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Calling StoreKit Swift from C++
What is the most obvious method of calling StoreKit from C++. I'm getting blocked by the fact that most of the critical StoreKit calls are async and functions marked a sync don't show up in the swift header for me to call from C++ (at least as far as I can tell). I'm trying to call let result = try await Product.products(for:productIDs) or let result = try await product.purchase() And C++ can't even see any functions I wrap these in as far as I can tell because i have to make them async. What am I missing? I tried a lot of alternates, like wrapping in Task { let result = try await Product.products(for:productIDs) } and it gives me 'Passing closure as a sending parameter' errors. Also when I try to call the same above code it gives me 'initializtion of immutable value never used' errors and the variables never appear. Code: struct storeChooser { public var productIDs: [String] public function checkProduct1 { Task { let result = try await Product.products(for: productIDs) } The above gives the initialization of immutable value skipped, and when I create a @State var products Then I get the 'passing closure as a sending parameter' error when i try to run it in a task it appears if I could make the function async and call it from C++ and have it return nothing it may work, does anyone know how to get C++ to see an async function in the -Swift.h file?
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132
May ’25
Questions about calculate the square root using Accelerate
I am currently studying the Accelerate library by referring to Apple documentation. Here is the link to the referenced document: https://developer.apple.com/documentation/accelerate/veclib/vforce When I executed the sample code provided at the bottom of the document, I found a case where the results were different. let n = 10_000 let x = (0..<n).map { _ in Float.random(in: 1 ... 10_000) } let y = x.map { return sqrt($0) } and let y = [Float](unsafeUninitializedCapacity: n) { buffer, initializedCount in vForce.sqrt(x, result: &buffer) initializedCount = n } The code below is provided to observe the issue described above. import Accelerate Task { let n = 1//10_000 let x = (0..<n).map { _ in Float(6737.015)//Float.random(in: 1 ... 10_000) } let y = x.map { return sqrt($0) } try? await Task.sleep(nanoseconds: 1_000_000_000) let z = [Float](unsafeUninitializedCapacity: n) { buffer, initializedCount in vForce.sqrt(x, result: &buffer) initializedCount = n } } For a value of 6737.015 when calculating the square root: Using the sqrt(_:) function gives the result 82.07932, While using the vForce.sqrt(_:result:) function gives the result 82.07933. Using a calculator, the value comes out as 82.07932139, which shows that the result from vForce is incorrect. Could you explain the reason behind this difference?
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522
Jan ’25
Best practice: Use of enum without cases for static helper functions?
Hi all, In Swift, I often see static helper functions grouped in an enum without any cases, like this: enum StringUtils { static func camelCaseToSnakeCase(_ input: String) -> String { // implementation } } Since this enum has no cases, it cannot be instantiated – which is exactly the point. It’s meant to group related functionality without any stored state, and without the need for instantiation. This pattern avoids writing a struct with a private init() and makes the intent clearer: "This is just a static utility, not an object." You’ll often see this used for things like: AnalyticsEvents.track(_:) My question: Is this use of a case-less enum considered good practice in Swift when building static-only helpers? Or is there a better alternative for expressing intent and preventing instantiation? I’d appreciate any insight – especially if there’s official guidance or references from the Swift core team. Thanks!
