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How to implement thread-safe property wrapper notifications across different contexts in Swift?
I’m trying to create a property wrapper that that can manage shared state across any context, which can get notified if changes happen from somewhere else. I'm using mutex, and getting and setting values works great. However, I can't find a way to create an observer pattern that the property wrappers can use. The problem is that I can’t trigger a notification from a different thread/context, and have that notification get called on the correct thread of the parent object that the property wrapper is used within. I would like the property wrapper to work from anywhere: a SwiftUI view, an actor, or from a class that is created in the background. The notification preferably would get called synchronously if triggered from the same thread or actor, or otherwise asynchronously. I don’t have to worry about race conditions from the notification because the state only needs to reach eventuall consistency. Here's the simplified pseudo code of what I'm trying to accomplish: // A single source of truth storage container. final class MemoryShared<Value>: Sendable { let state = Mutex<Value>(0) func withLock(_ action: (inout Value) -> Void) { state.withLock(action) notifyObservers() } func get() -> Value func notifyObservers() func addObserver() } // Some shared state used across the app static let globalCount = MemoryShared<Int>(0) // A property wrapper to access the shared state and receive changes @propertyWrapper struct SharedState<Value> { public var wrappedValue: T { get { state.get() } nonmutating set { // Can't set directly } } var publisher: Publisher {} init(state: MemoryShared) { // ... } } // I'd like to use it in multiple places: @Observable class MyObservable { @SharedState(globalCount) var count: Int } actor MyBackgroundActor { @SharedState(globalCount) var count: Int } @MainActor struct MyView: View { @SharedState(globalCount) var count: Int } What I’ve Tried All of the examples below are using the property wrapper within a @MainActor class. However the same issue happens no matter what context I use the wrapper in: The notification callback is never called on the context the property wrapper was created with. I’ve tried using @isolated(any) to capture the context of the wrapper and save it to be called within the state in with unchecked sendable, which doesn’t work: final class MemoryShared<Value: Sendable>: Sendable { // Stores the callback for later. public func subscribe(callback: @escaping @isolated(any) (Value) -> Void) -> Subscription } @propertyWrapper struct SharedState<Value> { init(state: MemoryShared<Value>) { MainActor.assertIsolated() // Works! state.subscribe { MainActor.assertIsolated() // Fails self.publisher.send() } } } I’ve tried capturing the isolation within a task with AsyncStream. This actually compiles with no sendable issues, but still fails: @propertyWrapper struct SharedState<Value> { init(isolation: isolated (any Actor)? = #isolation, state: MemoryShared<Value>) { let (taskStream, continuation) = AsyncStream<Value>.makeStream() // The shared state sends new values to the continuation. subscription = state.subscribe(continuation: continuation) MainActor.assertIsolated() // Works! let task = Task { _ = isolation for await value in taskStream { _ = isolation MainActor.assertIsolated() // Fails } } } } I’ve tried using multiple combine subjects and publishers: final class MemoryShared<Value: Sendable>: Sendable { let subject: PassthroughSubject<T, Never> // ... var publisher: Publisher {} // ... } @propertyWrapper final class SharedState<Value> { var localSubject: Subject init(state: MemoryShared<Value>) { MainActor.assertIsolated() // Works! handle = localSubject.sink { MainActor.assertIsolated() // Fails } stateHandle = state.publisher.subscribe(localSubject) } } I’ve also tried: Using NotificationCenter Making the property wrapper a class Using NSKeyValueObserving Using a box class that is stored within the wrapper. Using @_inheritActorContext. All of these don’t work, because the event is never called from the thread the property wrapper resides in. Is it possible at all to create an observation system that notifies the observer from the same context as where the observer was created? Any help would be greatly appreciated!
