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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
DebugDescription macro causing “String Interpolation” warnings
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.
2
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467
Feb ’25
NSPredicate return wrong result
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?
2
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543
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)
2
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1.8k
Aug ’25
How to create an array using a loop
Hello, Please can you tell me how to create an array of dictionaries? This code below should create 4 dictionaries in an array, but I'm getting these errors: For line "var output = [id: "testID", name: "testName"]": cannot find 'name' in scope Type '(any AnyObject).Type' cannot conform to 'Hashable' For line "return output": Type '(any AnyObject).Type' cannot conform to 'Hashable' var quotes: [(id: String, name: String)] { var output = [[(id: String, name: String)]] () for i in 1...4 { var output = [id: "testID", name: "testName"] } return output }
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367
Mar ’25
Model instance invalidated, backing data could no longer be found in the store
I have been recently getting the following error seemingly randomly, when an event handler of a SwiftUI view accesses a relationship of a SwiftData model the view holds a reference to. I haven't yet found a reliable way of reproducing it: SwiftData/BackingData.swift:866: Fatal error: This model instance was invalidated because its backing data could no longer be found the store. PersistentIdentifier(id: SwiftData.PersistentIdentifier.ID(url: COREDATA_ID_URL), implementation: SwiftData.PersistentIdentifierImplementation) What could cause this error? Could you suggest me a workaround?
2
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924
Dec ’24
Beginner’s question on learning philosophy.
Hello Everyone! I started programming 6 months ago and started Swift / IOS last month. My learning so far has mainly been with Python. I learned a lot of the package ‘SQLAlchemy’, which has very ‘example based’ documentation. If I wanted to learn how to make a many to many relationship, there was a demonstration with code. But going into Swift and Apple packages, I notice most of the documentation is definitions of structures, modifiers, functions, etc. I wanted to make the equivalent of python ‘date times’ in my swift app. I found the section in the documentation “Foundation->Dates & Times”, but I couldn’t figure how to use that in my code. I assume my goal should not be to memorize every Swift and apple functionality by memory to be an app developer. So I would appreciate advice on how to approach this aspect of learning programming.
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435
Oct ’25
Label cannot export localized string key
Hello all. This is my code snippet. RecordListView() .tabItem { Label("Record List", systemImage: "list.clipboard") } .tag(Tab.RecordList) When I export localizations, there is no Record List in the .xcloc file. Then I use LocalizedStringKey for Label and export localizations file, the code is as follows: let RecordsString:LocalizedStringKey = "Tab.Records" RecordListView() .tabItem { Label(RecordsString, systemImage: "list.clipboard") } .tag(Tab.RecordList) There is still no Tab.Records.
2
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616
Nov ’24
iOS Share Extension Warning: Passing argument of non-sendable type outside of main actor-isolated context may introduce data races
Consider this simple miniature of my iOS Share Extension: import SwiftUI import Photos class ShareViewController: UIViewController { override func viewDidLoad() { super.viewDidLoad() if let itemProviders = (extensionContext?.inputItems.first as? NSExtensionItem)?.attachments { let hostingView = UIHostingController(rootView: ShareView(extensionContext: extensionContext, itemProviders: itemProviders)) hostingView.view.frame = view.frame view.addSubview(hostingView.view) } } } struct ShareView: View { var extensionContext: NSExtensionContext? var itemProviders: [NSItemProvider] var body: some View { VStack{} .task{ await extractItems() } } func extractItems() async { guard let itemProvider = itemProviders.first else { return } guard itemProvider.hasItemConformingToTypeIdentifier(UTType.url.identifier) else { return } do { guard let url = try await itemProvider.loadItem(forTypeIdentifier: UTType.url.identifier) as? URL else { return } try await downloadAndSaveMedia(reelURL: url.absoluteString) extensionContext?.completeRequest(returningItems: []) } catch {} } } On the line 34 guard let url = try await itemProvider.loadItem ... I get these warnings: Passing argument of non-sendable type '[AnyHashable : Any]?' outside of main actor-isolated context may introduce data races; this is an error in the Swift 6 language mode 1.1. Generic enum 'Optional' does not conform to the 'Sendable' protocol (Swift.Optional) Passing argument of non-sendable type 'NSItemProvider' outside of main actor-isolated context may introduce data races; this is an error in the Swift 6 language mode 2.2. Class 'NSItemProvider' does not conform to the 'Sendable' protocol (Foundation.NSItemProvider) How to fix them in Xcode 16? Please provide a solution which works, and not the one which might (meaning you run the same code in Xcode, add your solution and see no warnings). I tried Decorating everything with @MainActors Using @MainActor in the .task @preconcurrency import Decorating everything with @preconcurrency Playing around with nonisolated
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523
Mar ’25
Asynchronous json retrieval
Hello, I am getting an error message "Cannot convert value of type 'URLSessionDataTask' to expected argument type 'Data'" for the last line of this code. Please can you tell me what the problem is? Thank you struct Item : Codable { var id: String var name: String var country: String var type: String var overallrecsit: String var dlastupd: String var doverallrecsit: String } let url = URL(string:"https://www.TEST_URL.com/api_ios.php") let json = try? JSONDecoder().decode(Item.self, from: URLSession.shared.dataTask(with: url!))