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178
May ’25
Strange values written in loop
I don't understand what's happening when I save values via a loop. I initialize an array with default values, then run a loop to assign calculated values to it. In the middle of the loop, I print values, then print values again after the loop is over. The array values sometimes change, even though nothing has been written between print calls (when they change, the values are equal the last value in the array, index 49). I made a test file which writes four types of values to an array: (1) A new class instance, (2) Calculation, (3) Variable, (4) Hard-code. Saving the same value gives different results between the different write methods: import Foundation let numElements : Int = 50 class CustomType{ var x : Double var y : Double init(x: Double = 1.23, y: Double = 2.34) { self.x = x self.y = y } } // Try this four different ways var array1 = [CustomType](repeating:CustomType(), count:numElements) var array2 = [CustomType](repeating:CustomType(), count:numElements) var array3 = [CustomType](repeating:CustomType(), count:numElements) var array4 = [CustomType](repeating:CustomType(), count:numElements) // Checking that defaults were written print("Pre: Point 1: (\(array1[44].x),\(array1[44].y))") print("Pre: Point 2: (\(array2[44].x),\(array2[44].y))") print("Pre: Point 3: (\(array3[44].x),\(array3[44].y))") print("Pre: Point 4: (\(array4[44].x),\(array4[44].y))") // --- Fix 1: Problem goes away if I uncomment this: // array1[44]=CustomType() // array2[44]=CustomType() // array3[44]=CustomType() // array4[44]=CustomType() // --- Fix 2: Or if you swap these two lines for the following line: // let index = 44 // do { for index in 0..<numElements{ let rads = Double(index) * 2 * Double.pi/Double(numElements) let sinrads = sin(rads), cosrads = cos(rads) // Four different ways to save to arrays array1[index] = CustomType(x:sin(rads),y:cos(rads)) array2[index].x = sin(rads) array2[index].y = cos(rads) array3[index].x = sinrads array3[index].y = cosrads array4[index].x = -0.684547105928689 array4[index].y = 0.7289686274214113 if(index==44){ print("\n== Printing results mid-loop at index 44 ==") print("During: index: \(index), Calculated Rads: \(rads)") print("During: Calculated Vals: (\(sin(rads)),\(cos(rads)))") print("During: Stored 'let' Vals: (\(sinrads),\(cosrads))") print("During: Point 1: (\(array1[44].x),\(array1[44].y))") print("During: Point 2: (\(array2[44].x),\(array2[44].y))") print("During: Point 3: (\(array3[44].x),\(array3[44].y))") print("During: Point 4: (\(array4[44].x),\(array4[44].y))") } } print("\n== Printing the same results after the loop ==") print("Post: Point 1: (\(array1[44].x),\(array1[44].y))") print("Post: Point 2: (\(array2[44].x),\(array2[44].y))") print("Post: Point 3: (\(array3[44].x),\(array3[44].y))") print("Post: Point 4: (\(array4[44].x),\(array4[44].y))") print("\n== Reverse-calculating results from a correct array (array 1) to get the for loop index ==") print("reverse index calculation 01: \( (atan2(array1[ 1].x,array1[ 1].y) + Double.pi * 0) * Double(numElements)/(2*Double.pi) )") print("reverse index calculation 44: \( (atan2(array1[44].x,array1[44].y) + Double.pi * 2) * Double(numElements)/(2*Double.pi) )") print("reverse index calculation 45: \( (atan2(array1[45].x,array1[45].y) + Double.pi * 2) * Double(numElements)/(2*Double.pi) )") print("\n== Reverse-calculating results from an incorrect array (array 2) to get the for loop index ==") print("reverse index calculation 1: \( (atan2(array2[ 1].x,array2[ 1].y) + Double.pi * 2) * Double(numElements)/(2*Double.pi) )") print("reverse index calculation 44: \( (atan2(array2[44].x,array2[44].y) + Double.pi * 2) * Double(numElements)/(2*Double.pi) )") print("reverse index calculation 45: \( (atan2(array2[45].x,array2[45].y) + Double.pi * 2) * Double(numElements)/(2*Double.pi) )") Which gives the following output: Pre: Point 1: (1.23,2.34) Pre: Point 2: (1.23,2.34) Pre: Point 3: (1.23,2.34) Pre: Point 4: (1.23,2.34) == Printing results mid-loop at index 44 == During: index: 44, Calculated Rads: 5.529203070318036 During: Calculated Vals: (-0.684547105928689,0.7289686274214113) During: Stored 'let' Vals: (-0.684547105928689,0.7289686274214113) During: Point 1: (-0.684547105928689,0.7289686274214113) During: Point 2: (-0.684547105928689,0.7289686274214113) During: Point 3: (-0.684547105928689,0.7289686274214113) During: Point 4: (-0.684547105928689,0.7289686274214113) == Printing the same results after the loop == Post: Point 1: (-0.684547105928689,0.7289686274214113) Post: Point 2: (-0.12533323356430465,0.9921147013144778) Post: Point 3: (-0.12533323356430465,0.9921147013144778) Post: Point 4: (-0.684547105928689,0.7289686274214113) == Reverse-calculating results from a correct array (array 1) to get the for loop index == reverse index calculation 01: 1.0000000000000002 reverse index calculation 44: 43.99999999999999 reverse index calculation 45: 45.0 == Reverse-calculating results from an incorrect array (array 2) to get the for loop index == reverse index calculation 1: 49.0 reverse index calculation 44: 49.0 reverse index calculation 45: 49.0 Program ended with exit code: 0 Re-initializing the objects prior to the loop fixes the problem (see "Fix 1" in the comments), but the elements of the array are all initialized during creation and I don't understand why doing it a second time is helpful. The values should all be the same, am I missing something simple?
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512
Dec ’24
Can I use @_implementationOnly import in my Framework
We have FrameworkA which needs to use another FrameworkB internally to fetch a token. Now when I try to use this FrameworkA, we are seeing an issue with internal framework i.e. No such module 'FrameworkB'. But when I use @_implementationOnly import for the internal FrameworkB, I didn't see any issues. So just wanted to check If I can go ahead and use this @_implementationOnly import flag in Production?
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110
May ’25
indices(where:) Swift Playgrounds Issue: "Cannot call value of non-function type Range<Int>"
Hey there- I'm having a quite interesting bug on Swift Playgrounds. I am trying to run my app with this following code snippet which does not compile on Swift Playgrounds, yet compiles on XCode (note: this is a Swift Playground app) if #available(iOS 18.0, *) { //simple function to get the indices of other items that have the same date as the "date" variable let indices = data!.indices(where: { item in let sameMonth = Calendar.current.component(.month, from: item.time) == Calendar.current.component(.month, from: date) let sameYear = Calendar.current.component(.year, from: item.time) == Calendar.current.component(.year, from: date) let sameDay = Calendar.current.component(.day, from: item.time) == Calendar.current.component(.year, from: date) return sameDay && sameMonth && sameYear }) However, the indices(where:) codeblock seems to stop the app from compiling (ONLY on Swift Playgrounds - it works perfectly fine on XCode). I am getting the following error: Cannot call value of non-function type 'Range<Array<Int>.Index>' (aka 'Range<Int>') Please let me know if you have any insight regarding this issue. -ColoredOwl
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539
Jan ’25
Understanding an assertion failure in a crash log
Last night my iPhone game crashed while running in debug mode on my iPhone. I just plugged it into my Mac, and was able to find the ips file. The stack trace shows the function in my app where it crashed, and then a couple of frames in libswiftCore.dylib before an assertion failure. My question is - I've got absolutely no idea what the assertion failure actually was, all I have is... 0 libswiftCore.dylib 0x1921412a0 closure #1 in closure #1 in closure #1 in _assertionFailure(_:_:file:line:flags:) + 228 1 libswiftCore.dylib 0x192141178 closure #1 in closure #1 in _assertionFailure(_:_:file:line:flags:) + 327 2 libswiftCore.dylib 0x192140b4c _assertionFailure(_:_:file:line:flags:) + 183 3 MyGame.debug.dylib 0x104e52818 SentryBrain.takeTurn(actor:) + 1240 ... How do I figure out what the assertion failure was that triggered the crash? How do I figure out what line of code in takeTurn(...) triggered the failing assertion failure?
