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MultiThreaded rendering with actor
Hi, I'm trying to modify the ScreenCaptureKit Sample code by implementing an actor for Metal rendering, but I'm experiencing issues with frame rendering sequence. My app workflow is: ScreenCapture -> createFrame -> setRenderData Metal draw callback -> renderAsync (getData from renderData) I've added timestamps to verify frame ordering, I also using binarySearch to insert the frame with timestamp, and while the timestamps appear to be in sequence, the actual rendering output seems out of order. // ScreenCaptureKit sample func createFrame(for sampleBuffer: CMSampleBuffer) async { if let surface: IOSurface = getIOSurface(for: sampleBuffer) { await renderer.setRenderData(surface, timeStamp: sampleBuffer.presentationTimeStamp.seconds) } } class Renderer { ... func setRenderData(surface: IOSurface, timeStamp: Double) async { _ = await renderSemaphore.getSetBuffers( isGet: false, surface: surface, timeStamp: timeStamp ) } func draw(in view: MTKView) { Task { await renderAsync(view) } } func renderAsync(_ view: MTKView) async { guard await renderSemaphore.beginRender() else { return } guard let frame = await renderSemaphore.getSetBuffers( isGet: true, surface: nil, timeStamp: nil ) else { await renderSemaphore.endRender() return } guard let texture = await renderSemaphore.getRenderData( device: self.device, surface: frame.surface) else { await renderSemaphore.endRender() return } guard let commandBuffer = _commandQueue.makeCommandBuffer(), let renderPassDescriptor = await view.currentRenderPassDescriptor, let renderEncoder = commandBuffer.makeRenderCommandEncoder(descriptor: renderPassDescriptor) else { await renderSemaphore.endRender() return } // Shaders .. renderEncoder.endEncoding() commandBuffer.addCompletedHandler() { @Sendable (_ commandBuffer)-> Swift.Void in updateFPS() } // commit frame in actor let success = await renderSemaphore.commitFrame( timeStamp: frame.timeStamp, commandBuffer: commandBuffer, drawable: view.currentDrawable! ) if !success { print("Frame dropped due to out-of-order timestamp") } await renderSemaphore.endRender() } } actor RenderSemaphore { private var frameBuffers: [FrameData] = [] private var lastReadTimeStamp: Double = 0.0 private var lastCommittedTimeStamp: Double = 0 private var activeTaskCount = 0 private var activeRenderCount = 0 private let maxTasks = 3 private var textureCache: CVMetalTextureCache? init() { } func initTextureCache(device: MTLDevice) { CVMetalTextureCacheCreate(kCFAllocatorDefault, nil, device, nil, &self.textureCache) } func beginRender() -> Bool { guard activeRenderCount < maxTasks else { return false } activeRenderCount += 1 return true } func endRender() { if activeRenderCount > 0 { activeRenderCount -= 1 } } func setTextureLoaded(_ loaded: Bool) { isTextureLoaded = loaded } func getSetBuffers(isGet: Bool, surface: IOSurface?, timeStamp: Double?) -> FrameData? { if isGet { if !frameBuffers.isEmpty { let frame = frameBuffers.removeFirst() if frame.timeStamp > lastReadTimeStamp { lastReadTimeStamp = frame.timeStamp print(frame.timeStamp) return frame } } return nil } else { // Set let frameData = FrameData( surface: surface!, timeStamp: timeStamp! ) // insert to the right position let insertIndex = binarySearch(for: timeStamp!) frameBuffers.insert(frameData, at: insertIndex) return frameData } } private func binarySearch(for timeStamp: Double) -> Int { var left = 0 var right = frameBuffers.count while left < right { let mid = (left + right) / 2 if frameBuffers[mid].timeStamp > timeStamp { right = mid } else { left = mid + 1 } } return left } // for setRenderDataNormalized func tryEnterTask() -> Bool { guard activeTaskCount < maxTasks else { return false } activeTaskCount += 1 return true } func exitTask() { activeTaskCount -= 1 } func commitFrame(timeStamp: Double, commandBuffer: MTLCommandBuffer, drawable: MTLDrawable) async -> Bool { guard timeStamp > lastCommittedTimeStamp else { print("Drop frame at commit: \(timeStamp) <= \(lastCommittedTimeStamp)") return false } commandBuffer.present(drawable) commandBuffer.commit() lastCommittedTimeStamp = timeStamp return true } func getRenderData( device: MTLDevice, surface: IOSurface, depthData: [Float] ) -> (MTLTexture, MTLBuffer)? { let _textureName = "RenderData" var px: Unmanaged<CVPixelBuffer>? let status = CVPixelBufferCreateWithIOSurface(kCFAllocatorDefault, surface, nil, &px) guard status == kCVReturnSuccess, let screenImage = px?.takeRetainedValue() else { return nil } CVMetalTextureCacheFlush(textureCache!, 0) var texture: CVMetalTexture? = nil let width = CVPixelBufferGetWidthOfPlane(screenImage, 0) let height = CVPixelBufferGetHeightOfPlane(screenImage, 0) let result2 = CVMetalTextureCacheCreateTextureFromImage( kCFAllocatorDefault, self.textureCache!, screenImage, nil, MTLPixelFormat.bgra8Unorm, width, height, 0, &texture) guard result2 == kCVReturnSuccess, let cvTexture = texture, let mtlTexture = CVMetalTextureGetTexture(cvTexture) else { return nil } mtlTexture.label = _textureName let depthBuffer = device.makeBuffer(bytes: depthData, length: depthData.count * MemoryLayout<Float>.stride)! return (mtlTexture, depthBuffer) } } Above's my code - could someone point out what might be wrong?
7
0
738
Nov ’24
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
0
314
Mar ’25
Bridging Headers is unsupported or Module compiled with Swift 5.5.1 cannot be imported by the Swift 5.6 complier
Hello guys! I faced a problem with building... My device suddenly updated to iOS 15.4.1, my Xcode was 13.2 and I had to update it to the latest version (13.3.1) to build the app. After the update, I had a few problems which were successfully solved but one of them stopped me for a few hours. The problem is with Bridging Headers or Swift Compiler, I really don't know what I did badly, and what causes problems. On several forums I often read that is important to set: Build Settings > Build Options > Build Libraries for Distribution But in any case it doesn't work, on yes: error: using bridging headers with module interfaces is unsupported on no: (line with import framework SWXMLHash) /Users/blablabla/SSLModel.swift:9:8: error: module compiled with Swift 5.5.1 cannot be imported by the Swift 5.6 compiler: /Users/blablabla2/Build/Products/Debug-iphoneos/SWXMLHash.framework/Modules/SWXMLHash.swiftmodule/arm64-apple-ios.swiftmodule import SWXMLHash It will be important that I use Carthage. What should I do? Clone all 10 frameworks that I use and re-build them with a new Xcode which includes compiler 5.6? That may be a bad solution... Any answers on similar topics don't help..
3
0
2.9k
Jul ’25
Use FormatStyle to print formatted values from a Vector structure
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
2
0
294
Mar ’25
How to run `xctest` bundle - or how to add `entitlement` to test?
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.
2
0
1.4k
Mar ’25
@Observable class not compatible with Codable?
So any time I create a class that's both @Observable and Codable, e.g. @Observable class GameLocationManager : Codable { I get a warning in the macro expansion code: @ObservationIgnored private let _$observationRegistrar = Observation.ObservationRegistrar() Immutable property will not be decoded because it is declared with an initial value which cannot be overwritten. I've been ignoring them for now, but there are at least a half a dozen of them now in my (relatively small) codebase, and I'd like to find a solution (ideally one that doesn't require me to write init(decoder:) for every @Observable class in my project...), especially since I'm not sure what the actual consequences of ignoring this might be.