1
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314
Mar ’25
Playing Timed Sound Effects in Background
Hi, I'm relatively new to iOS development and kindly ask for some feedback on a strategy to achieve this desired behavior in my app. My Question: What would be the best strategy for sound effect playback when an app is in the background with precise timing? Is this even possible? Context: I created a basic countdown timer app (targeting iOS 17 with Swift/SwiftUI.). Countdown sessions can last up to 30-60 mins. When the timer is started it progresses through a series of sub-intervals and plays a short sound for each one. I used AVAudioPlayer and everything works fine when the app is in the foreground. I'm considering switching to AVAudioEngine b/c precise timing is very important and the AIs tell me this would have better precision. I'm already setting "App plays audio or streams audio/video using AirPlay" in my Plist, and have configured: AVAudioSession.sharedInstance().setCategory(.playback, mode: .default, options: .mixWithOthers) Curiously, when testing on my iPhone 13 mini, sounds sometimes still play when the app is in the background, but not always. What I've considered: Background Tasks: Would they make any sense for this use-case? Seems like not if the allowed time is short & limited by the system. Pre-scheduling all Sounds: Not sure this would even work and seems like a lot of memory would be needed (could be hundreds of intervals). ActivityKit Alerts: works but with a ~50ms delay which is too long for my purposes. Pre-Render all SFX to 1 large audio file: Seems like a lot of work and processing time and probably not worth it. I hope there's a better solution. I'd really appreciate any feedback.
1
0
1.2k
Dec ’24
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.
1
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446
Dec ’24
Using `@ObservedObject` in a function
No real intruduction for this, so I'll get to the point: All this code is on GitHub: https://github.com/the-trumpeter/Timetaber-for-iWatch But first, sorry; /* I got roasted, last time I posted; for not defining my stuff. This'll be different, but's gonna be rough; 'cuz there's lots and lots to get through: */ //this is 'Timetaber Watch App/Define (No expressions)/Courses_vDef.swift' on the GitHub: struct Course { let name: String let icon: String let room: String let colour: String let listName: String let listIcon: String let joke: String init(name: String, icon: String, room: String? = nil, colour: String, listName: String? = nil, listIcon: String? = nil, joke: String? = nil) { self.name = name self.icon = icon self.room = room ?? "None" self.colour = colour self.listName = listName ?? name self.listIcon = listIcon ?? (icon+".circle.fill") self.joke = joke ?? "" } } //this is 'Timetaber Watch App/TimeManager_fDef.swift' on the GitHub: func getCurrentClass(date: Date) -> Array<Course> { //returns the course in session depending on the input date //it is VERY long but //all you really need to know is what it returns: //basically: return [rightNow, nextUp] } /* I thought that poetry would be okay, But poorly thought things through: For I'll probably find that people online will treat my rhymes like spew. */ So into the question: I have a bunch of views, all (intendedly) watching two variables inside of a class: //Github: 'Timetaber Watch App/TimetaberApp.swift' class GlobalData: ObservableObject { @Published var currentCourse: Course = getCurrentClass(date: .now)[0] // the current timetabled class in session. @Published var nextCourse: Course = getCurrentClass(date: .now)[1] // the next timetabled class in session } ...and a bunch of views using them in different ways as follows: (Sorry, don't have the characters to define functions called in these) import SwiftUI //Github: 'Timetaber Watch App/Views/HomeView.swift' struct HomeView: View { @StateObject var data = GlobalData() var body: some View { //HERE: let icon = data.currentCourse.icon let name = data.currentCourse.name let colour = data.currentCourse.colour let room = roomOrBlank(course: data.currentCourse) let next = data.nextCourse VStack { //CURRENT CLASS Image(systemName: icon) .foregroundColor(Color(colour))//add an SF symbol element .imageScale(.large) .font(.system(size: 25).weight(.semibold)) Text(name) .font(.system(size:23).weight(.bold)) .foregroundColor(Color(colour)) .padding(.bottom, 0.1) //ROOM Text(room+"\n") .multilineTextAlignment(.center) .foregroundStyle(.gray) .font(.system(size: 15)) if next.name != noSchool.name { Spacer() //NEXT