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112
Jun ’25
Using InlineArray on older OS versions
Hi, I’m trying to use the new InlineArray type, but noticed that it is unfortunately only available on macOS 26 and not on macOS 15 and others. As this is quite an essential type, I was wondering if this is intended or will this change in later beta’s? Not having it available on older Darwin platforms would severily limit it’s usage in the coming years. Thanks!
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121
Jun ’25
Swift 6 concurrency. Apple Watch App target and -disable-dynamic-actor-isolation.
I've got a watch app, still with storyboard, WKInterfaceController and WatchConnectivity. After updating it for swift 6 concurrency I thought I'd keep it for a little while without swift 6 concurrency dynamic runtime check. So I added -disable-dynamic-actor-isolation in OTHER_SWIFT_FLAGS, but it doesn't seem to have an effect for the Apple Watch target. Without manually marking callbacks where needed with @Sendable in dynamic checks seem to be in place. swiftc invocation is as (includes -disable-dynamic-actor-isolation): swiftc -module-name GeoCameraWatchApp -Onone -enforce-exclusivity\=checked ... GeoCameraWatchApp.SwiftFileList -DDEBUG -enable-bridging-pch -disable-dynamic-actor-isolation -D DEBUG -enable-experimental-feature DebugDescriptionMacro -sdk /Applications/Xcode.app/Contents/Developer/Platforms/WatchOS.platform/Developer/SDKs/WatchOS11.2.sdk -target arm64_32-apple-watchos7.0 -g -module-cache-path /Users/stand/Library/Developer/Xcode/DerivedData/ModuleCache.noindex -Xfrontend -serialize-debugging-options -enable-testing -index-store-path /Users/stand/Library/Developer/Xcode/DerivedData/speedo-almhjmryctkitceaufvkvhkkfvdw/Index.noindex/DataStore -enable-experimental-feature OpaqueTypeErasure -Xcc -D_LIBCPP_HARDENING_MODE\=_LIBCPP_HARDENING_MODE_DEBUG -swift-version 6 ... -disable-dynamic-actor-isolation flag seems to be working for the iOS targets, I believe. The flag is described here Am I missing something? Should the flag work for both iOS and Apple Watch targets?
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617
Jan ’25
Trailing closure bug?
i am trying to build my code and have ran into this error. "Trailing closure passed to parameter of type 'DispatchWorkItem' that does not accept a closure" i have been trying to figure it out for so long, and even ai cant figure it out. is this a bug, or am i missing some obvious way to fix this ? func loadUser(uid: String, completion: (() -&gt; Void)? = nil) { db.collection("users").document(uid).getDocument { [weak self] snapshot, error in guard let data = snapshot?.data(), error == nil else { completion?(); return } DispatchQueue.main.async { self?.currentUser = User( username: data["username"] as? String ?? "Learner", email: data["email"] as? String ?? "", profileImageName: "person.circle.fill", totalXP: data["totalXP"] as? Int ?? 0, currentStreak: data["currentStreak"] as? Int ?? 0, longestStreak: data["longestStreak"] as? Int ?? 0, level: data["level"] as? Int ?? 1, levelProgress: data["levelProgress"] as? Double ?? 0.0, xpToNextLevel: data["xpToNextLevel"] as? Int ?? 100, completedLessons: data["completedLessons"] as? [String] ?? [] ) self?.saveUser() completion?() } } }
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168
Jun ’25
Default Actor Isolation and foundational protocols
I've been testing my open source libraries with Swift 6.2 and the new Default Actor Isolation concurrency build setting set to MainActor (with Complete strict concurrency turned on). My library Destinations uses protocols extensively, often applying conformance to foundational Swift protocols like Hashable and Identifiable. Many of these basic protocols are not flagged as running on the @MainActor in Beta 1, leading to situations like this: Given this example code: public protocol Contentable: Identifiable { var id: UUID { get } } final class ContentModel: Contentable { let id: UUID = UUID() } I get the warning: Multiline Conformance of 'ContentModel' to protocol 'Contentable' crosses into main actor-isolated code and can cause data races; this is an error in the Swift 6 language mode The fix it suggests is to put a @MainActor before the Contentable protocol declaration in ContentModel, which seems to be a new attribute configuration in Swift 6.2. This solves the warning, but would create a lot of extra noise across the codebase. Was it an oversight or a temporary omission that protocols like Hashable and Identifiable do not run on @MainActor by default, or is there some other reason they are excluded? Considering how often protocols in our code may conform to foundational protocols like this, it seems at odds to the MainActor mode of the Default Actor Isolation setting given that it was created to make concurrency easier and less boilerplate to implement.
