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Odd Echo Output From Shell Script
I have a simple shell script as follows: #!/bin/bash OUTPUT="network.$(date +'%d-%m-%y').info.txt" SUPPORT_ID="email" echo "---------------------------------------------------" > $OUTPUT echo "Run date and time: $(date)" >> $OUTPUT echo "---------------------------------------------------" >> $OUTPUT ifconfig >> $OUTPUT echo "---------------------------------------------------" >> $OUTPUT echo "Network info written to file: $OUTPUT." echo "Please email this file to: $SUPPORT_ID." It just dumps the network config into a file. At some point I will have the file emailed out, but right now I'm just trying to figure out why the output looks like the following? bash ./test.sh .etwork info written to file: network.26-01-25.info.txt .lease email this file to: email Why in the world does the initial character of the last couple of "echo" commands get clipped and turned into periods? The echos for the output of the commands piped into the output file are fine. Strange... Any ideas?
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577
Jan ’25
NotificationCenter Crash On iOS 18+ Swift6.2
After switching our iOS app project from Swift 5 to Swift 6 and publishing an update, we started seeing a large number of crashes in Firebase Crashlytics. The crashes are triggered by NotificationCenter methods (post, addObserver, removeObserver) and show the following error: BUG IN CLIENT OF LIBDISPATCH: Assertion failed: Block was expected to execute on queue [com.apple.main-thread (0x1f9dc1580)] All scopes to related calls are already explicitly marked with @MainActor. This issue never occurred with Swift 5, but appeared immediately after moving to Swift 6. Has anyone else encountered this problem? Is there a known solution or workaround? Thanks in advance!
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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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540
Mar ’25
XCode not making bridging header file?
Hi, I'm trying to add Swift code to my Obj-C project. I've gone through all the tutorials and troubleshooting advice I can find online, no dice. I would appreciate any help, thank you so much in advance. I add a new swift file to my Obj-C project XCode offers to create a bridging header file for me, yes please New .swift file and .h file are added to my project no problem Header file shows up in build settings no problem I add a new class to my new swift file ("@objc class HelloPrinter: NSObject") When I build the app, nothing is generated in the bridging header file and the class is obviously inaccessible to my obj-c code Is this supposed to work? My understanding is that it's supposed to work. Somewhat concerning is the text that XCode puts in the bridging header file when it's created: "Use this file to import your target's public headers that you would like to expose to Swift." I don't want to use this bridging header file for anything. I want XCode to GENERATE STUFF in the bridging file. I also don't want to expose anything to Swift. I want the opposite to happen. So I don't get this text at all. Thanks in advance again.
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93
Apr ’25
Swift 6 concurrency. Apple Watch App target and -disable-dynamic-actor-isolation.
I've got a watch app, still with storyboard, WKInterfaceController and WatchConnectivity. After updating it for swift 6 concurrency I thought I'd keep it for a little while without swift 6 concurrency dynamic runtime check. So I added -disable-dynamic-actor-isolation in OTHER_SWIFT_FLAGS, but it doesn't seem to have an effect for the Apple Watch target. Without manually marking callbacks where needed with @Sendable in dynamic checks seem to be in place. swiftc invocation is as (includes -disable-dynamic-actor-isolation): swiftc -module-name GeoCameraWatchApp -Onone -enforce-exclusivity\=checked ... GeoCameraWatchApp.SwiftFileList -DDEBUG -enable-bridging-pch -disable-dynamic-actor-isolation -D DEBUG -enable-experimental-feature DebugDescriptionMacro -sdk /Applications/Xcode.app/Contents/Developer/Platforms/WatchOS.platform/Developer/SDKs/WatchOS11.2.sdk -target arm64_32-apple-watchos7.0 -g -module-cache-path /Users/stand/Library/Developer/Xcode/DerivedData/ModuleCache.noindex -Xfrontend -serialize-debugging-options -enable-testing -index-store-path /Users/stand/Library/Developer/Xcode/DerivedData/speedo-almhjmryctkitceaufvkvhkkfvdw/Index.noindex/DataStore -enable-experimental-feature OpaqueTypeErasure -Xcc -D_LIBCPP_HARDENING_MODE\=_LIBCPP_HARDENING_MODE_DEBUG -swift-version 6 ... -disable-dynamic-actor-isolation flag seems to be working for the iOS targets, I believe. The flag is described here Am I missing something? Should the flag work for both iOS and Apple Watch targets?
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639
Jan ’25
Compiler - method linking issue.
Issue: During app execution, the intended method is not being called; instead, the method preceding (written above the intended method) is being executed. For Example: //In my case the ViewController class is at 3rd level of inheritance. class ViewController: UIViewController { func methodA() { print("methodA") } func methodB() { print("methodB") } } let vc = ViewController() vc.methodB() Output: //"methodA" Expected: //"methodB" Observations: Recent code changes have revealed that enabling the below Swift-6 flag leads to this linking issue. When this flag is commented out, the problem disappears. .enableUpcomingFeature("InternalImportsByDefault") Additionally, moving the intended method into an extension of the same class resolves the issue when the flag is enabled. Conclusion: To resolve the issue: Comment out the Swift-6 flag. Alternatively, move the method into an extension of the same class, which addresses the issue for this specific case. I had similar issue in other class where it crashes with message "method not found", but actually the method is there. When moving the method into an extension of same class resolve this issue. Any help is much appreciated. Thanking you..