CLASS Text(nextPrefix(course: next)) .font(.system(size: 15)) Text(getNextString(course: next)) .font(.system(size: 15)) .multilineTextAlignment(.center) } }.padding() } } // Github: 'Timetaber Watch App/Views/ListView.swift' struct listTemplate: View { @StateObject var data = GlobalData() var listedCourse: Course = failCourse(feedback: "lT.12") var courseTime: String = "" init(course: Course, courseTime: String) { self.courseTime = courseTime self.listedCourse = course } var body: some View { let localroom = if listedCourse.room == "None" { "" } else { listedCourse.room } let image = if listedCourse.listIcon == "custom1" { Image(.paintbrushPointedCircleFill) } else { Image(systemName: listedCourse.listIcon) } HStack{ image .foregroundColor(Color(listedCourse.colour)) .padding(.leading, 5) Text(listedCourse.name) .bold() Spacer() Text(courseTime) Text(localroom).bold().padding(.trailing, 5) } .padding(.bottom, 1) .background(data.currentCourse.name==listedCourse.name ? Color(listedCourse.colour).colorInvert(): nil) //HERE } } struct listedDay: View { let day: Dictionary<Int, Course> var body: some View { let dayKeys = Array(day.keys).sorted(by: <) List { ForEach((0...dayKeys.count-2), id: \.self) { let num = $0 listTemplate(course: day[dayKeys[num]] ?? failCourse(feedback: "lD.53"), courseTime: time24toNormal(time24: dayKeys[num])) } } } } struct ListView: View { var body: some View { if storage.shared.termRunningGB && weekdayFunc(inDate: .now) != 1 && weekdayFunc(inDate: .now) != 7 { ScrollView { listedDay( day: getTimetableDay( isWeekA: getIfWeekIsA_FromDateAndGhost( originDate: .now, ghostWeek: storage.shared.ghostWeekGB ), weekDay: weekdayFunc(inDate: .now) ) ) } } else if !storage.shared.termRunningGB { Text("There's no term running.\nThe day's classes will be displayed here.") .multilineTextAlignment(.center) .foregroundStyle(.gray) .font(.system(size: 13)) } else { Text("No school today.\nThe day's classes will be displayed here.") .multilineTextAlignment(.center) .foregroundStyle(.gray) .font(.system(size: 13)) } } } //There's one more view but I can't fit it for characters. //On GitHub: 'Timetaber Watch App/Views/SettingsView.swift' So... THE FUNCTION: This function is called when changes are made that will affect the correct output of getCurrentClass. It is intended to reload the views and the current/next variables to reflect those changes.\ //GHub: 'Timetaber Watch App/StorageManager.swift' func reload() -> Void { @ObservedObject var globalData: GlobalData //this line is erroring, I don't know how to fix it. Is this even the best/proper way to do this? let courseData = getCurrentClass(date: .now) globalData.currentCourse = courseData[0] globalData.nextCourse = courseData[1] //Variable '_globalData' used by function definition before being initialized //that is the error appearing on those above two redefinitions. print("Setup done\n") } Thanks! -Gill
1
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263
Mar ’25
json array shows in debugger but can't parse
Hello, I asked this question on 9th March but was asked to provide a project file and can't edit the original post. Please find the original question below and please find the new test project file at https://we.tl/t-fqAu8FrgUw. 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 the catch error "Error in JSON parsing" 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(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 :-)
1
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332
Mar ’25
Not understanding synchronous/asynchronous code
Hello, For the below code please can you tell me why the test code print("line 64") is being printed after the test code print("line 84") ? (i.e. how do I stop that happening?) I would like the program to wait until the results array has been parsed before continuing the code (otherwise it does not have content to present). I'm a bit confused why this is happening because I haven't written "async" anywhere. import UIKit struct NewsFeed: Codable { var id: String var name: String var country: String var type: String var situation: String var timestamp: String } class QuoteTableViewController: UITableViewController { var newsFeed: [[String: String]] = [] override func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) { // let selectedQuote = quotes[indexPath.row] // performSegue(withIdentifier: "moveToQuoteDetail", sender: selectedQuote) } override func viewDidLoad() { super.viewDidLoad() // tableView.dataSource = self } // Uncomment the following line to preserve selection