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

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

I'm trying to use FormatStyle from Foundation to format numbers when printing a vector structure. See code below. import Foundation struct Vector<T> { var values: [T] subscript(item: Int) -> T { get { values[item] } set { values[item] = newValue } } } extension Vector: CustomStringConvertible { var description: String { var desc = "( " desc += values.map { "\($0)" }.joined(separator: " ") desc += " )" return desc } } extension Vector { func formatted<F: FormatStyle>(_ style: F) -> String where F.FormatInput == T, F.FormatOutput == String { var desc = "( " desc += values.map { style.format($0) }.joined(separator: " ") desc += " )" return desc } } In the example below, the vector contains a mix of integer and float literals. The result is a vector with a type of Vector<Double>. Since the values of the vector are inferred as Double then I expect the print output to display as decimal numbers. However, the .number formatted output seems to ignore the vector type and print the values as a mix of integers and decimals. This is fixed by explicitly providing a format style with a fraction length. So why is the .formatted(.number) method ignoring the vector type T which is Double in this example? let vec = Vector(values: [-2, 5.5, 100, 19, 4, 8.37]) print(vec) print(vec.formatted(.number)) print(vec.formatted(.number.precision(.fractionLength(1...)))) ( -2.0 5.5 100.0 19.0 4.0 8.37 ) // correct output that uses all Double types ( -2 5.5 100 19 4 8.37 ) // wrong output that uses Int and Double types ( -2.0 5.5 100.0 19.0 4.0 8.37 ) // correct output that uses all Double types

Hello, I was hoping to clarify my understanding of the use of for await with an AsyncStream. My use case is, I'd like to yield async closures to the stream's continuation, with the idea that, when I use for await with the stream to process and execute the closures, it would only continue on to the following closure once the current closure has been run to completion. At a high level, I am trying to implement in-order execution of async closures in the context of re-entrancy. An example of asynchronous work I want to execute is a network call that should write to a database: func syncWithRemote() async -> Void { let data = await fetchDataFromNetwork() await writeToLocalDatabase(data) } For the sake of example, I'll call the intended manager of closure submission SingleOperationRunner. where, at a use site such as this, my desired outcome is that call 1 of syncWithRemote() is always completed before call 2 of it: let singleOperationRunner = SingleOperationRunner(priority: nil) singleOperationRunner.run { syncWithRemote() } singleOperationRunner.run { syncWithRemote() } My sketch implementation looks like this: public final class SingleOperationRunner { private let continuation: AsyncStream<() async -> Void>.Continuation public init(priority: TaskPriority?) { let (stream, continuation) = AsyncStream.makeStream(of: (() async -> Void).self) self.continuation = continuation Task.detached(priority: priority) { // Will this loop only continue when the `await operation()` completes? for await operation in stream { await operation() } } } public func run(operation: @escaping () async -> Void) { continuation.yield(operation) } deinit { continuation.finish() } } The resources I've found are https://developer.apple.com/videos/play/wwdc2022-110351/?time=1445 and https://forums.swift.org/t/swift-async-func-to-run-sequentially/60939/2 but do not think I have fully put the pieces together, so would appreciate any help!

I am writing a SPM based project for MacOS. In this project? I need to access MacOS Keychain. I am write a swift test built by SPM testTarget(). I can see it generates a bundle ./.build/x86_64-apple-macosx/debug/MyProjectTests.xctest with an executable: % file ./.build/x86_64-apple-macosx/debug/MyProjectPackageTests.xctest/Contents/MacOS/MyProjectPackageTests ./.build/x86_64-apple-macosx/debug/MyProjectPackageTests.xctest/Contents/MacOS/MyProjectPackageTests: Mach-O 64-bit bundle x86_64 This bundle file cannot be executed. How can I execute its tests? I tried with xcodebuild test-without-building -xctestrun ./.build/x86_64-apple-macosx/debug/MyProjectPackageTests.xctest -destination 'platform=macOS' without any chance. Obviously the next question is can I 'simply' add entitlement to this bundle with codesign to fix my enttilement error. My error when running the test is A required entitlement isn't present.

