updated:** [December 10, 2025, 3:15pm UTC](https://forums.swift.org/t/subprocess-i-o-hanging-on-linux/78961 "2025-12-10T15:15:12Z")
Hey folks, I've been testing some code that runs a subprocess and attempts to read stdout/stderr back into Swift asynchronously, but getting hangs 100% of the time under Linux. I've written up a bug report and example c… --- ## [Possible feature: inspect Task execution time](https://forums.swift.org/t/possible-feature-inspect-task-execution-time/83396)
**Author:** [@maartene](https://forums.swift.org/u/maartene)\ **Replies:** 10\ **Last updated:** [December 1, 2025, 8:58pm UTC](https://forums.swift.org/t/possible-feature-inspect-task-execution-time/83396 "2025-12-01T20:58:43Z")
Hi Swift Heroes! :superhero: I’m reaching out to get your thoughts on an idea we’re exploring: adding the ability to measure the actual time spent working on a Task. There’s already WIP on an experimental implementation,… --- ## [Crashing build when testing my app](https://forums.swift.org/t/crashing-build-when-testing-my-app/83422)
**Author:** [@jrodriguer](https://forums.swift.org/u/jrodriguer)\ **Replies:** 1\ **Last updated:** [November 26, 2025, 12:30pm UTC](https://forums.swift.org/t/crashing-build-when-testing-my-app/83422 "2025-11-26T12:30:29Z")
The Test target not build for not such file or directory: 'CoreGraphics'. Not sure why I get this error, but I configured the target without forgetting the variables BUNDLE\_LOADER with $(BUILT\_PRODUCTS\_DIR)/MyExistingAp… --- ## [addTeardownBlock completion assigned to the @MainActor](https://forums.swift.org/t/addteardownblock-completion-assigned-to-the-mainactor/83255)
**Author:** [@dataports](https://forums.swift.org/u/dataports)\ **Replies:** 1\ **Last updated:** [November 17, 2025, 9:06pm UTC](https://forums.swift.org/t/addteardownblock-completion-assigned-to-the-mainactor/83255 "2025-11-17T21:06:15Z")
Hi all, I’m midway through a Swift 6 migration and have been migrating some unit test files recently and have been struggling a bit with whather to use MainActor in unit tests as a means to isolate certain bits of code … --- ## [Potential issue for NS\_INLINE+ dispatch\_once on swift-corelibs-foundation](https://forums.swift.org/t/potential-issue-for-ns-inline-dispatch-once-on-swift-corelibs-foundation/70439)
**Author:** [@Kyle-Ye](https://forums.swift.org/u/Kyle-Ye)\ **Replies:** 5\ **Last updated:** [October 27, 2025, 4:51pm UTC](https://forums.swift.org/t/potential-issue-for-ns-inline-dispatch-once-on-swift-corelibs-foundation/70439 "2025-10-27T16:51:04Z")
Background static variables in the static function are shared by the same compile Unit, but not by different compile Units. static variables in normal functions share one copy. The NS\_INLINE is defined as follows #if … --- ## [XCTest: data race detected](https://forums.swift.org/t/xctest-data-race-detected/75322)
**Author:** [@andreabou](https://forums.swift.org/u/andreabou)\ **Replies:** 4\ **Last updated:** [September 22, 2025, 9:25am UTC](https://forums.swift.org/t/xctest-data-race-detected/75322 "2025-09-22T09:25:07Z")
Hello, The XCTest framework does not seem to be compliant with the Swift 6 concurrency model. See the example below: Test.swift: @globalActor actor TestActor: GlobalActor { static let shared: TestActor = .init() }… --- ## [Using the C library from Swift: thoughts](https://forums.swift.org/t/using-the-c-library-from-swift-thoughts/77648)
**Author:** [@al45tair](https://forums.swift.org/u/al45tair)\ **Replies:** 66\ **Last updated:** [August 29, 2025, 6:39pm UTC](https://forums.swift.org/t/using-the-c-library-from-swift-thoughts/77648 "2025-08-29T18:39:08Z")
There has been some discussion in the comments of this PR for adding FreeBSD support about the fact that it is presently abusing the Glibc module (which really should just be for systems that use Glibc, of which FreeBSD … --- ## [Pthread\_Jit in Foundation](https://forums.swift.org/t/pthread-jit-in-foundation/80421)
**Author:** [@Yuzutchi](https://forums.swift.org/u/Yuzutchi)\ **Replies:** 0\ **Last updated:** [June 11, 2025, 10:24pm UTC](https://forums.swift.org/t/pthread-jit-in-foundation/80421 "2025-06-11T22:24:41Z")
I'm trying to create a JIT Compiler in Swift and I've found that importing Foundation imports some but not all of the functionality of pthread.h in that regard. But strangely enough actually importing pthread will then … --- ## [How to build swift-corelibs-foundation?](https://forums.swift.org/t/how-to-build-swift-corelibs-foundation/79451)