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460
Mar ’25
Weird crashes when accessing Swift Array
For some time now Xcode has been downloading crash reports from users of my app about crashes related to arrays. One of them looks like this: ... Code Type: ARM-64 Parent Process: launchd [1] User ID: 501 Date/Time: 2024-07-18 14:59:40.4375 +0800 OS Version: macOS 15.0 (24A5289h) ... Crashed Thread: 0 Exception Type: EXC_BREAKPOINT (SIGTRAP) Exception Codes: 0x0000000000000001, 0x00000001045048b8 Termination Reason: Namespace SIGNAL, Code 5 Trace/BPT trap: 5 Terminating Process: exc handler [1771] Thread 0 Crashed: 0 MyApp 0x00000001045048b8 specialized Collection.map<A>(_:) + 596 1 MyApp 0x00000001045011e4 MyViewController.validateToolbarButtons() + 648 (MyViewController.swift:742) ... The relevant code looks like this: class MyViewController { func validateToolbarButtons() { let indexes = tableView.clickedRow == -1 || tableView.selectedRowIndexes.contains(tableView.clickedRow) ? tableView.selectedRowIndexes : IndexSet(integer: tableView.clickedRow) let items = indexes.map({ myArray[$0] }) ... } } The second crash looks like this: ... Code Type: X86-64 (Native) Parent Process: launchd [1] User ID: 502 Date/Time: 2024-07-15 15:53:35.2229 -0400 OS Version: macOS 15.0 (24A5289h) ... Crashed Thread: 0 Exception Type: EXC_BAD_INSTRUCTION (SIGILL) Exception Codes: 0x0000000000000001, 0x0000000000000000 Termination Reason: Namespace SIGNAL, Code 4 Illegal instruction: 4 Terminating Process: exc handler [13244] Thread 0 Crashed: 0 libswiftCore.dylib 0x00007ff812904fc0 _assertionFailure(_:_:flags:) + 288 1 MyApp 0x0000000101a31e04 specialized _ArrayBuffer._getElementSlowPath(_:) + 516 2 MyApp 0x00000001019d04eb MyObject.myProperty.setter + 203 (MyObject.swift:706) 3 MyApp 0x000000010192f66e MyViewController.controlTextDidChange(_:) + 190 (MyViewController.swift:166) ... And the relevant code looks like this: class MyObject { var myProperty: [MyObject] { get { ... } set { let items = newValue.map({ $0.id }) ... } } } What could cause such crashes? Could they be caused by anything other than concurrent access from multiple threads (which I'm quite sure is not the case here, as I only access these arrays from the main thread)?
16
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2.2k
Mar ’25
Swift 6 Concurrency errors with ModelActor, or Core Data actors
In my app, I've been using ModelActors in SwiftData, and using actors with a custom executor in Core Data to create concurrency safe services. I have multiple actor services that relate to different data model components or features, each that have their own internally managed state (DocumentService, ImportService, etc). The problem I've ran into, is that I need to be able to use multiple of these services within another service, and those services need to share the same context. Swift 6 doesn't allow passing contexts across actors. The specific problem I have is that I need a master service that makes multiple unrelated changes without saving them to the main context until approved by the user. I've tried to find a solution in SwiftData and Core Data, but both have the same problem which is contexts are not sendable. Read the comments in the code to see the issue: /// This actor does multiple things without saving, until committed in SwiftData. @ModelActor actor DatabaseHelper { func commitChange() throws { try modelContext.save() } func makeChanges() async throws { // Do unrelated expensive tasks on the child context... // Next, use our item service let service = ItemService(modelContainer: SwiftDataStack.shared.container) let id = try await service.expensiveBackgroundTask(saveChanges: false) // Now that we've used the service, we need to access something the service created. // However, because the service created its own context and it was never saved, we can't access it. let itemFromService = context.fetch(id) // fails // We need to be able to access changes made from the service within this service, /// so instead I tried to create the service by passing the current service context, however that results in: // ERROR: Sending 'self.modelContext' risks causing data races let serviceFromContext = ItemService(context: modelContext) // Swift Data doesn't let you create child contexts, so the same context must be used in order to change data without saving. } } @ModelActor actor ItemService { init(context: ModelContext) { modelContainer = SwiftDataStack.shared.container modelExecutor = DefaultSerialModelExecutor(modelContext: context) } func expensiveBackgroundTask(saveChanges: Bool = true) async throws -> PersistentIdentifier? { // Do something expensive... return nil } } Core Data has the same problem: /// This actor does multiple things without saving, until committed in Core Data. actor CoreDataHelper { let parentContext: NSManagedObjectContext let context: NSManagedObjectContext /// In Core Data, I can create a child context from a background context. /// This lets you modify the context and save it without updating the main context. init(progress: Progress = Progress()) { parentContext = CoreDataStack.shared.newBackgroundContext() let childContext = NSManagedObjectContext(concurrencyType: .privateQueueConcurrencyType) childContext.parent = parentContext self.context = childContext } /// To commit changes, save the parent context pushing them to the main context. func commitChange() async throws { // ERROR: Sending 'self.parentContext' risks causing data races try await parentContext.perform { try self.parentContext.save() } } func makeChanges() async throws { // Do unrelated expensive tasks on the child context... // As with the Swift Data example, I am unable to create a service that uses the current actors context from here. // ERROR: Sending 'self.context' risks causing data races let service = ItemService(context: self.context) } } Am I going about this wrong, or is there a solution to fix these errors? Some services are very large and have their own internal state. So it would be very difficult to merge all of them into a single service. I also am using Core Data, and SwiftData extensively so I need a solution for both. I seem to have trapped myself into a corner trying to make everything concurrency save, so any help would be appreciated!