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May ’25
Apple Accelerate libSparse performance
I've created a Julia interface for Apple Accelerate's libSparse, via calling the library functions as if they were C (@ccall). I'm interested in using this in the context of power systems, where the sparse matrix is the Jacobian or the ABA matrix from a sparse grid network. However, I'm puzzled by the performance. I ran a sampling profiler on repeated in-place solves of Ax = b for a large sparse matrix A and random dense vectors b. (A is size 30k, positive definite so Cholesky factorization.) The 2 functions with the largest impact are _SparseConvertFromCoordinate_Double from libSparse.dylib, and BLASStateRelease from libBLAS.dylib. That strikes me as bizarre. This is an in-place solve: there should be minimal overheard from allocating/deallocating memory. Also, it seems strange that the library would repeatedly convert from coordinate form. Is this expected behavior? Thinking it might be an artifact of the Julia-C interface, I wrote up a similar program in C/Objective-C. I didn't profile it, but timing the same operation (repeated in-place solves of Ax = b for random vectors b, with the same matrix A as in the Julia) gave the same duration. I've attached the C/Objective-C below.profiling-comparison.m.txt If you're familiar with Julia, the following will give you the matrix I was working with: using PowerSystems, PowerNetworkMatrices sys = System("pglib_opf_case30000_goc.m") A = PowerNetworkMatrices.ABA_Matrix(sys).data where you can find the .m file here. (As a crude way to transfer A from Julia to C, I wrote the 3 arrays A.nzval, A.colptr, and A.rowval to .txt files as space-separated lists of numbers: the above C/objective-C reads in those files.) To duplicate my Julia profiling, do pkg> add AppleAccelerate#libSparse Profile--note the #libSparse part, these features aren't on the main branch--then run using AppleAccelerate, Profile # run previous code snippet to define A M, N = 10000, size(A)[1] bs = [rand(N) for _ in 1:M] aa_fact = AAFactorization(A) factor!(aa_fact) solve!(aa_fact, bs[1]) # pre-compile before we profile. Profile.init(n = 10^6, delay = 0.0003) @profile (for i in 1:M; solve!(aa_fact, bs[i]); end;) Profile.print(C = true, format = :flat, sortedby = :count)
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Jan ’25
Swift / C++ Interop with Storekit - actor isolated structure cannot be exported to C++
I can't find a viable path to call StoreKit from C++ right now and would love some ideas. I'm implementing the code exactly as shown at 4:09 in https://developer.apple.com/videos/play/wwdc2023/10172/ However when I add any StoreKit functionality in I immediately get "Actor isolated structure cannot be exposed in C++" This makes me think I can't create a StoreKit view and call it from C++? Am I missing a better way? I don't think I can have another structure that holds the storeChooser in it because it will have the same problem (I assume, although I will check). Part of the issue seems to be that my app is C++ so there is no main function called in the swift for me to open this view with either, I was going to use the present function Zoe described (as below). I've tried a lot of alternative approaches but it seems to be blocking async functions from showing in C++ as well. So I'm not sure how to access the basic product(for:) and purchase(product) functions. import Foundation import StoreKit import SwiftUI public struct storeChooser: View { public var productIDs: [String] public var fetchError: String //@State //Note this is from the UI @State public var products: [Product] = [] // @State private var isPresented = true // weak private var host: UIViewController? = nil public init() { productIDs = ["20_super_crystals_v1"] products = [] self.fetchError = "untried" } public var body: some View { VStack(spacing: 20) { Text( "Products") ForEach(self.products) { product in Button { //dont do anything yet } label: { Text("\(product.displayPrice) - \(product.displayName)") } } }.task { do { try await self.loadProducts() } catch { print(error) } } } public func queryProducts() { Task { do { try await self.loadProducts() } catch { print(error) } } } public func getProduct1Name() -> String { if self.products.count > 0 { return self.products[0].displayName } else { return "empty" } } private func loadProducts() async throws { self.products = try await Product.products(for: self.productIDs) } /* public mutating func present(_ viewController: UIViewController) { isPresented = true; let host = UIHostingController(rootView: self) host.rootView.host = host viewController.present(host, animated: true) } */ }
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May ’25
Calling StoreKit Swift from C++
What is the most obvious method of calling StoreKit from C++. I'm getting blocked by the fact that most of the critical StoreKit calls are async and functions marked a sync don't show up in the swift header for me to call from C++ (at least as far as I can tell). I'm trying to call let result = try await Product.products(for:productIDs) or let result = try await product.purchase() And C++ can't even see any functions I wrap these in as far as I can tell because i have to make them async. What am I missing? I tried a lot of alternates, like wrapping in Task { let result = try await Product.products(for:productIDs) } and it gives me 'Passing closure as a sending parameter' errors. Also when I try to call the same above code it gives me 'initializtion of immutable value never used' errors and the variables never appear. Code: struct storeChooser { public var productIDs: [String] public function checkProduct1 { Task { let result = try await Product.products(for: productIDs) } The above gives the initialization of immutable value skipped, and when I create a @State var products Then I get the 'passing closure as a sending parameter' error when i try to run it in a task it appears if I could make the function async and call it from C++ and have it return nothing it may work, does anyone know how to get C++ to see an async function in the -Swift.h file?
