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I am a Chinese student beginner ,do you have any advice for me to learn swift?I don't know how to start it.Please!🙏
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169
Apr ’25
Crash when Mutating Array of Tuples with String Property from Multiple Threads
Hi Apple Developer Community, I'm facing a crash when updating an array of tuples from both a background thread and the main thread simultaneously. Here's a simplified version of the code in a macOS app using AppKit: class ViewController: NSViewController { var mainthreadButton = NSButton(title: "test", target: self, action: nil) var numbers = Array(repeating: (dim: Int, key: String)(0, "default"), count: 1000) override func viewDidLoad() { super.viewDidLoad() view.addSubview(mainthreadButton) mainthreadButton.translatesAutoresizingMaskIntoConstraints = false mainthreadButton.centerXAnchor.constraint(equalTo: view.centerXAnchor).isActive = true mainthreadButton.centerYAnchor.constraint(equalTo: view.centerYAnchor).isActive = true mainthreadButton.widthAnchor.constraint(equalToConstant: 100).isActive = true mainthreadButton.heightAnchor.constraint(equalToConstant: 100).isActive = true mainthreadButton.target = self mainthreadButton.action = #selector(arraytest(_:)) } @objc func arraytest(_ sender: NSButton) { print("array update started") // Background update DispatchQueue.global().async { for i in 0..<1000 { self.numbers[i].dim = i } } // Main thread update var sum = 0 for i in 0..<1000 { numbers[i].dim = i + 1 sum += numbers[i].dim print("test \(sum)") } mainthreadButton.title = "test = \(sum)" } } This results in a crash with the following message: malloc: double free for ptr 0x136040c00 malloc: *** set a breakpoint in malloc_error_break to debug What's interesting: This crash only happens when the tuple contains a String ((dim: Int, key: String)) If I change the tuple type to use two Int values ((dim: Int, key: Int)), the crash does not occur My Questions: Why does mutating an array of tuples containing a String crash when accessed from multiple threads? Why is the crash avoided when the tuple contains only primitive types like Int? Is there an underlying memory management issue with value types containing reference types like String? Any explanation about this behavior and best practices for thread-safe mutation of such arrays would be much appreciated. Thanks in advance!
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135
Apr ’25
Actors with Combine publishers as properties.
Is it ok for an Actor type to have a Publisher as a property to let others observe changes over time? Or use the @Published property wrapper to achieve this? actor MyActor { var publisher = PassthroughSubject<Int, Never>() var data: Int { didSet { publisher.send(data) } } ... } // Usage var tasks = Set<AnyCancellable>() let actor = MyActor() Task { let publisher = await actor.publisher publisher.sink { print($0) }.store(in: &tasks) } This seems like this should be acceptable. I would expect a Publisher to be thread safe, and as long as the Output is a value type things should be fine. I have been getting random EXC_BAD_ACCESS errors when using this approach. But turning on the address sanitizer causes these crashes to go away. I know that isn't very specific but I wanted to start by seeing if this type of pattern is ok to do.
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2.7k
Apr ’25
Open any Swift view from C++
I've narrowed down my question after many rabbit holes - how can C++ code open any view in Swift. I can call functions in swift from C++ (works great), but not async or main actor (or actor at all) functions. And if I'm not mistaken all views are actors if not main actors? When calling from C+ I think its necessary that the first view be the main actor? I've implemented the code from the WWDC23 C++ interop video (Zoe's image picker) where I made a view in a struct, and just want to call it and let the view do the work. The compiler immediately gives me 'cannot expose main actors to C++'. If I'm not mistaken, doesn't this block the opening of any kind of swift view from C++? Hopefully I'm missing something obvious, which is likely :) In Zoe's code was his entry point into the program still Swift and not actually C++ app? Thanks! Thanks!