6
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777
Mar ’25
ARKit hand tracking
Hello, I am developing a visionOS application and am interested in obtaining detailed data of users’ hands through ARKit, including but not limited to Transform and rotation angle. I have reviewed Happy Beem, but it appears to only introduce the method of identifying the user’s specific gestures. Could you please advise on how to obtain the Transform and rotation angle of the user’s hand? Thank you.
1
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440
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
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1.4k
Mar ’25
Optimal Way of Getting Screen Resolution Using SwiftUI
Hi all, I am looking for a futureproof way of getting the Screen Resolution of my display device using SwiftUI in MacOS. I understand that it can't really be done to the fullest extent, meaning that the closest API we have is the GeometeryProxy and that would only result in the resolution of the parent view, which in the MacOS case would not give us the display's screen resolution. The only viable option I am left with is NSScreen.frame. However, my issue here is that it seems like Apple is moving towards SwiftUI aggressively, and in order to futureproof my application I need to not rely on AppKit methods as much. Hence, my question: Is there a way to get the Screen Resolution of a Display using SwiftUI that Apple itself recommends? If not, then can I rely safely on NSScreen's frame API?
3
1
382
Mar ’25
I'm trying to use a keychain-access-group and failing
This is on macOS, not iOS. Not sure if that should make a difference? I have a GUI app and a command line tool (that will run a daemon) that I need to share credentials between. The keys/certs will be stored using the GUI app. But, both tools need to utilize them. guard let accessControl = SecAccessControlCreateWithFlags( nil, kSecAttrAccessibleWhenPasscodeSetThisDeviceOnly, [.privateKeyUsage], nil ) else { throw KeychainCertError.keychainError(errSecAuthFailed, "Failed to create access control for private key") } // Define Key Pair Attributes let privateKeyAttributes: [String: Any] = [ kSecAttrIsPermanent as String: true, kSecAttrApplicationTag as String: privateLabel.data(using: .utf8)!, kSecAttrLabel as String: privateLabel, // kSecAttrAccessControl as String: accessControl, kSecAttrAccessGroup as String: keychainAccessGroup ] With the kSecAttrAccessControl commented out, I am able to generate a private key and generate a self signed certificate that is stored on the user login keychain. If I uncomment that line, I get an error to the affect of "Keychain error (-26275): Failed to generate key pair: A required entitlement isn't present" Also, to share the credentials, don't they need to be NOT on the user keychain for the daemon to access them? Any ideas what I am doing wrong? I think I'm a bit over my head here with the the security, crypto kit and openssl. 😁
6
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450
Mar ’25
JournalingSuggestions Crashes on iOS 18 Simulator with Xcode 16.2 – Linker Error
I’m running into an issue while implementing JournalingSuggestions with Xcode 16.2 and the iOS 18 simulator. My code builds and runs fine on a physical device, but it consistently crashes on the simulator and in Xcode previews. I’ve tried several workarounds, including weak linking and solutions from this post (746843), but I’m still hitting a wall. Here’s what’s happening: I get a warning: JournalingSuggestions is not available when building for iOS Simulator. This is followed by a build error: Linker command failed with exit code 1 (use -v to see invocation). What I’ve Tried: Weak linking the JournalingSuggestions framework. Applying fixes from this post (746843), such as cleaning the build folder and using weak link. Deleting Derived Data and rebuilding. Testing on a physical device (works fine). My Setup: Xcode Version: 16.2 Simulator: iOS 18 Build Success: Works on physical device, fails on simulator/preview Code: #if canImport(JournalingSuggestions) import JournalingSuggestions #endif ... var suggestionButton: some View { #if canImport(JournalingSuggestions) #if !targetEnvironment(simulator) if #available(iOS 17.2, *) { return AnyView(journalingSuggestionsPickerButton) } #endif return AnyView(disabledSuggestionButton) #else return AnyView(disabledSuggestionButton) #endif }
1
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269
Mar ’25
ActiveLabel
Hey Everyone, I can't see to ActiveLabel as it says there is no active module. Please help me. Thanks, Ben import UIKit import ActiveLabel protocol TweetCellDelegate: AnyObject { func handleProfileImageTapped(_ cell: TweetCell) func handleReplyTapped(_ cell: TweetCell) func handleLikeTapped(_ cell: TweetCell) } class TweetCell: UICollectionViewCell {
0
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226
Mar ’25
How to properly pass a Metal layer from SwiftUI MTKView to C++ for use with metal-cpp?