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May ’25
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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486
Oct ’25
json array shows in debugger but can't parse (corrected question)
Hello, Please see the test project at https://we.tl/t-aWAu7kk9lD 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 a catch error Line 57, Error in JSON parsing typeMismatch(Swift.Dictionary<Swift.String, Any>, Swift.DecodingError.Context(codingPath: [], debugDescription: "Expected to decode Dictionary<String, Any> but found an array instead.", underlyingError: nil)) 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("line 51") print(newsFeed) print(error) } catch{ print("Line 57, Error in JSON parsing") print(error) } } } // 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 situation: String var timestamp: String } Please do you know how to resolve the typeMismatch error?
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349
Mar ’25
SwiftData and 'NSKeyedUnarchiveFromData' should not be used to for un-archiving and will be removed in a future release
I get this red warning in Xcode every time my app is syncing to the iCloud. My model has only basic types and enum that conform to Codable so i'm not sure what is the problem. App is working well, synchronization works. But the warning doesn't look good. Maybe someone has idea how to debug it.
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926
Dec ’24
Swift Concurrency: Calling @MainActor Function from Protocol Implementation in Swift 6
I have a Settings class that conform to the TestProtocol. From the function of the protocol I need to call the setString function and this function needs to be on the MainActor. Is there a way of make this work in Swift6, without making the protocol functions running on @MainActor The calls are as follows: class Settings: TestProtocol{ var value:String = "" @MainActor func setString( _ string:String ){ value = string } func passString(string: String) { Task{ await setString(string) } } } protocol TestProtocol{ func passString( string:String ) }
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May ’25
Inquiry about WebRTC camera access when using Chrome browser and WKWebView API on iPadOS
We are Java application developers and we have a question regarding camera access via WebRTC on iPadOS. Specifically, on iPadOS 17.1, we are encountering an issue when trying to access the camera via the WKWebView API in the Chrome browser, where an error occurs and the camera capture fails. Our investigation suggests that device access through the navigator.mediaDevices property via the WKWebView API may not work in Chrome. However, it works as expected in the Safari browser, leading us to wonder if this is a Chrome-specific limitation, or if it's due to an iPadOS setting or specification. At this point, we are unsure if this issue is related to the WKWebView and WebRTC specifications on iPadOS 17.1, or if there are specific limitations in Chrome. We would appreciate any insights or solutions regarding camera access in iPadOS 17.1 with WKWebView and WebRTC, especially in relation to Chrome.
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597
Dec ’24
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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682
Jan ’25
Issue with Swift 6 migration issues
We are migrating to swift 6 from swift 5 using Xcode 16.2. we are getting below errors in almost each of our source code files : Call to main actor-isolated initializer 'init(storyboard:bundle:)' in a synchronous non isolated context Main actor-isolated property 'delegate' can not be mutated from a nonisolated context Call to main actor-isolated instance method 'register(cell:)' in a synchronous nonisolated context Call to main actor-isolated instance method 'setup()' in a synchronous nonisolated context Few questions related to these compile errors. Some of our functions arguments have default value set but swift 6 does not allow to set any default values. This requires a lot of code changes throughout the project. This would be lot of source code re-write. Using annotations like @uncheck sendable , @Sendable on the class (Main actor) name, lot of functions within those classes , having inside some code which coming from other classes which also showing main thread issue even we using @uncheck sendable. There are so many compile errors, we are still seeing other than what we have listed here. Fixing these compile errors throughout our project, would be like a re-write of our whole application, which would take lot of time. In order for us to migrate efficiently, we have few questions where we need your help with. Below are the questions. Are there any ways we can bypass these errors using any keywords or any other way possible? Can Swift 5 and Swift 6 co-exist? so, we can slowly migrate over a period of time.
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172
Jun ’25
Integrating App Clips in .NET MAUI iOS APP
We have an iOS App built in .NET MAUI (Multi-platform App UI). This is a web view App. We wish to integrate APP Clips into this App. But we are unable to do it, due to less available resources online on such implementation. We do not wish to share code between .NET MAUI App and App clips We understand it is not possible to add APP Clips without a parent swift/Xcode app. As an alternative solution we were thinking to Create a new APP in APP Store Connect using XCode/swift and integrate app clips to it. This parent app when downloaded by users will only redirect users to our MAIN .NET MAUI app to app store connect. We need to know if such apps will be approved by APPSTORE Connect? Please guide us on this Also please do let us know if you have any other solution to integrate App clips to a .NET MAUI App
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182
Jun ’25