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() } } }

I ran into a problem, I have a recursive function in which Data type objects are temporarily created, because of this, the memory expands until the entire recursion ends. It would just be fixed using autoreleasepool, but it can't be used with async await, and I really don't want to rewrite the code for callbacks. Is there any option to use autoreleasepool with async await functions? (I Googled one option, that the Task already contains its own autoreleasepool, and if you do something like that, it should work, but it doesn't, the memory is still growing) func autoreleasepool&lt;Result&gt;(_ perform: @escaping () async throws -&gt; Result) async throws -&gt; Result { try await Task { try await perform() }.value }

The following code works when compiling for macOS: print(NSMutableDictionary().isEqual(to: NSMutableDictionary())) but produces a compiler error when compiling for iOS: 'NSMutableDictionary' is not convertible to '[AnyHashable : Any]' NSDictionary.isEqual(to:) has the same signature on macOS and iOS. Why does this happen? Can I use NSDictionary.isEqual(_:) instead?

Why doesn’t deinit support async? At the end of a test, I want to wipe data from HealthKit, and it’s delete function is asynchronous.

I’m creating an app using SwiftUI, and I would like to incorporate a small Java codebase that I created for the Android version of the app. Is there a way to package the Java code to work on iOS and macOS

Hi the below array and code to output a list item works fine: var quotes = [ [ "quote": "I live you the more ...", "order": "1" ], [ "quote": "There is nothing permanent ...", "order": "2" ], [ "quote": "You cannot shake hands ...", "order": "3" ], [ "quote": "Lord, make me an instrument...", "order": "4" ] ] cell.textLabel?.text = quotes[indexPath.row]["quote"] However if I change the "order" values to be numbers rather than text like below then for the above line I get an error message in Xcode "No exact matches in call to subscript". Please could someone tell me how to make it work with the numbers stored as numbers? (I'm wondering if creating an any array type and using the .text function has caused a conflict but I can't find how to resolve) [ "quote": "I live you the more ...", "order": 1 ], [ "quote": "There is nothing permanent ...", "order": 2 ], [ "quote": "You cannot shake hands ...", "order": 3 ], [ "quote": "Lord, make me an instrument...", "order": 4 ] ] Thank you for any pointers :-)

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.

After switching our iOS app project from Swift 5 to Swift 6 and publishing an update, we started seeing a large number of crashes in Firebase Crashlytics. The crashes are triggered by NotificationCenter methods (post, addObserver, removeObserver) and show the following error: BUG IN CLIENT OF LIBDISPATCH: Assertion failed: Block was expected to execute on queue [com.apple.main-thread (0x1f9dc1580)] All scopes to related calls are already explicitly marked with @MainActor. This issue never occurred with Swift 5, but appeared immediately after moving to Swift 6. Has anyone else encountered this problem? Is there a known solution or workaround? Thanks in advance!

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?

According to the doc: The value returned is the same as the value returned in the kEventParamKeyCode when using Carbon Events. So where can I find kEventParamKeyCode?

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.

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!

Using the DebugDescription macro to display an optional value produces a “String interpolation produces a debug description for an optional value” build warning. For example: @DebugDescription struct MyType: CustomDebugStringConvertible { let optionalValue: String? public var debugDescription: String { "Value: \(optionalValue)" } } The DebugDescription macro does not allow (it is an error) "Value: \(String(describing: optionalValue))" or "Value: \(optionalValue ?? "nil")" because “Only references to stored properties are allowed.” Is there a way to reconcile these? I have a build log full of these warnings, obscuring real issues.

NSPredicate(format: "SELF MATCHES %@", "^[0-9A-Z]+$").evaluate(with: "126𝒥ℰℬℬ𝒢𝒦𝒮33") Returns true, and I don't know why. 𝒥ℰℬℬ𝒢𝒦𝒮 is not between 0-9 and A-Z, and why it returns true? How to avoid similar problem like this when using NSPredicate?

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?() } } }

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

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.

After swapping the -objectAtIndex: method using method_exchangeImplementations, it will cause continuous memory growth. Connect the iPhone and run the provided project. Continuously tap the iPhone screen. Observe Memory; it will keep growing. Sample code

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..&lt;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: &amp;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..&lt;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: &amp;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?

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.