Hello! I'm currently porting a videogame console emulator to iOS and I'm trying to make the renderer (tested on MacOS) work on iOS as well. The emulator core is written in C++ and uses metal-cpp for rendering, whereas the iOS frontend is written in Swift with SwiftUI. I have an Objective-C++ bridging header for bridging the Swift and C++ sides. On the Swift side, I create an MTKView. Inside the MTKView delegate, I run the emulator for 1 video frame and pass it the view's backing layer for it to render the final output image with. The emulator runs and returns, but when it returns I get a crash in Swift land (callstack attached below), inside objc_release, which indicates I'm doing something wrong with memory management. My bridging interface (ios_driver.h): #pragma once #include <Foundation/Foundation.h> #include <QuartzCore/QuartzCore.h> void iosCreateEmulator(); void iosRunFrame(CAMetalLayer* layer); Bridge implementation (ios_driver.mm): #import <Foundation/Foundation.h> extern "C" { #include "ios_driver.h" } <...> #define IOS_EXPORT extern "C" __attribute__((visibility("default"))) std::unique_ptr<Emulator> emulator = nullptr; IOS_EXPORT void iosCreateEmulator() { ... } // Runs 1 video frame of the emulator and IOS_EXPORT void iosRunFrame(CAMetalLayer* layer) { void* layerBridged = (__bridge void*)layer; // Pass the CAMetalLayer to the emulator emulator->getRenderer()->setMTKLayer(layerBridged); // Runs the emulator for 1 frame and renders the output image using our layer emulator->runFrame(); } My MTKView delegate: class Renderer: NSObject, MTKViewDelegate { var parent: ContentView var device: MTLDevice! init(_ parent: ContentView) { self.parent = parent if let device = MTLCreateSystemDefaultDevice() { self.device = device } super.init() } func mtkView(_ view: MTKView, drawableSizeWillChange size: CGSize) {} func draw(in view: MTKView) { var metalLayer = view.layer as! CAMetalLayer // Run the emulator for 1 frame & display the output image iosRunFrame(metalLayer) } } Finally, the emulator's render function that interacts with the layer: void RendererMTL::setMTKLayer(void* layer) { metalLayer = (CA::MetalLayer*)layer; } void RendererMTL::display() { CA::MetalDrawable* drawable = metalLayer->nextDrawable(); if (!drawable) { return; } MTL::Texture* texture = drawable->texture(); <rest of rendering follows here using the drawable & its texture> } This is the Swift callstack at the time of the crash: To my understanding, I shouldn't be violating ARC rules as my bridging header uses CAMetalLayer* instead of void* and Swift will automatically account for ARC when passing CoreFoundation objects to Objective-C. However I don't have any other idea as to what might be causing this. I've been trying to debug this code for a couple of days without much success. If you need more info, the emulator code is also on Github Metal renderer: https://github.com/wheremyfoodat/Panda3DS/blob/ios/src/core/renderer_mtl/renderer_mtl.cpp#L58-L68 Bridge implementation: https://github.com/wheremyfoodat/Panda3DS/blob/ios/src/ios_driver.mm Bridging header: https://github.com/wheremyfoodat/Panda3DS/blob/ios/include/ios_driver.h Any help is more than appreciated. Thank you for your time in advance.
0
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449
Mar ’25
iPhone 16 Camera Control and AVCaptureSlider – Is there a way to detect which slider is active?
I am following the Apple sample code and trying to add a manual focus lens position slider: @available(iOS 18.0, *) private func addCameraControls() { if !self.session.controls.isEmpty { for control in self.session.controls { self.session.removeControl(control) } } self.cameraControlFocusSlider = nil //Focus Slider if self.videoDevice!.isLockingFocusWithCustomLensPositionSupported { self.cameraControlFocusSlider = AVCaptureSlider("Focus", symbolName: "dot.square", in: 0.0...1.0) self.cameraControlFocusSlider!.setActionQueue(self.sessionQueue) { focusValue in //Do manual focus } if self.session.canAddControl(self.cameraControlFocusSlider!) { self.session.addControl(self.cameraControlFocusSlider!) } } } So there are these AVCaptureSessionControlsDelegate methods: final func sessionControlsDidBecomeActive(_ session: AVCaptureSession) { print ("sessionControlsDidBecomeActive") } final func sessionControlsWillEnterFullscreenAppearance(_ session: AVCaptureSession) { print ("sessionControlsWillEnterFullscreenAppearance") } final func sessionControlsWillExitFullscreenAppearance(_ session: AVCaptureSession) { print ("sessionControlsWillExitFullscreenAppearance") } final func sessionControlsDidBecomeInactive(_ session: AVCaptureSession) { print ("sessionControlsDidBecomeInactive") } So when self.cameraControlFocusSlider is presented, I have to show the current value of the lense position. Lens position can change from auto focus and also from manual focus by the user using the app UI. Is there a way to see if self.cameraControlFocusSlider is active or being used? Please note that I will have more than one AVCaptureSlider in the final code.
