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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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92
Apr ’25
SwiftData and 'NSKeyedUnarchiveFromData' should not be used to for un-archiving and will be removed in a future release
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.
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892
Dec ’24
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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116
May ’25
Common blocks in Swift?
I am porting an old app from ObjC. The app uses many defined constants such as: #define COM_OFFSET 12.5 and many variables that are read and/or written throughout the App, such as: PCDate* Dates[367]; @class PCMainView; PCMainView* MainView; in one file called "PCCommon.h" How do I duplicate this function in Swift? I have looked around and have found no help. Thanks in advance.
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436
Dec ’24
Alternative to CoreTelephony for Accessing Cellular Network Information in Private iOS App
Hello, I am developing a private internal Flutter app for our customer, which will not be published on the Apple Store. One of the key features of this app is to collect RF strength metrics to share user experience with the network. For Android, we successfully implemented the required functionality and are able to collect the following metrics: Signal strength level (0-4) Signal strength in dBm RSSI RSRQ Cell ID Location Area Code Carrier name Mobile country code Mobile network code Radio access technology Connection status Duplex mode However, for iOS, we are facing challenges with CoreTelephony, which is not returning the necessary data. We are aware that CoreTelephony is deprecated and are looking for alternatives. We noticed that a lot of the information we need is available via FTMInternal-4. Is there a way to access this data for a private app? Are there any other recommended approaches or frameworks that can be used to gather cellular network information on iOS for an app that won't be distributed via the Apple Store? my swift code import Foundation import CoreTelephony class RfSignalStrengthImpl: RfSignalStrengthApi { func getCellularSignalStrength(completion: @escaping (Result<CellularSignalStrength, Error>) -> Void) { let networkInfo = CTTelephonyNetworkInfo() guard let carrier = networkInfo.serviceSubscriberCellularProviders?.values.first else { completion(.failure(NSError(domain: "com.xxxx.yyyy", code: 0, userInfo: [NSLocalizedDescriptionKey: "Carrier not found"]))) return } let carrierName = carrier.carrierName ?? "Unknown" let mobileCountryCode = carrier.mobileCountryCode ?? "Unknown" let mobileNetworkCode = carrier.mobileNetworkCode ?? "Unknown" let radioAccessTechnology = networkInfo.serviceCurrentRadioAccessTechnology?.values.first ?? "Unknown" var connectionStatus = "Unknown" ... ... } Thank you for your assistance.
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1.7k
Jun ’25
Memory leak and a crash when swizzling NSURLRequest initialiser
When swizzling NSURLRequest initialiser and returning a mutable copy, the original instance does not get deallocated and eventually gets leaked and a crash follows after that. Here's the swizzling setup: static func swizzleInit() { let initSel = NSSelectorFromString("initWithURL:cachePolicy:timeoutInterval:") guard let initMethod = class_getInstanceMethod(NSClassFromString("NSURLRequest"), initSel) else { return } let origInitImp = method_getImplementation(initMethod) let block: @convention(block) (AnyObject, Any, NSURLRequest.CachePolicy, TimeInterval) -> NSURLRequest = { _self, url, policy, interval in typealias OrigInit = @convention(c) (AnyObject, Selector, Any, NSURLRequest.CachePolicy, TimeInterval) -> NSURLRequest let origFunc = unsafeBitCast(origInitImp, to: OrigInit.self) let request = origFunc(_self, initSel, url, policy, interval) return request.tagged() } let newImplementation = imp_implementationWithBlock(block as Any) method_setImplementation(initMethod, newImplementation) } // create a mutable copy if needed and add a header private func tagged() -> NSURLRequest { guard let mutableRequest = self as? NSMutableURLRequest ?? self.mutableCopy() as? NSMutableURLRequest else { return self } mutableRequest.setValue("test", forHTTPHeaderField: "test") return mutableRequest } Then, we have a few test cases: // memory leak and crash func testSwizzleNSURLRequestInit() { let request = NSURLRequest(url: URL(string: "https://example.com")!) XCTAssertEqual(request.value(forHTTPHeaderField: "test"), "test") } // no crash, as the request is mutable, so no copy is created func testSwizzleNSURLRequestInit2() { let request = URLRequest(url: URL(string: "https://example.com")!) XCTAssertEqual(request.value(forHTTPHeaderField: "test"), "test") } // no crash, as the request is mutable, so no copy is created func testSwizzleNSURLRequestInit3() { let request = NSMutableURLRequest(url: URL(string: "https://example.com")!) XCTAssertEqual(request.value(forHTTPHeaderField: "test"), "test") } // no crash, as the new instance does not get deallocated // when the test method completes (?) var request: NSURLRequest? func testSwizzleNSURLRequestInit4() { request = NSURLRequest(url: URL(string: "https://example.com")!) XCTAssertEqual(request?.value(forHTTPHeaderField: "test"), "test") } It appears a memory leak occurs only when any other instance except for the original one is being returned from the initialiser. Is there a workaround to prevent the leak, while allowing for modifications of all requests?