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() } } }

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)

Hello, I have a json array showing in Xcode debugger (from the line "print(dataString)"): Optional("[{\"id\":\"8e8tfdcssu4u2hn7a71tkveahjhn8xghqcfkwf1bzvtrw5nu0b89w\",\"name\":\"Ameliana\",\"country\":\"France\",\"type\":\"Private\\/Corporate\",\"overallrecsit\":\"Positive\",\"dlastupd\":\"1741351633\",\"doverallrecsit\":\"1546848000\"},{\"id\":\"z69718a1a5z2y5czkwrhr1u37h7h768v05qr3pf1fegh4r4yrt5a68\",\"name\":\"Timberland\",\"country\":\"Switzerland\",\"type\":\"Charter\",\"overallrecsit\":\"Negative\",\"dlastupd\":\"1741351615\",\"doverallrecsit\":\"1740434582\"}, But my JSON decoder is throwing the catch error "Error in JSON parsing" This is the code: super.viewDidLoad() let urlString = "https://www.pilotjobsnetwork.com/service_ios.php" let url = URL(string: urlString) guard url != nil else { return } let session = URLSession.shared let dataTask = session.dataTask(with: url!) { (data, response, error) in var dataString = String(data: data!, encoding: String.Encoding.utf8) print(dataString) if error == nil &amp;&amp; data != nil { // Parse JSON let decoder = JSONDecoder() do { let newsFeed = try decoder.decode(NewsFeed.self, from: data!) print(newsFeed) print(error) } catch{ print("Error in JSON parsing") } } } // Make the API Call dataTask.resume() } And this is my Codable file NewsFeed.swift: struct NewsFeed: Codable { var id: String var name: String var country: String var type: String var overallrecsit: String var dlastupd: String var doverallrecsit: String } Please do you know why the parsing may be failing? Is it significant that in the debugging window the JSON is displaying backslashes before the quotation marks? Thank you for any pointers :-)

I’m trying to create a property wrapper that that can manage shared state across any context, which can get notified if changes happen from somewhere else. I'm using mutex, and getting and setting values works great. However, I can't find a way to create an observer pattern that the property wrappers can use. The problem is that I can’t trigger a notification from a different thread/context, and have that notification get called on the correct thread of the parent object that the property wrapper is used within. I would like the property wrapper to work from anywhere: a SwiftUI view, an actor, or from a class that is created in the background. The notification preferably would get called synchronously if triggered from the same thread or actor, or otherwise asynchronously. I don’t have to worry about race conditions from the notification because the state only needs to reach eventuall consistency. Here's the simplified pseudo code of what I'm trying to accomplish: // A single source of truth storage container. final class MemoryShared<Value>: Sendable { let state = Mutex<Value>(0) func withLock(_ action: (inout Value) -> Void) { state.withLock(action) notifyObservers() } func get() -> Value func notifyObservers() func addObserver() } // Some shared state used across the app static let globalCount = MemoryShared<Int>(0) // A property wrapper to access the shared state and receive changes @propertyWrapper struct SharedState<Value> { public var wrappedValue: T { get { state.get() } nonmutating set { // Can't set directly } } var publisher: Publisher {} init(state: MemoryShared) { // ... } } // I'd like to use it in multiple places: @Observable class MyObservable { @SharedState(globalCount) var count: Int } actor MyBackgroundActor { @SharedState(globalCount) var count: Int } @MainActor struct MyView: View { @SharedState(globalCount) var count: Int } What I’ve Tried All of the examples below are using the property wrapper within a @MainActor class. However the same issue happens no matter what context I use the wrapper in: The notification callback is never called on the context the property wrapper was created with. I’ve tried using @isolated(any) to capture the context of the wrapper and save it to be called within the state in with unchecked sendable, which doesn’t work: final class MemoryShared<Value: Sendable>: Sendable { // Stores the callback for later. public func subscribe(callback: @escaping @isolated(any) (Value) -> Void) -> Subscription } @propertyWrapper struct SharedState<Value> { init(state: MemoryShared<Value>) { MainActor.assertIsolated() // Works! state.subscribe { MainActor.assertIsolated() // Fails self.publisher.send() } } } I’ve tried capturing the isolation within a task with AsyncStream. This actually compiles with no sendable issues, but still fails: @propertyWrapper struct SharedState<Value> { init(isolation: isolated (any Actor)? = #isolation, state: MemoryShared<Value>) { let (taskStream, continuation) = AsyncStream<Value>.makeStream() // The shared state sends new values to the continuation. subscription = state.subscribe(continuation: continuation) MainActor.assertIsolated() // Works! let task = Task { _ = isolation for await value in taskStream { _ = isolation MainActor.assertIsolated() // Fails } } } } I’ve tried using multiple combine subjects and publishers: final class MemoryShared<Value: Sendable>: Sendable { let subject: PassthroughSubject<T, Never> // ... var publisher: Publisher {} // ... } @propertyWrapper final class SharedState<Value> { var localSubject: Subject init(state: MemoryShared<Value>) { MainActor.assertIsolated() // Works! handle = localSubject.sink { MainActor.assertIsolated() // Fails } stateHandle = state.publisher.subscribe(localSubject) } } I’ve also tried: Using NotificationCenter Making the property wrapper a class Using NSKeyValueObserving Using a box class that is stored within the wrapper. Using @_inheritActorContext. All of these don’t work, because the event is never called from the thread the property wrapper resides in. Is it possible at all to create an observation system that notifies the observer from the same context as where the observer was created? Any help would be greatly appreciated!