0
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397
Mar ’25
Center the time in apps on Apple Watch app
Hi, I'll start by saying that I'm a new developer for apps for Apple devices, especially for Apple Watch, so please have mercy I'm trying to create an app for Apple Watch (WatchOs 10+) and I have a problem, my interface is made up of 3 buttons, one at the bottom of the screen and two smaller ones positioned on the top of the screen, each in their respective corners (one at the top right and the other at the top left). By positioning these buttons on the top of the screen, the top right button is covered by the default Apple time, and I would like to move it to the center, thus creating two side buttons and the time in the center. I'm also asking if there's a way to remove it since it's not useful to me, but reading some forums it seems that without it I don't pass the app verification, so I'm waiting for your advice. The only app I've seen in circulation on the app store that has the centered clock is petey.
3
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299
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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312
Mar ’25
Breakpoint issue: 'self cannot be reconstructed'
Hello! We're working on a large app with over 400 modules in both Swift and Objective-C, totaling more than 3 million lines of code. Since the release of Xcode 15 and 16 this summer, we’ve been experiencing issues with LLDB that have made debugging practically impossible. Here are some of the problems we’re facing: The first breakpoint takes a very long time to hit. When using 'po self', we encounter the following error: error: type for self cannot be reconstructed: type for typename "$s5MyModule10PlayerViewCD" was not found (cached) error: Couldn't realize Swift AST type of self. Hint: using `v` to directly inspect variables and fields may still work. We get numerous log messages like this: Debugging will be degraded due to missing types. Rebuilding the project will regenerate the needed module files.warning: (arm64) /Users/egormerkushev/Library/Developer/Xcode/DerivedData/App-enhtbwiyebmjsffoqkqhhpshsfia/Build/Products/Debug-iphoneos/MyModule.framework/MyModule(UploadConfiguration.o) 0x000000000000079d: unable to locate module needed for external types: /Users/builder/Library/Developer/Xcode/DerivedData/ModuleCache.noindex/169D1N0MIKBUI/Security-3BRN4UPIIGHME.pcm error: '/Users/builder/Library/Developer/Xcode/DerivedData/ModuleCache.noindex/169D1N0MIKBUI/Security-3BRN4UPIIGHME.pcm' does not exist In the Derived Data folder, we find files with hash-like names, such as: Security-3JM2E93YFDLZNYHWPPIMWNENB.d Security-3JM2E93YFDLZNYHWPPIMWNENB.dia Security-3JM2E93YFDLZNYHWPPIMWNENB.pcm Security-3JM2E93YFDLZNYHWPPIMWNENB.scan Security-3NAAT3MGN7XY96KVJW529HR41.d Security-3NAAT3MGN7XY96KVJW529HR41.dia Security-3NAAT3MGN7XY96KVJW529HR41.pcm Security-3NAAT3MGN7XY96KVJW529HR41.scan Security-3RJH8STJC01N1KKN7JCY1WK7F.d Security-3RJH8STJC01N1KKN7JCY1WK7F.dia Security-3RJH8STJC01N1KKN7JCY1WK7F.pcm Security-3RJH8STJC01N1KKN7JCY1WK7F.scan Security-3TILE9XTY0B8UV9VYL7Y0MJN.d Security-3TILE9XTY0B8UV9VYL7Y0MJN.dia Security-3TILE9XTY0B8UV9VYL7Y0MJN.pcm Security-3TILE9XTY0B8UV9VYL7Y0MJN.scan Security-3ZE8O6ZPHE4L52UZGL0PCBA59.d Security-3ZE8O6ZPHE4L52UZGL0PCBA59.dia ... When enabling LLDB logs with: log enable -f /tmp/lldb.log lldb all we end up with a 1.5GB log file containing hundreds of thousands of error messages. Finally, the LLDB console output in Xcode ends with errors like: error: Assertion failed: (byte_size > 0 && byte_size <= 8 && "GetMaxU64 invalid byte_size!"), function GetMaxU64, file DataExtractor.cpp, line 527 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 