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572
Nov ’24
'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() } }
1
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99
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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144
May ’25
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?
2
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99
May ’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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155
Jun ’25
C++ and Swift in Xcode 16 broke my audio unit
I'm developing an audio unit for use on iOS. The AUv3 worked fine with xcode 15.X and swift 5.X. I recently tried to submit an update to my plug-in but Apple refused submission because my Xcode was not the latest. Now that I'm on Xcode 16.4 I can't get my project to compile, even when following all of the same previous steps. As one example of a change, Xcode doesn't appear to include the “C++ and Objective-C interoperability” build setting that it used to. This setting is noted in the Swift documentation and I used to need it, https://www.swift.org/documentation/cxx-interop/project-build-setup/#mixing-swift-and-c-using-xcode Currently my C++ code can't see anything from Swift, and I get a "Use of undeclared identifier 'project_name'". I've selected Switch support for version 5.0 in an attempt to minimize changes from Apple. My process is I generate an Xcode project file from my audio plugin support, JUCE. Then I add in the swift files, click yes to create bridging headers, but c++ doesn't see swift anymore. I'd greatly appreciate any suggestions.
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294
Aug ’25
CryptoTokenKit Network Cryptographic Tokens
Hello, It is mentioned in CryptoTokenKit documentation: You use the CryptoTokenKit framework to easily access cryptographic tokens. Tokens are physical devices built in to the system, located on attached hardware (like a smart card), or accessible through a network connection. However, it looks like there is lack of documentation with simple example, how to access network token. I have a certificates in HSM (hardware secure module), which is accessible on network, and I'd like to access certificates on HSM on my Mac. Does anybody know, where to start with implementation? Thank you.
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1.3k
Mar ’25
Cast Any to Sendable
I'm continuing with the migration towards Swift 6. Within one of our libraries, I want to check whether a parameter object: Any? confirms to Sendable. I tried the most obvious one: if let sendable = object as? Sendable { } But that results into the compiler error "Marker protocol 'Sendable' cannot be used in a conditional cast". Is there an other way to do this?
5
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1.4k
Mar ’25
Opening file from main bundle in Xcode 16
I've just upgraded to Xcode 16 and my app now fails when attempting to read a text file from the main bundle. It finds the path but can't open the file so this snippet prints: "File read error for path: /private/var/containers/Bundle/Application/AABAD428-96BC-4B34-80B4-97FA80B77E58/Test.app/csvfile.csv" This worked fine up to 15.4. Has something changed? Thanks. class ViewController: UIViewController { override func viewDidLoad() { super.viewDidLoad() let bundle = Bundle.main let path = bundle.path(forResource: "csvfile", ofType: "csv")! do { let content = try String(contentsOfFile: path, encoding: String.Encoding.ascii) } catch { print("File read error for path: \(String(describing: path))") } } }
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1.3k
Oct ’24
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?
2
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99
Jun ’25