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186
Jun ’25
Tuple Comparision
I was trying to evaulate let myTuple = ("blue", false) let otherTuple = ("blue", true) if myTuple &lt; otherTuple { print("yes it evaluates") } Ans I got /tmp/S9jAk7P7KW/main.swift:5:12: error: binary operator '&lt;' cannot be applied to two '(String, Bool)' operands if myTuple &lt; otherTuple { My question is why there is no compile time issue in first place where the declaration is let myTuple = ("blue", false) ~~~~~~ something like above
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461
Jul ’25
AsyncStream does not cancel inner Task
AsyncStream { continuation in Task { let response = await getResponse() continuation.yield(response) continuation.finish() } } In this WWDC video https://developer.apple.com/videos/play/wwdc2025/231/ at 8:20 the presenter mentions that if the "Task gets cancelled, the Task inside the function will automatically get cancelled too". The documentation does not mention anything like this. From my own testing on iOS 18.5, this is not true.
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621
Jul ’25
Strange crash when using .values from @Published publisher
Given the below code with Swift 6 language mode, Xcode 16.2 If running with iOS 18+: the app crashes due to _dispatch_assert_queue_fail If running with iOS 17 and below: there is a warning: warning: data race detected: @MainActor function at Swift6Playground/PublishedValuesView.swift:12 was not called on the main thread Could anyone please help explain what's wrong here? import SwiftUI import Combine @MainActor class PublishedValuesViewModel: ObservableObject { @Published var count = 0 @Published var content: String = "NA" private var cancellables: Set<AnyCancellable> = [] func start() async { let publisher = $count .map { String(describing: $0) } .removeDuplicates() for await value in publisher.values { content = value } } } struct PublishedValuesView: View { @ObservedObject var viewModel: PublishedValuesViewModel var body: some View { Text("Published Values: \(viewModel.content)") .task { await viewModel.start() } } }
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583
Dec ’24
Structured concurrency + preconcurrency API (SFAuthorizationPluginView)
I'm having trouble dealing with concurrency with the SFAuthorizationPluginView. Does anybody know how this can be solved? https://developer.apple.com/documentation/securityinterface/sfauthorizationpluginview The crux of it is: If I inherit an object as part of an API, and the API is preconcurrency, and thus is nonisolated (but in reality is @MainActor), how do I return a @MainActor GUI element? https://developer.apple.com/documentation/securityinterface/sfauthorizationpluginview/firstresponder() The longer story: I made my view class inherit SFAuthorizationPluginView. The API is preconcurrency (but not marked as preconcurrency) I started using concurrency in my plugin to retrieve data over XPC. (https://developer.apple.com/documentation/xpc/xpcsession + https://developer.apple.com/documentation/swift/withcheckedthrowingcontinuation(isolation:function:_:)) Once I retrieve the data over XPC, I need to post it on GUI, hence I've set my view class as @MainActor in order to do the thread switch. Swift compiler keeps complaining: override func firstResponder() -&gt; NSResponder? { return usernameField } "Main actor-isolated property 'usernameField' can not be referenced from a nonisolated context; this is an error in the Swift 6 language mode" override func firstResponder() -&gt; NSResponder? { MainActor.assumeIsolated { return usernameField } } "Sending 'self' risks causing data races; this is an error in the Swift 6 language mode" I think fundamentally, the API is forcing me to give away a @MainActor variable through a nonisolated function, and there is no way to shut up the compiler. I've tried @preconcurrency and it has no effect as far as I can tell. I've also tried marking the function explicitly as nonisolated. The rest of the API are less problematic, but returning a GUI variable is exceptionally difficult.