LLDB 0x0000000116ccfe1c llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) + 56 1 LLDB 0x000000011682fdcc lldb_private::lldb_assert(bool, char const*, char const*, char const*, unsigned int) + 148 2 LLDB 0x000000011682944c lldb_private::DataExtractor::GetMaxU64(unsigned long long*, unsigned long) const + 72 3 LLDB 0x00000001167335a8 lldb_private::CompilerType::GetValueAsScalar(lldb_private::DataExtractor const&, unsigned long long, unsigned long, lldb_private::Scalar&, lldb_private::ExecutionContextScope*) const + 304 4 LLDB 0x000000011666f0f4 lldb_private::Value::ResolveValue(lldb_private::ExecutionContext*, lldb_private::Module*) + 388 5 LLDB 0x0000000116671e94 lldb_private::ValueObject::ResolveValue(lldb_private::Scalar&) + 104 6 LLDB 0x0000000116674d6c lldb_private::ValueObject::GetValueAsSigned(long long, bool*) + 140 7 LLDB 0x000000011650510c lldb::SBValue::GetValueAsSigned(long long) + 160 8 lldb-rpc-server 0x00000001025ebe70 rpc_server::_ZN4lldb7SBValue16GetValueAsSignedEx::HandleRPCCall(rpc_common::Connection&, rpc_common::RPCStream&, rpc_common::RPCStream&) + 92 ... 13 libsystem_pthread.dylib 0x00000001917fb2e4 _pthread_start + 136 14 libsystem_pthread.dylib 0x00000001917f60fc thread_start + 8 Please file a bug report against lldb reporting this failure log, and as many details as possibleerror: Assertion failed: (byte_size > 0 && byte_size <= 8 && "GetMaxU64 invalid byte_size!"), function GetMaxU64, file DataExtractor.cpp, line 527 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 LLDB 0x0000000116ccfe1c llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) + 56 1 LLDB 0x000000011682fdcc lldb_private::lldb_assert(bool, char const*, char const*, char const*, unsigned int) + 148 2 LLDB 0x000000011682944c lldb_private::DataExtractor::GetMaxU64(unsigned long long*, unsigned long) const + 72 3 LLDB 0x00000001167335a8 lldb_private::CompilerType::GetValueAsScalar(lldb_private::DataExtractor const&, unsigned long long, unsigned long, lldb_private::Scalar&, lldb_private::ExecutionContextScope*) const + 304 4 LLDB 0x000000011666f0f4 lldb_private::Value::ResolveValue(lldb_private::ExecutionContext*, lldb_private::Module*) + 388 5 LLDB 0x0000000116671e94 lldb_private::ValueObject::ResolveValue(lldb_private::Scalar&) + 104 6 LLDB 0x0000000116674c44 lldb_private::ValueObject::GetValueAsUnsigned(unsigned long long, bool*) + 140 7 LLDB 0x0000000116505224 lldb::SBValue::GetValueAsUnsigned(unsigned long long) + 160 8 lldb-rpc-server 0x00000001025ebf18 rpc_server::_ZN4lldb7SBValue18GetValueAsUnsignedEy::HandleRPCCall(rpc_common::Connection&, rpc_common::RPCStream&, rpc_common::RPCStream&) + 92 9 lldb-rpc-server 0x00000001025f62b8 rpc_common::Connection::PrivateHandleRPCPacket(rpc_common::RPCPacket&, rpc_common::RPCPacket&, bool&) + 628 10 lldb-rpc-server 0x00000001025f9e8c Packets::ProcessPackets() + 564 11 lldb-rpc-server 0x00000001025f9bf4 Packets::ReadThread() + 276 12 lldb-rpc-server 0x00000001025f9ad4 Packets::RunReadThread(void*) + 12 13 libsystem_pthread.dylib 0x00000001917fb2e4 _pthread_start + 136 14 libsystem_pthread.dylib 0x00000001917f60fc thread_start + 8 Please file a bug report against lldb reporting this failure log, and as many details as possiblePrinting description of self: error: type for self cannot be reconstructed: type for typename "$s5MyModule10PlayerViewCD" was not found (cached) error: Couldn't realize Swift AST type of self. Hint: using `v` to directly inspect variables and fields may still work. In short, our debugger is completely unusable at this point, which is severely impacting our team's ability to develop effectively. Do you have any suggestions on how we can resolve these issues? We would really appreciate your help. Thank you!