**Author:** [@DarkDust](https://forums.swift.org/u/DarkDust)\ **Replies:** 7\ **Last updated:** [May 4, 2025, 11:20am UTC](https://forums.swift.org/t/how-to-build-swift-corelibs-foundation/79451 "2025-05-04T11:20:00Z")
I wanted to work on swift-corelibs-foundation but I found it to be a pretty frustrating experience. Building it on macOS doesn't work, so I tried to set up a Linux VM instead. The actual question I'm having is: is there… --- ## [How to build swift-corelibs-foundation on macOS?](https://forums.swift.org/t/how-to-build-swift-corelibs-foundation-on-macos/78754)
**Author:** [@DarkDust](https://forums.swift.org/u/DarkDust)\ **Replies:** 5\ **Last updated:** [March 24, 2025, 6:12pm UTC](https://forums.swift.org/t/how-to-build-swift-corelibs-foundation-on-macos/78754 "2025-03-24T18:12:09Z")
I wanted to compile swift-corelibs-foundation on macOS but so far hit lots of roadblocks. Is it really only supported on non-Darwin platforms? Can someone please guide me? macOS 15.3.2, Xcode 16.2. I've downloaded the m… --- ## [Text encoding problems on Linux and Windows](https://forums.swift.org/t/text-encoding-problems-on-linux-and-windows/78656)
**Author:** [@sspringer](https://forums.swift.org/u/sspringer)\ **Replies:** 1\ **Last updated:** [March 19, 2025, 3:48pm UTC](https://forums.swift.org/t/text-encoding-problems-on-linux-and-windows/78656 "2025-03-19T15:48:39Z")
There are major problems with text encodings on Linux and Windows see this Swift issue from end of December which seemingly have not been addressed so far (the issue still displays "triage needed"). The problems are with… --- ## [Global concurrency thread pool behavior differs between Android and Linux](https://forums.swift.org/t/global-concurrency-thread-pool-behavior-differs-between-android-and-linux/78432)
**Author:** [@orobio](https://forums.swift.org/u/orobio)\ **Replies:** 0\ **Last updated:** [March 11, 2025, 9:57am UTC](https://forums.swift.org/t/global-concurrency-thread-pool-behavior-differs-between-android-and-linux/78432 "2025-03-11T09:57:38Z")
We found that the behavior of the global concurrency thread pool differs between Android and Linux. On both, the thread pool starts out with a number of threads that corresponds with the number of cores the system has. H… --- ## [Swift Foundation Date Representation](https://forums.swift.org/t/swift-foundation-date-representation/77954)
**Author:** [@CrownedPhoenix](https://forums.swift.org/u/CrownedPhoenix)\ **Replies:** 28\ **Last updated:** [March 3, 2025, 8:12pm UTC](https://forums.swift.org/t/swift-foundation-date-representation/77954 "2025-03-03T20:12:37Z")
Can/Should Foundation.Date use a fixed-point representation? Why I Care Since the release of Swift 6, I've started running into round-trip equality issues with Foundation.Date through sqlite-nio and postgres-nio. Speci… --- ## [Any plans to merge \`Swift Collections\` and \`Swift Numerics\` into Swift core library?](https://forums.swift.org/t/any-plans-to-merge-swift-collections-and-swift-numerics-into-swift-core-library/77854)
**Author:** [@Gumichocopengin8](https://forums.swift.org/u/Gumichocopengin8)\ **Replies:** 29\ **Last updated:** [February 19, 2025, 9:12pm UTC](https://forums.swift.org/t/any-plans-to-merge-swift-collections-and-swift-numerics-into-swift-core-library/77854 "2025-02-19T21:12:03Z")
Swift Collections and Swift Numerics are great and commonly used, and libraries like them are usually in standard libraries in other programming languages. Any plan to merge these libraries into Swift core library? Any … --- ## [PythonKit in Swift](https://forums.swift.org/t/pythonkit-in-swift/77545)
**Author:** [@begginer](https://forums.swift.org/u/begginer)\ **Replies:** 0\ **Last updated:** [January 29, 2025, 5:27pm UTC](https://forums.swift.org/t/pythonkit-in-swift/77545 "2025-01-29T17:27:59Z")
Good afternoon, please help me with connecting PythonKit to Swift, I get the same error "PythonKit/PythonLibrary.swift:59: Fatal error: 'try!' expression unexpectedly raised an error: Python library not found. Set the PY… --- ## [Dispatch inactivity and Swift bootstrapping](https://forums.swift.org/t/dispatch-inactivity-and-swift-bootstrapping/76944)