between presentations // self.clearsSelectionOnViewWillAppear = false // Uncomment the following line to display an Edit button in the navigation bar for this view controller. // self.navigationItem.rightBarButtonItem = self.editButtonItem // MARK: - Table view data source override func numberOfSections(in tableView: UITableView) -> Int { // #warning Incomplete implementation, return the number of sections return 1 } override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int { // (viewDidLoad loads after tableView) // try getting array results here let urlString = "https://www.notafunnyname.com/jsonmockup.php" let url = URL(string: urlString) let session = URLSession.shared let dataTask = session.dataTask(with: url!) { (data, response, error) in var dataString = String(data: data!, encoding: String.Encoding.utf8) if error == nil && data != nil { // Parse JSON let decoder = JSONDecoder() do { var newsFeed = try decoder.decode([NewsFeed].self, from: data!) print("line 64") // print(newsFeed) // print("line 125") // print(newsFeed.count) print(error) } catch{ print("Line 72, Error in JSON parsing") print(error) } } } // Make the API Call dataTask.resume() // #warning Incomplete implementation, return the number of rows print("line 84") print(newsFeed.count) return 10 } override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell { // let cell = tableView.dequeueReusableCell(withIdentifier: "reuseIdentifier", for: indexPath) let cell = UITableViewCell () cell.textLabel?.text = "test" return cell } /* // Override to support conditional editing of the table view. override func tableView(_ tableView: UITableView, canEditRowAt indexPath: IndexPath) -> Bool { // Return false if you do not want the specified item to be editable. return true } */ /* // Override to support editing the table view. override func tableView(_ tableView: UITableView, commit editingStyle: UITableViewCell.EditingStyle, forRowAt indexPath: IndexPath) { if editingStyle == .delete { // Delete the row from the data source tableView.deleteRows(at: [indexPath], with: .fade) } else if editingStyle == .insert { // Create a new instance of the appropriate class, insert it into the array, and add a new row to the table view } } */ /* // Override to support rearranging the table view. override func tableView(_ tableView: UITableView, moveRowAt fromIndexPath: IndexPath, to: IndexPath) { } */ /* // Override to support conditional rearranging of the table view. override func tableView(_ tableView: UITableView, canMoveRowAt indexPath: IndexPath) -> Bool { // Return false if you do not want the item to be re-orderable. return true } */ // MARK: - Navigation // In a storyboard-based application, you will often want to do a little preparation before navigation override func prepare(for segue: UIStoryboardSegue, sender: Any?) { // Get the new view controller using segue.destination. // Pass the selected object to the new view controller. // getPrice() print("test_segue") if let quoteViewController = segue.destination as? QuoteDetailViewController{ if let selectedQuote = sender as? String { quoteViewController.title = selectedQuote } } } } Many thanks
1
0
102
Mar ’25
Symbol not found: (_objc_claimAutoreleasedReturnValue)
When I run app, it works on iOS16+ device. But when I run on iOS15 device just working on debug mode, if I run release or profile modeI got runtime error: Log: (lldb) dyld[4928]: Symbol not found: (_objc_claimAutoreleasedReturnValue) Referenced from: '/private/var/containers/Bundle/Application/C724D7C6-82FA-4AF3-AE83-EC035B4429A5/Runner.app/Frameworks/geolocator_apple.framework/geolocator_apple' Expected in: '/usr/lib/libobjc.A.dylib' thread #1, stop reason = signal SIGABRT frame #0: 0x0000000106cbb2cc dyld`__abort_with_payload + 8 dyld`__abort_with_payload: -&amp;gt; 0x106cbb2cc &amp;lt;+8&amp;gt;: b.lo 0x106cbb2e8 ; &amp;lt;+36&amp;gt; 0x106cbb2d0 &amp;lt;+12&amp;gt;: stp x29, x30, [sp, #-0x10]! 0x106cbb2d4 &amp;lt;+16&amp;gt;: mov x29, sp 0x106cbb2d8 &amp;lt;+20&amp;gt;: bl 0x106c8164c ; cerror_nocancel Target 0: (Runner) stopped. Flutter doctor : Doctor summary (to see all details, run flutter doctor -v): [✓] Flutter (Channel stable, 3.29.2, on macOS 15.2 24C101 darwin-arm64, locale en-VN) [✓] Android toolchain - develop for Android devices (Android SDK version 34.0.0) [✓] Xcode - develop for iOS and macOS (Xcode 16.2) [✓] Chrome - develop for the web [✓] Android Studio (version 2024.2) [✓] VS Code (version 1.97.2)
1
0
185
Mar ’25
Swift/objC combined with Swift/C++ interop