11
29
5.6k
Mar ’25
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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Mar ’25
Rewrite `UNNotificationServiceExtension` sub class into Swift 6 async await notation
I'm trying to rewrite a Swift code to Swift 6 language mode and am stuck with this problem. How do I safely pass the bestAttemptContent and contentHandler to the Task? This is from the UNNotificationServiceExtension subclass. final class NotificationService: UNNotificationServiceExtension { var contentHandler: ((UNNotificationContent) -> Void)? var bestAttemptContent: UNMutableNotificationContent? var customNotificationTask: Task<Void, Error>? override func didReceive(_ request: UNNotificationRequest, withContentHandler contentHandler: @escaping (UNNotificationContent) -> Void) { self.contentHandler = contentHandler bestAttemptContent = (request.content.mutableCopy() as? UNMutableNotificationContent) guard let bestAttemptContent = bestAttemptContent else { invokeContentHandler(with: request.content) return } do { let notificationModel = try PushNotificationUserInfo(data: request.content.userInfo) guard let templatedImageUrl = notificationModel.templatedImageUrlString, let imageUrl = imageUrl(from: templatedImageUrl) else { invokeContentHandler(with: bestAttemptContent) return } setupCustomNotificationTask( imageUrl: imageUrl, bestAttemptContent: bestAttemptContent, contentHandler: contentHandler ) } catch { invokeContentHandler(with: bestAttemptContent) } } // More code private func downloadImageTask( imageUrl: URL, bestAttemptContent: UNMutableNotificationContent, contentHandler: @escaping (UNNotificationContent) -> Void ) { self.customNotificationTask = Task { let (location, _) = try await URLSession.shared.download(from: imageUrl) let desiredLocation = URL(fileURLWithPath: "\(location.path)\(imageUrl.lastPathComponent)") try FileManager.default.moveItem(at: location, to: desiredLocation) let attachment = try UNNotificationAttachment(identifier: imageUrl.absoluteString, url: desiredLocation, options: nil) bestAttemptContent.attachments = [attachment] contentHandler(bestAttemptContent) } } } I tried using the MainActor.run {}, but it just moved the error to that run function. The UNNotificationRequest is not sendable, and I don't think I can make it so. Wrap the setupCustomNotification in a Task will move the errors to the didReceive method. It seems like the consuming keyword will help here, but it leads to a compilation error, even with the latest Xcode (16.2). Any pointers?
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448
Mar ’25
Unexpected UINavigationController setViewControllers Behavior on iOS 18.2 During Animated Transitions
Hello everyone, I've run into a peculiar behavior with UINavigationController's setViewControllers on iOS 18.2 (I guess it might be reproducible on older versions) when reordering view controllers, and I wonder if anyone can shed some light on this issue. Initial State: The navigation stack is [A - B - C]. Without Animation: Setting [A - C - B] updates the stack to: A - C - B as expected. With Animation: Using the same command with animation changes the stack to [A - B], oddly omitting C. Has anyone else noticed similar behavior or knows why animations might disrupt the stack's update this way? I'd appreciate any insights or suggestions. Thanks, Dmytro
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335
Mar ’25
App Clip Closes Before SKOverlay Can Show “Open” Button When Live Activity Is Involved
I have an App Clip that uses SKOverlay.AppClipConfiguration to install the full app. Before I added a Live Activity call (Activity.request), the user could see “Install,” then “Open.” Now, once “Get” is tapped, the Clip immediately closes—no “Open” button appears. If I remove the Live Activity code, it works again. I’ve confirmed that parent/child entitlements match, and tested via TestFlight. Is there a known issue or recommended workaround for combining SKOverlay + Live Activities in an App Clip so it doesn’t dismiss prematurely? Any insights are appreciated! Note live activity is for App Clip only.
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265
Mar ’25
Crash When Previewing w/ Struct Binding Reassignment In Constructor
Platform Specs: Xcode 16.2 Swift 6.0.3 iOS 18.2 + iOS Simulator 18.3.1 Issue: Refer to the following code: struct CustomView: View { @Binding var prop: CustomStruct init(prop p: Binding<CustomStruct>) { _prop = p } init(isPreview: Bool) { let p = CustomStruct() _prop = .constant(p) } var body: some View { VStack { Text("hi") } } } #Preview { CustomView(isPreview: true) .preferredColorScheme(.dark) } The first constructor is for normal app functionality (and previews/functions correctly when used with the rest of the app in the ContentView preview tab). The second constructor is for previewing only CustomView in its own preview tab. This constructor does not work when previewing in the same file, as shown above. It triggers an ambiguous crash, stating that the diagnostic log (which obviously provides no clear information) should be checked. I have isolated the issue to be in the Binding reassignment in the second constructor. Replacing CustomStruct with anything but another struct, like an enum or primitive, fixes the issue. Note: This bug only occurs when previewing (either through the #Preview macro or PreviewProvider struct).