Hello, Please see the test project at https://we.tl/t-aWAu7kk9lD I have a json array showing in Xcode debugger (from the line "print(dataString)"): Optional("[{\"id\":\"8e8tcssu4u2hn7a71tkveahjhn8xghqcfkwf1bzvtrw5nu0b89w\",\"name\":\"Test name 0\",\"country\":\"Test country 0\",\"type\":\"Test type 0\",\"situation\":\"Test situation 0\",\"timestamp\":\"1546848000\"},{\"id\":\"z69718a1a5z2y5czkwrhr1u37h7h768v05qr3pf1h4r4yrt5a68\",\"name\":\"Test name 1\",\"country\":\"Test country 1\",\"type\":\"Test type 1\",\"situation\":\"Test situation 1\",\"timestamp\":\"1741351615\"},{\"id\":\"fh974sv586nhyysbhg5nak444968h7hgcgh6yw0usbvcz9b0h69\",\"name\":\"Test name 2\",\"country\":\"Test country 2\",\"type\":\"Test type 2\",\"situation\":\"Test situation 2\",\"timestamp\":\"1741351603\"},{\"id\":\"347272052385993\",\"name\":\"Test name 3\",\"country\":\"Test country 3\",\"type\":\"Test type 3\",\"situation\":\"Test situation 3\",\"timestamp\":\"1741351557\"}]") But my JSON decoder is throwing a catch error Line 57, Error in JSON parsing typeMismatch(Swift.Dictionary<Swift.String, Any>, Swift.DecodingError.Context(codingPath: [], debugDescription: "Expected to decode Dictionary<String, Any> but found an array instead.", underlyingError: nil)) This is the code: let urlString = "https://www.notafunnyname.com/jsonmockup.php" let url = URL(string: urlString) guard url != nil else { return } let session = URLSession.shared let dataTask = session.dataTask(with: url!) { (data, response, error) in var dataString = String(data: data!, encoding: String.Encoding.utf8) print(dataString) if error == nil && data != nil { // Parse JSON let decoder = JSONDecoder() do { let newsFeed = try decoder.decode(NewsFeed.self, from: data!) print("line 51") print(newsFeed) print(error) } catch{ print("Line 57, Error in JSON parsing") print(error) } } } // Make the API Call dataTask.resume() } And this is my Codable file NewsFeed.swift: struct NewsFeed: Codable { var id: String var name: String var country: String var type: String var situation: String var timestamp: String } Please do you know how to resolve the typeMismatch error?

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 }

Is there any way to retrieve the memory pressure percentage using native libraries? When I run the memory-pressure command, I can see the percentage of free memory, but I’d like to retrieve the same information using a native library.

I get this red warning in Xcode every time my app is syncing to the iCloud. My model has only basic types and enum that conform to Codable so i'm not sure what is the problem. App is working well, synchronization works. But the warning doesn't look good. Maybe someone has idea how to debug it.