**Author:** [@3405691582](https://forums.swift.org/u/3405691582)\ **Replies:** 2\ **Last updated:** [January 1, 2025, 4:58pm UTC](https://forums.swift.org/t/dispatch-inactivity-and-swift-bootstrapping/76944 "2025-01-01T16:58:00Z")
Swift ultimately requires a functional Swift toolchain to build the compiler. Even though there's a lot of the compiler still written in C++, it's a great milestone reached. But setting the minutiae of getting a bootstra… --- ## [Custom DispatchQueue using main thread](https://forums.swift.org/t/custom-dispatchqueue-using-main-thread/76554)
**Author:** [@piyush\_singh](https://forums.swift.org/u/piyush_singh)\ **Replies:** 9\ **Last updated:** [December 18, 2024, 9:14pm UTC](https://forums.swift.org/t/custom-dispatchqueue-using-main-thread/76554 "2024-12-18T21:14:44Z")
Today I found one custom serial DispatchQueue queue in our app using Thread 1 to execute its' work. The function had an assertion to make sure it wasn't executing on the main thread. The assertion failed. My question: … --- ## [GlobalActor and DispatchQueue pairing like @MainActor and DispatchQueue.main](https://forums.swift.org/t/globalactor-and-dispatchqueue-pairing-like-mainactor-and-dispatchqueue-main/76529)
**Author:** [@jubishop](https://forums.swift.org/u/jubishop)\ **Replies:** 17\ **Last updated:** [December 12, 2024, 7:11am UTC](https://forums.swift.org/t/globalactor-and-dispatchqueue-pairing-like-mainactor-and-dispatchqueue-main/76529 "2024-12-12T07:11:56Z")
Right now I can use @MainActor and DispatchQueue.main to effectively step into the @MainActor context, for example: @MainActor final class Example { var test = "hello" } var myExample = Example() now if I want to ch… --- ## [\[FOU\] Locale Components, Language, and Language Components](https://forums.swift.org/t/fou-locale-components-language-and-language-components/54084)
**Author:** [@tinaliu](https://forums.swift.org/u/tinaliu)\ **Replies:** 17\ **Last updated:** [November 19, 2024, 4:48pm UTC](https://forums.swift.org/t/fou-locale-components-language-and-language-components/54084 "2024-11-19T16:48:27Z")
Apple’s Foundation team is working on improving Locale to promote clear semantics and provide straightforward ways to modify and inspect locale information. We’d like to get your feedback on if you think this will improv… --- ## [Building CoreFoundation for Darwin Based OS's](https://forums.swift.org/t/building-corefoundation-for-darwin-based-oss/75378)
**Author:** [@csekel](https://forums.swift.org/u/csekel)\ **Replies:** 4\ **Last updated:** [October 16, 2024, 12:36am UTC](https://forums.swift.org/t/building-corefoundation-for-darwin-based-oss/75378 "2024-10-16T00:36:29Z")
Hi Dev's, I've been working with an open-source project(PureDarwin - yes, we're still around) I've seen here in this CoreFoundation that there was a possibility of building CoreFoundation as a Standalone framework. Thou… --- ## [Why is \`DateFormatter\` Sendable but \`ISO8601DateFormatter\` isn't](https://forums.swift.org/t/why-is-dateformatter-sendable-but-iso8601dateformatter-isnt/73919)
**Author:** [@Icodak](https://forums.swift.org/u/Icodak)\ **Replies:** 4\ **Last updated:** [August 13, 2024, 12:36am UTC](https://forums.swift.org/t/why-is-dateformatter-sendable-but-iso8601dateformatter-isnt/73919 "2024-08-13T00:36:06Z")
I installed the latest Xcode version 16 beta 5 to try to enable swift 6 on my project and one of the errors I got led me to discover that the ISO8601DateFormatter is explicitly written as non-Sendable when DateFormatter … --- ## [Foundation URL Improvements](https://forums.swift.org/t/foundation-url-improvements/54057)
**Author:** [@icharleshu](https://forums.swift.org/u/icharleshu)\ **Replies:** 138\ **Last updated:** [August 5, 2024, 11:51am UTC](https://forums.swift.org/t/foundation-url-improvements/54057 "2024-08-05T11:51:10Z")
Hi all, Apple’s Foundation team is working on some improvements to URL, focused on simple changes we can make to improve the ergonomics of using it. Given that this is such a widely used type in Swift, we’re interested i… [Next page](https://forums.swift.org/c/development/corelibs/8.md?page=1)