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129
May ’25
'init(coordinateRegion:interactionModes:showsUserLocation:userTrackingMode:annotationItems:annotationContent:)' was deprecated in iOS 17.0: Use Map initializers that t
I am currently encountering two deprecated errors in my code. Could someone please identify the issues with the code? Errors: 'init(coordinateRegion:interactionModes:showsUserLocation:userTrackingMode:annotationItems:annotationContent:)' was deprecated in iOS 17.0: Use Map initializers that take a MapContentBuilder instead. 'MapAnnotation' was deprecated in iOS 17.0: Use Annotation along with Map initializers that take a MapContentBuilder instead. Code: // MARK: - Stores Map (Dynamic) struct StoresMapView: View { @State private var storeLocations: [StoreLocation] = [] @State private var region = MKCoordinateRegion( center: CLLocationCoordinate2D(latitude: -31.95, longitude: 115.86), span: MKCoordinateSpan(latitudeDelta: 0.5, longitudeDelta: 0.5) ) var body: some View { Map(coordinateRegion: $region, interactionModes: .all, annotationItems: storeLocations) { store in MapAnnotation(coordinate: CLLocationCoordinate2D(latitude: store.latitude, longitude: store.longitude)) { VStack(spacing: 4) { Image(systemName: "leaf.circle.fill") .font(.title) .foregroundColor(.green) Text(store.name) .font(.caption) .fixedSize() } } } .onAppear(perform: loadStoreData) .navigationTitle("Store Locator") } private func loadStoreData() { guard let url = URL(string: "https://example.com/cop092/StoreLocations.json") else { return } URLSession.shared.dataTask(with: url) { data, _, _ in if let data = data, let decoded = try? JSONDecoder().decode([StoreLocation].self, from: data) { DispatchQueue.main.async { self.storeLocations = decoded if let first = decoded.first { self.region.center = CLLocationCoordinate2D(latitude: first.latitude, longitude: first.longitude) } } } }.resume() } }
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125
May ’25
Swift Concurrency: Calling @MainActor Function from Protocol Implementation in Swift 6
I have a Settings class that conform to the TestProtocol. From the function of the protocol I need to call the setString function and this function needs to be on the MainActor. Is there a way of make this work in Swift6, without making the protocol functions running on @MainActor The calls are as follows: class Settings: TestProtocol{ var value:String = "" @MainActor func setString( _ string:String ){ value = string } func passString(string: String) { Task{ await setString(string) } } } protocol TestProtocol{ func passString( string:String ) }
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177
May ’25
Issue with Swift 6 migration issues
We are migrating to swift 6 from swift 5 using Xcode 16.2. we are getting below errors in almost each of our source code files : Call to main actor-isolated initializer 'init(storyboard:bundle:)' in a synchronous non isolated context Main actor-isolated property 'delegate' can not be mutated from a nonisolated context Call to main actor-isolated instance method 'register(cell:)' in a synchronous nonisolated context Call to main actor-isolated instance method 'setup()' in a synchronous nonisolated context Few questions related to these compile errors. Some of our functions arguments have default value set but swift 6 does not allow to set any default values. This requires a lot of code changes throughout the project. This would be lot of source code re-write. Using annotations like @uncheck sendable , @Sendable on the class (Main actor) name, lot of functions within those classes , having inside some code which coming from other classes which also showing main thread issue even we using @uncheck sendable. There are so many compile errors, we are still seeing other than what we have listed here. Fixing these compile errors throughout our project, would be like a re-write of our whole application, which would take lot of time. In order for us to migrate efficiently, we have few questions where we need your help with. Below are the questions. Are there any ways we can bypass these errors using any keywords or any other way possible? Can Swift 5 and Swift 6 co-exist? so, we can slowly migrate over a period of time.
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177
Jun ’25
Image Not Displaying on Some Devices – Same Code, Inconsistent Behavior
I'm encountering an issue where certain images are not displaying on some iOS devices, while the same code works perfectly on others. There’s no error or crash — just some images fail to load or display. I've confirmed the image URLs and formats are correct. Has anyone faced a similar issue or could suggest what might be causing this inconsistent behavior? Thanks in advance!
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87
Jun ’25
Snapshot error
Hey everyone, I have a problem with an app im creating. The code doesn't have any errors but the console has this that pops up: Snapshot request 0x1054191d0 complete with error: <NSError: 0x10541a970; domain: FBSSceneSnapshotErrorDomain; code: 4; "an unrelated condition or state was not satisfied"> { NSLocalizedDescription = an error occurred during a scene snapshotting operation; }
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114
Jun ’25
Undefined symbol: _main Error
I’ve been struggling with this issue for a long time. When I try to archive my app to submit it to the App Store, I encounter two errors: Linker command failed with exit code 1 (use -v to see invocation) Linker command failed with exit code 1 (use -v to see invocation)
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119
Jun ’25
Swift/C++ interoperability issue in std::string
In scope of one of our project we've faced an issue with constant crashes when integrating C++ library in Swift code using Swift/C++ interoperability. Investigating the root causes of the issue we've discovered that with new version of Swift bug was introduced. Long story short: for strings bigger than 27 symbols memory is feed incorrectly that causes the crashes. By creating this post I wanted to draw community's attention to the problem and promote it to be solved quicker as for now it is not addressed.