Undefined symbols for architecture arm64: "_swift_coroFrameAlloc", referenced from: NvMobileCore.Constraint.isActive.modify : Swift.Bool in NvMobileCore[5] NvMobileCore.Constraint.isActive.modify : Swift.Bool in NvMobileCore[5] NvMobileCore.NvMobileCoreManager.delegate.modify : NvMobileCore.NvPublicInterface? in NvMobileCore[53] NvMobileCore.NvMobileCoreManager.delegate.modify : NvMobileCore.NvPublicInterface? in NvMobileCore[53] NvMobileCore.NvMobileCoreManager.language.modify : Swift.String in NvMobileCore[53] NvMobileCore.NvMobileCoreManager.language.modify : Swift.String in NvMobileCore[53] ld: symbol(s) not found for architecture arm64 clang: error: linker command failed with exit code 1 (use -v to see invocation)

var testTwo: Double = 0 testDouble = 80 testTwo = 200 var testThree: Int = 0 testThree = Int(testTwo/testDouble) var testDate: Date = .now var dateComponent = DateComponents() dateComponent.day = testThree var newDate: Date = Calendar.current.date(byAdding: dateComponentwith a thread error , to: testDate)! This code works in a playground. However, when I try to use it in Xcode for my app it fails with the following error: Thread 1: Fatal error: Double value cannot be converted to Int because it is either infinite or NaN I printed the value being converted to Int and it was not NAN or infinite.

Title Why doesn’t this async function see external changes to an inout Bool in Release builds (but works in Debug)? Body I have a small helper function that waits for a Bool flag to become true with a timeout: public func test(binding value: inout Bool, timeout maximum: Int) async throws { var count = 0 while value == false { count += 1 try await Task.sleep(nanoseconds: 0_100_000_000) if value == true { return } if count > (maximum * 10) { return } } } I call like this: var isVPNConnected = false adapter.start(tunnelConfiguration: tunnelConfiguration) { [weak self] adapterError in guard let self = self else { return } if let adapterError = adapterError { } else { isVPNConnected = true } completionHandler(adapterError) } try await waitUntilTrue(binding: &isVPNConnected, timeout: 10) What I expect: test should keep looping until flag becomes true (or the timeout is hit). When the second task sets flag = true, the first task should see that change and return. What actually happens: In Debug builds this behaves as expected: when the second task sets flag = true, the loop inside test eventually exits. In Release builds the function often never sees the change and gets stuck until the timeout (or forever, depending on the code). It looks like the while value == false condition is using some cached value and never observes the external write. So my questions are: Is the compiler allowed to assume that value (the inout Bool) does not change inside the loop, even though there are await suspension points and another task is mutating the same variable? Is this behavior officially “undefined” because I’m sharing a plain Bool across tasks without any synchronization (actors / locks / atomics), so the debug build just happens to work? What is the correct / idiomatic way in Swift concurrency to implement this kind of “wait until flag becomes true with timeout” pattern? Should I avoid inout here completely and use some other primitive (e.g. AsyncStream, CheckedContinuation, Actor, ManagedAtomic, etc.)? Is there any way to force the compiler to re-read the Bool from memory each iteration, or is that the wrong way to think about it? Environment (if it matters): Swift: [fill in your Swift version] Xcode: [fill in your Xcode version] Target: iOS / macOS [fill in as needed] Optimization: default Debug vs. Release settings I’d like to understand why Debug vs Release behaves differently here, and what the recommended design is for this kind of async waiting logic in Swift.

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!

I tried to build the project with Xcode 16.3 and I initially got an error that TARGET_IPHONE_SIMULATOR does not exist, then I changed this flag to TARGET_OS_SIMULATOR, but it did not solve the problem

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?

Hi, I'm trying to add Swift code to my Obj-C project. I've gone through all the tutorials and troubleshooting advice I can find online, no dice. I would appreciate any help, thank you so much in advance. I add a new swift file to my Obj-C project XCode offers to create a bridging header file for me, yes please New .swift file and .h file are added to my project no problem Header file shows up in build settings no problem I add a new class to my new swift file ("@objc class HelloPrinter: NSObject") When I build the app, nothing is generated in the bridging header file and the class is obviously inaccessible to my obj-c code Is this supposed to work? My understanding is that it's supposed to work. Somewhat concerning is the text that XCode puts in the bridging header file when it's created: "Use this file to import your target's public headers that you would like to expose to Swift." I don't want to use this bridging header file for anything. I want XCode to GENERATE STUFF in the bridging file. I also don't want to expose anything to Swift. I want the opposite to happen. So I don't get this text at all. Thanks in advance again.