2
0
920
Nov ’24
json array shows in debugger but can't parse
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 :-)
2
0
335
Mar ’25
Compiler exception when using Binding and Swift 6
In my code I use a binding that use 2 methods to get and get a value. There is no problem with swift 5 but when I swift to swift 6 the compiler fails : Here a sample example of code to reproduce the problem : `import SwiftUI struct ContentView: View { @State private var isOn = false var body: some View { VStack { Image(systemName: "globe") .imageScale(.large) .foregroundStyle(.tint) Text("Hello, world!") Toggle("change it", isOn: Binding(get: getValue, set: setValue(_:))) } .padding() } private func getValue() -&gt; Bool { isOn } private func setValue(_ value: Bool) { isOn = value } }` Xcode compiler log error : 1. Apple Swift version 6.1.2 (swiftlang-6.1.2.1.2 clang-1700.0.13.5) 2. Compiling with the current language version 3. While evaluating request IRGenRequest(IR Generation for file "/Users/xavierrouet/Developer/TestCompilBindingSwift6/TestCompilBindingSwift6/ContentView.swift") 4. While emitting IR SIL function "@$sSbScA_pSgIeAghyg_SbIeAghn_TR". for &lt;&lt;debugloc at "&lt;compiler-generated&gt;":0:0&gt;&gt;Stack dump without symbol names (ensure you have llvm-symbolizer in your PATH or set the environment var LLVM_SYMBOLIZER_PATH` to point to it): 0 swift-frontend 0x000000010910ae24 llvm::sys::PrintStackTrace(llvm::raw_ostream&amp;, int) + 56 1 swift-frontend 0x0000000109108c5c llvm::sys::RunSignalHandlers() + 112 2 swift-frontend 0x000000010910b460 SignalHandler(int) + 360 3 libsystem_platform.dylib 0x0000000188e60624 _sigtramp + 56 4 libsystem_pthread.dylib 0x0000000188e2688c pthread_kill + 296 5 libsystem_c.dylib 0x0000000188d2fc60 abort + 124 6 swift-frontend 0x00000001032ff9a8 swift::DiagnosticHelper::~DiagnosticHelper() + 0 7 swift-frontend 0x000000010907a878 llvm::report_fatal_error(llvm::Twine const&amp;, bool) + 280 8 swift-frontend 0x00000001090aef6c report_at_maximum_capacity(unsigned long) + 0 9 swift-frontend 0x00000001090aec7c llvm::SmallVectorBase::grow_pod(void*, unsigned long, unsigned long) + 384 10 swift-frontend 0x000000010339c418 (anonymous namespace)::SyncCallEmission::setArgs(swift::irgen::Explosion&amp;, bool, swift::irgen::WitnessMetadata*) + 892 11 swift-frontend 0x00000001035f8104 (anonymous namespace)::IRGenSILFunction::visitFullApplySite(swift::FullApplySite) + 4792 12 swift-frontend 0x00000001035c876c (anonymous namespace)::IRGenSILFunction::visitSILBasicBlock(swift::SILBasicBlock*) + 2636 13 swift-frontend 0x00000001035c6614 (anonymous namespace)::IRGenSILFunction::emitSILFunction() + 15860 14 swift-frontend 0x00000001035c2368 swift::irgen::IRGenModule::emitSILFunction(swift::SILFunction*) + 2788 15 swift-frontend 0x00000001033e7c1c swift::irgen::IRGenerator::emitLazyDefinitions() + 5288 16 swift-frontend 0x0000000103573d6c swift::IRGenRequest::evaluate(swift::Evaluator&amp;, swift::IRGenDescriptor) const + 4528 17 swift-frontend 0x00000001035c15c4 swift::SimpleRequest&lt;swift::IRGenRequest, swift::GeneratedModule (swift::IRGenDescriptor), (swift::RequestFlags)17&gt;::evaluateRequest(swift::IRGenRequest const&amp;, swift::Evaluator&amp;) + 180 18 swift-frontend 0x000000010357d1b0 swift::IRGenRequest::OutputType swift::Evaluator::getResultUncached&lt;swift::IRGenRequest, swift::IRGenRequest::OutputType swift::evaluateOrFatalswift::IRGenRequest(swift::Evaluator&amp;, swift::IRGenRequest)::'lambda'()&gt;(swift::IRGenRequest const&amp;, swift::IRGenRequest::OutputType swift::evaluateOrFatalswift::IRGenRequest(swift::Evaluator&amp;, swift::IRGenRequest)::'lambda'()) + 812 19 swift-frontend 0x0000000103576910 swift::performIRGeneration(swift::FileUnit*, swift::IRGenOptions const&amp;, swift::TBDGenOptions const&amp;, std::__1::unique_ptr&lt;swift::SILModule, std::__1::default_deleteswift::SILModule&gt;, llvm::StringRef, swift::PrimarySpecificPaths const&amp;, llvm::StringRef, llvm::GlobalVariable**) + 176 20 swift-frontend 0x0000000102f61af0 