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538
Jul ’25
Swift OpenAPI Generator Error
PLATFORM AND VERSION iOS Development environment: Xcode 26, macOS 26 Run-time configuration: iOS 18 and up DESCRIPTION OF PROBLEM I am on the beta version of os 26 for both Xcode and macOS. When I try to run my project, which has the Swift OpenAPI Generator from apple, it gives the error "unsupported configuration: the aggregate target 'OpenAPIGenerator' has package dependencies, but targets that build for different platforms depend on it" STEPS TO REPRODUCE Install macOS 26 and Xcode 26 and try running an iOS app built for iOS 18.0 and up wit the OpenAPIGenerator package on a physical iPhone running iOS 26
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368
Jul ’25
Load bundle resources in UI Tests
I want to load images from my bundle, which works fine when running the main app. However this does not work when running UI Tests. I read that the test bundle is not the main bundle when running tests. I try loading the bundle via this snippet: let bundle = Bundle(for: Frames_HoerspielUITests.self) This is my test class wrapped these the canImport statements so it can be added to the main app target and used for getting the correct bundle: #if canImport(XCTest) import XCTest final class Frames_HoerspielUITests: XCTestCase { override func setUpWithError() throws { continueAfterFailure = false } override func tearDownWithError() throws { } @MainActor func testExample() throws { let app = XCUIApplication() app.launch() } @MainActor func testLaunchPerformance() throws { measure(metrics: [XCTApplicationLaunchMetric()]) { XCUIApplication().launch() } } } #else final class Frames_HoerspielUITests { } #endif However while this works when running the main app, it still fails in the UI tests. It is a SwiftUI only app. and I can't add the images to the asset catalog because they are referenced from another location. Any ideas? Thank you
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329
Jul ’25
Error about "swift for windows" at windows11
谁能告诉我为什么? “[正在运行] swift ”d:\vscode object\swift object\ceshi.swift” JIT 会话错误:未找到符号:[ $ss 27_allocateUninitializedArrayySayxG_BptBwlFyp_Tg5 ] 未能具体化符号: { (main, { main, $sSa 12_endMutationyyF, $ss 5print_9separator10terminatoryypd_S2StFfA0_, $ss 5print_9separator10terminatoryypd_S2StFfA1_, $ss 27_finalizeUninitializedArrayySayxGABnlF }) } [完成] 在 0.47 秒内退出并带有 code=4294967295” 当“Swift for Windows”在 VSCode for Windows 上运行时。 路径为 true,“Package-swift-lsp: Path”为 true。 谁能告诉我为什么?
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843
Jul ’25
Module compiled with Swift 6.0.3 cannot be imported by the Swift 6.1 compiler
Module compiled with Swift 6.0.3 cannot be imported by the Swift 6.1 compiler: /private/var/tmp/_bazel_xx/8b7c61ad484d9da1bf94a11f12ae6ffd/rules_xcodeproj.noindex/build_output_base/execroot/main/CustomModules/BIYThred/CocoaLumberjack/framework/CocoaLumberjack.framework/Modules/CocoaLumberjack.swiftmodule/arm64-apple-ios.swiftmodule
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751
Jul ’25
Customization in Swift ArgumentParser's help command and error output
Hello I want to implement customisation to swift argumentparser, Here are following changes want to do it in my cli changing default footer present in help command output currently help command output coming like this OVERVIEW: clisample USAGE: clisample <subcommand> OPTIONS: --version show the version. -h, --help show the help. SUBCOMMANDS: logs (default) Export logs for clisample processes. See 'clisample --help' for more information.' so instead of See 'clisample --help' for more information.' I want my own string For more details, run 'clisample help <subcommand>' customise error string getting from validation error Error: Missing value for '-t <time>' Help: -t <time> Time window (e.g. 10h, 30m, 2d). Usage: clisample logs --time <time> See 'clisample logs --help' for more information. so I want error output with example and customised footer, like this Error: Missing value for '-t <time>' Help: -t <time> Time window (e.g. 10h, 30m, 2d). Usage: clisample logs --time <time> Example: clisample logs -t 5m For more details, run 'clisample help <subcommand>' Is this changes possible from anyway?
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544
Sep ’25