Consider this Swift struct: public struct Example { public func foo(callback: ()->Void) { .... } public func blah(i: Int) { .... } .... } Using Swift/C++ interop, I can create Example objects and call methods like blah. But I can't call foo because Swift/C++ interop doesn't currently support passing closures (right?). On the other hand, Swift/objC does support passing objC blocks to Swift functions. But I can't use that here because Example is a Swift struct, not a class. So I could change it to a class, and update everything to work with reference rather than value semantics; but then I also have to change the objC++ code to create the object and call its methods using objC syntax. I'd like to avoid that. Is there some hack that I can use to make this possible? I'm hoping that I can wrap a C++ std::function in some sort of opaque wrapper and pass that to swift, or something. Thanks for any suggestions!
1
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662
Jan ’25
Why does Array.contains cause a compile-time error when comparing an optional value with a non-optional value in Swift?
I’m working with Swift and ran into an issue when using the contains(_:) method on an array. The following code works fine: let result = ["hello", "world"].contains(Optional("hello")) // ✅ Works fine But when I try to use the same contains method with the array declared in a separate variable, I get a compile-time error: let stringArray = ["hello", "world"] let result = stringArray.contains(Optional("hello")) // ❌ Compile-time error Both examples seem conceptually similar, but the second one causes a compile-time error, while the first one works fine. I understand that when comparing an optional value (Optional("hello")) with a non-optional value ("hello"), Swift automatically promotes the non-optional value to an optional (i.e., "hello" becomes Optional("hello")). 🔗 reference What I don’t understand is why the first code works but the second one doesn’t, even though both cases involve comparing an optional value with a non-optional value. I know that there are different ways to resolve this, like using nil coalescing or optional binding, but what I’m really looking for is a detailed explanation of why this issue occurs at the compile-time level. Can anyone explain the underlying reason for this behavior?
1
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81
Mar ’25
Working correctly with actor annotated class
Hi, I have a complex structure of classes, and I'm trying to migrate to swift6 For this classes I've a facade that creates the classes for me without disclosing their internals, only conforming to a known protocol I think I've hit a hard wall in my knowledge of how the actors can exchange data between themselves. I've created a small piece of code that can trigger the error I've hit import SwiftUI import Observation @globalActor actor MyActor { static let shared: some Actor = MyActor() init() { } } @MyActor protocol ProtocolMyActor { var value: String { get } func set(value: String) } @MyActor func make(value: String) -> ProtocolMyActor { return ImplementationMyActor(value: value) } class ImplementationMyActor: ProtocolMyActor { private(set) var value: String init(value: String) { self.value = value } func set(value: String) { self.value = value } } @MainActor @Observable class ViewObserver { let implementation: ProtocolMyActor var value: String init() async { let implementation = await make(value: "Ciao") self.implementation = implementation self.value = await implementation.value } func set(value: String) { Task { await implementation.set(value: value) self.value = value } } } struct MyObservedView: View { @State var model: ViewObserver? var body: some View { if let model { Button("Loaded \(model.value)") { model.set(value: ["A", "B", "C"].randomElement()!) } } else { Text("Loading") .task { self.model = await ViewObserver() } } } } The error Non-sendable type 'any ProtocolMyActor' passed in implicitly asynchronous call to global actor 'MyActor'-isolated property 'value' cannot cross actor boundary Occurs in the init on the line "self.value = await implementation.value" I don't know which concurrency error happens... Yes the init is in the MainActor , but the ProtocolMyActor data can only be accessed in a MyActor queue, so no data races can happen... and each access in my ImplementationMyActor uses await, so I'm not reading or writing the object from a different actor, I just pass sendable values as parameter to a function of the object.. can anybody help me understand better this piece of concurrency problem? Thanks
1
0
596
Nov ’24