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676
Jul ’25
Runtime race condition warning when calling PHPhotoLibrary.shared().performChanges async
I have enabled runtime concurrency warnings to check for future problems concerning concurrency: Build Setting / Other Swift Flags: -Xfrontend -warn-concurrency -Xfrontend -enable-actor-data-race-checks When trying to call the async form of PHPhotoLibrary.shared().performChanges{} I get the following runtime warning: warning: data race detected: @MainActor function at ... was not called on the main thread in the line containing performChanges. My sample code inside a default Xcode multi platform app template is as follows: import SwiftUI import Photos @MainActor class FotoChanger{     func addFotos() async throws{         await PHPhotoLibrary.requestAuthorization(for: .addOnly)         try! await PHPhotoLibrary.shared().performChanges{             let data = NSDataAsset(name: "Swift")!.data             let creationRequest = PHAssetCreationRequest.forAsset()             creationRequest.addResource(with: .photo, data: data, options: PHAssetResourceCreationOptions())         }     } } struct ContentView: View {     var body: some View {         ProgressView()             .task{                 try! await FotoChanger().addFotos()             }     } } You would have to have a Swift data asset inside the asset catalog to run the above code, but the error can even be recreated if the data is invalid. But what am I doing wrong? I have not found a way to run perform changes, the block or whatever causes the error on the main thread. PS: This is only test code to show the problem, don't mind the forced unwraps.
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2.3k
Dec ’24
Swift 6 crash calling requestAutomaticPassPresentationSuppression
I found a similar problem here https://developer.apple.com/forums/thread/764777 and I could solve my problem by wrapping the call to requestAutomaticPassPresentationSuppression in a call to DispatchQueue.global().async. But my question is if this is really how things should work. Even with strict concurrency warnings in Swift 6 I don't get any warnings. Just a runtime crash. How are we supposed to find these problems? Couldn't the compiler assist with a warning/error. Why does the compiler make the assumptions it does about the method that is declared like this: @available(iOS 9.0, *) open class func requestAutomaticPassPresentationSuppression(responseHandler: @escaping (PKAutomaticPassPresentationSuppressionResult) -> Void) -> PKSuppressionRequestToken Now that we have migrated to Swift 6 our code base contains a bunch of unknown places where it will crash as above.
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473
Feb ’25
Possible typo in concurrency diagram (WWDC25: Elevate an app with Swift concurrency)
Hello, While watching WWDC25: Code-along: Elevate an app with Swift concurrency at timestamp 25:48, I noticed something in the slide/diagram that might be incorrect. The diagram shows ExtractSticker twice, but based on the code context and spoken explanation, I think it was meant to be ExtractSticker and ExtractColor. Reasoning: The surrounding code and narration describe the use of async let and a Sendable Data object. From the flow, one task extracts a sticker while the other extracts a color, so it seems like the diagram is inconsistent. I do understand that with @concurrent, having two ExtractSticker operations on the same Data is technically possible (with two concurrent process executing their respective ExtractSticker) — but that would be a different meaning than what the talk was describing. Since concurrency is already a subtle and error-prone topic, I thought it was worth pointing this out. If I’m mistaken, I’d love clarification. Otherwise, this could be a small correction to keep things aligned and clearer for everyone. Minor point overall, but Swift 6’s concurrency model is doing a fantastic job at helping us write safer code—so thank you to the team for that! (Attaching screenshots for reference)
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1.8k
Aug ’25