generateIR(swift::IRGenOptions const&amp;, swift::TBDGenOptions const&amp;, std::__1::unique_ptr&lt;swift::SILModule, std::__1::default_deleteswift::SILModule&gt;, swift::PrimarySpecificPaths const&amp;, llvm::StringRef, llvm::PointerUnion&lt;swift::ModuleDecl*, swift::SourceFile*&gt;, llvm::GlobalVariable*&amp;, llvm::ArrayRef&lt;std::__1::basic_string&lt;char, std::__1::char_traits, std::__1::allocator&gt;&gt;) + 156 21 swift-frontend 0x0000000102f5d07c performCompileStepsPostSILGen(swift::CompilerInstance&amp;, std::__1::unique_ptr&lt;swift::SILModule, std::__1::default_deleteswift::SILModule&gt;, llvm::PointerUnion&lt;swift::ModuleDecl*, swift::SourceFile*&gt;, swift::PrimarySpecificPaths const&amp;, int&amp;, swift::FrontendObserver*) + 2108 22 swift-frontend 0x0000000102f5c0a8 swift::performCompileStepsPostSema(swift::CompilerInstance&amp;, int&amp;, swift::FrontendObserver*) + 1036 23 swift-frontend 0x0000000102f5f654 performCompile(swift::CompilerInstance&amp;, int&amp;, swift::FrontendObserver*) + 1764 24 swift-frontend 0x0000000102f5dfd8 swift::performFrontend(llvm::ArrayRef&lt;char const*&gt;, char const*, void*, swift::FrontendObserver*) + 3716 25 swift-frontend 0x0000000102ee20bc swift::mainEntry(int, char const**) + 5428 26 dyld 0x0000000188a86b98 start + 6076 Using Xcode 16.4 / Mac OS 16.4
3
0
226
Aug ’25
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
0
263
Mar ’25
Using Dynamic Member Lookup in a Superclass
As a fun project, I'm wanting to model an electronic circuit. Components inherit from a superclass (ElectronicComponent). Each subclass (e.g. Resistor) has certain methods to return properties (e.g. resistance), but may vary by the number of outlets (leads) they have, and what they are named. Each outlet connects to a Junction. In my code to assemble a circuit, while I'm able to manually hook up the outlets to the junctions, I'd like to be able to use code similar to the following… class Lead: Hashable // implementation omitted { let id = UUID() unowned let component: ElectronicComponent weak var connection: Junction? init(component: ElectronicComponent, to connection: Junction? = nil) { self.component = component self.connection = connection } } @dynamicMemberLookup class ElectronicComponent { let id = UUID() var connections: Set<Lead> = [] let label: String? init(label: String) { self.label = label } subscript<T>(dynamicMember keyPath: KeyPath<ElectronicComponent, T>) -> T { self[keyPath: keyPath] } func connect(lead: KeyPath<ElectronicComponent, Lead>, to junction: Junction) { let lead = self[keyPath: lead] lead.connection = junction connections.insert(lead) } } class Resistor: ElectronicComponent { var input, output: Lead? let resistance: Measurement<UnitElectricResistance> init(_ label: String, resistance: Measurement<UnitElectricResistance>) { self.resistance = resistance super.init(label: label) } } let resistorA = Resistor("R1", resistance: .init(value: 100, unit: .ohms)) let junctionA = Junction(name: "A") resistorA.connect(lead: \.outlet2, to: junctionA) While I'm able to do this by implementing @dynamicMemberLookup in each subclass, I'd like to be able to do this in the superclass to save repeating the code. subscript<T>(dynamicMember keyPath: KeyPath<ElectronicComponent, T>) -> T { self[keyPath: keyPath] } Unfortunately, the compiler is not allowing me to do this as the superclass doesn't know about the subclass properties, and at the call site, the subclass isn't seen as ElectronicComponent. I've been doing trial and error with protocol conformance and other things, but hitting walls each time. One possibility is replacing the set of outlets with a dictionary, and using Strings instead of key paths, but would prefer not to. Another thing I haven't tried is creating and adopting a protocol with the method implemented in there. Another considered approach is using macros in the subclasses, but I'd like to see if there is a possibility of achieving the goal using my current approach, for learning as much as anything.