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289
Mar ’25
Changing instrument with AVMIDIControlChangeEvent bankSelect
I've been trying to use AVMIDIControlChangeEvent with a bankSelect message type to change the instrument the sequencer uses on a AVMusicTrack with no luck. I started with the Apple AVAEMixerSample, converting the initial setup/loading and portions dealing with the sequencer to Swift. I got that working and playing the "bluesyRiff" and then modified it to play individual notes. So my createAndSetupSequencer looked like func createAndSetupSequencer() { sequencer = AVAudioSequencer(audioEngine: engine) // guard let midiFileURL = Bundle.main.url(forResource: "bluesyRiff", withExtension: "mid") else { // print (" failed guard trying to get URL for bluesyRiff") // return // } let track = sequencer.createAndAppendTrack() var currTime = 1.0 for i: UInt32 in 0...8 { let newNoteEvent = AVMIDINoteEvent(channel: 0, key: 60+i, velocity: 64, duration: 2.0) track.addEvent(newNoteEvent, at: AVMusicTimeStamp(currTime)) currTime += 2.0 } The notes played, so then I also replaced the gs_instruments sound bank with GeneralUser GS MuseScore v1.442 first by trying guard let soundBankURL = Bundle.main.url(forResource: "GeneralUser GS MuseScore v1.442", withExtension: "sf2") else { return} do { try sampler.loadSoundBankInstrument(at: soundBankURL, program: 0x001C, bankMSB: 0x79, bankLSB: 0x08) } catch{.... } This appears to work, the instrument (8 which is "Funk Guitar") plays. If I change to bankLSB: 0x00 I get the "Palm Muted guitar". So I know that the soundfont has these instruments Stuff goes off the rails when I try to change the instruments in createAndSetupSequencer. Putting let programChange = AVMIDIProgramChangeEvent(channel: 0, programNumber: 0x001C) let bankChange = AVMIDIControlChangeEvent(channel: 0, messageType: AVMIDIControlChangeEvent.MessageType.bankSelect, value: 0x00) track.addEvent(programChange, at: AVMusicTimeStamp(1.0)) track.addEvent(bankChange, at: AVMusicTimeStamp(1.0)) just before my add note loop doesn't produce any change. Loading bankLSB 8 (Funk) in sampler.loadSoundBankInstrument and trying to change with bankSelect 0 (Palm muted) in createAndSetupSequencer results in instrument 8 (Funk) playing not Palm Muted. Loading bankLSB 0 (Palm muted) and trying to change with bankSelect 8 (Funk) doesn't work, 0 (Palm muted) plays I also tried sampler.loadInstrument(at: soundBankURL) and then I always get the first instrument in the sound font file (piano)no matter what values I put in my programChange/bankChange I've also changed the time in the track.addEvent to be 0, 1.0, 3.0 etc to no success The sampler.loadSoundBankInstrument specifies two UInt8 parameters, bankMSB and BankLSB while the AVMIDIControlChangeEvent bankSelect value is UInt32 suggesting it might be some combination of bankMSB and BankLSB. But the documentation makes no mention of what this should look like. I tried various combinations of 0x7908, 0X0879 etc to no avail I will also point out that I am able to successfully execute other control change events For example adding if i == 1 { let portamentoOnEvent = AVMIDIControlChangeEvent(channel: 0, messageType: AVMIDIControlChangeEvent.MessageType.portamento, value: 0xFF) track.addEvent(portamentoOnEvent, at: AVMusicTimeStamp(currTime)) let portamentoRateEvent = AVMIDIControlChangeEvent(channel: 0, messageType: AVMIDIControlChangeEvent.MessageType.portamentoTime, value: 64) track.addEvent(portamentoRateEvent, at: AVMusicTimeStamp(currTime)) } does produce a change in the sound. (As an aside, a definition of what portamento time is, other than "the rate of portamento" would be welcome. is it notes/seconds? freq/minute? beats/hour?) I was able to get the instrument to change in a different program using MusicPlayer and a series of MusicTrackNewMIDIChannelEvent on a track but these operate on a MusicTrack not the AVMusicTrack which the sequencer uses. Has anyone been successful in switching instruments through an AVMIDIControlChangeEvent or have any feedback on how to do this?
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328
Mar ’25