6
0
393
Aug ’25
Tuple Comparision
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
2
0
460
Jul ’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.
2
0
900
Dec ’24
In app purchase goes to Entered Billing Retry after free trail
I have a VPN application published in the app store. Used Ikev2 for this personal VPN. There are two in-app purchases. One is 'Monthly' and another is 'Yearly' with 3 days free trial. We have seen something strange for the yearly subscriptions which has free trail, the cancellation reason through the billing issue is too high like 70-80% due to billing retry state. Some other apps which have billing issues under 10% always. We have done some research and found that if the user doesn't cancel and Apple is unable to charge then it goes to a billing retry state. If users don't like the app, they could cancel their subscription/free trail easily but they are not doing this and why Apple unable to charge the bill after the trial ends. Am i missing something in the developer end?
3
0
1.1k
Dec ’24
Swift 6 crash calling requestAutomaticPassPresentationSuppression
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.
2
0
473
Feb ’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!
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661
Jan ’25
Class not being called?
Hello, I was expecting the code below to print the test message "line 25" because the class "API" is being called on line 57. But "line 25" is not being displayed in the debug window, please could you tell me why? This is the debugging window: line 93 0 line 93 0 line 93 0 import UIKit // not sure these 2 below are needed import SwiftUI import Combine struct NewsFeed: Codable { var id: String var name: String var country: String var type: String var situation: String var timestamp: String } let urlString = "https://www.notafunnyname.com/jsonmockup.php" let url = URL(string: urlString) let session = URLSession.shared class API: ObservableObject { let dataTask = session.dataTask(with: url!) { (data, response, error) in print("line 25") 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 38") // print(newsFeed) // print("line 125") // print(newsFeed.count) print(error) } catch{ print("Line 46, Error in JSON parsing") print(error) } } }.resume // Make the API Call - not sure why but error clears if moved to line above // dataTask.resume() } let myAPIarray = API() 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) // #warning Incomplete implementation, return the number of rows print("line 93") 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 } } } }
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83
Mar ’25
Basic c++xcodeproj call to swift code
I have c++ macOs app(Xcode +14) and I try to add call to swift code. I can't find any simple c++ xcodeproj call to swift code. I create new simple project and fail to build it with error when I try to include #include <SwiftMixTester/SwiftMixTester-Swift.h>: main.m:9:10: error: 'SwiftMixTester/SwiftMixTester-Swift.h' file not found (in target 'CppCallSwift' from project 'CppCallSwift') note: Did not find header 'SwiftMixTester-Swift.h' in framework 'SwiftMixTester' (loaded from '/Users/yanivsmacm4/Library/Developer/Xcode/DerivedData/CppCallSwift-exdxjvwdcczqntbkksebulvfdolq/Build/Products/Debug') . Please help.
5
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384
1w