I’m working with Swift and ran into an issue when using the contains(_:) method on an array. The following code works fine: let result = ["hello", "world"].contains(Optional("hello")) // ✅ Works fine But when I try to use the same contains method with the array declared in a separate variable, I get a compile-time error: let stringArray = ["hello", "world"] let result = stringArray.contains(Optional("hello")) // ❌ Compile-time error Both examples seem conceptually similar, but the second one causes a compile-time error, while the first one works fine. I understand that when comparing an optional value (Optional("hello")) with a non-optional value ("hello"), Swift automatically promotes the non-optional value to an optional (i.e., "hello" becomes Optional("hello")). 🔗 reference What I don’t understand is why the first code works but the second one doesn’t, even though both cases involve comparing an optional value with a non-optional value. I know that there are different ways to resolve this, like using nil coalescing or optional binding, but what I’m really looking for is a detailed explanation of why this issue occurs at the compile-time level. Can anyone explain the underlying reason for this behavior?

I am a Chinese student beginner ,do you have any advice for me to learn swift？I don't know how to start it.Please!🙏

Hi Apple Developer Community, I'm facing a crash when updating an array of tuples from both a background thread and the main thread simultaneously. Here's a simplified version of the code in a macOS app using AppKit: class ViewController: NSViewController { var mainthreadButton = NSButton(title: "test", target: self, action: nil) var numbers = Array(repeating: (dim: Int, key: String)(0, "default"), count: 1000) override func viewDidLoad() { super.viewDidLoad() view.addSubview(mainthreadButton) mainthreadButton.translatesAutoresizingMaskIntoConstraints = false mainthreadButton.centerXAnchor.constraint(equalTo: view.centerXAnchor).isActive = true mainthreadButton.centerYAnchor.constraint(equalTo: view.centerYAnchor).isActive = true mainthreadButton.widthAnchor.constraint(equalToConstant: 100).isActive = true mainthreadButton.heightAnchor.constraint(equalToConstant: 100).isActive = true mainthreadButton.target = self mainthreadButton.action = #selector(arraytest(_:)) } @objc func arraytest(_ sender: NSButton) { print("array update started") // Background update DispatchQueue.global().async { for i in 0..<1000 { self.numbers[i].dim = i } } // Main thread update var sum = 0 for i in 0..<1000 { numbers[i].dim = i + 1 sum += numbers[i].dim print("test \(sum)") } mainthreadButton.title = "test = \(sum)" } } This results in a crash with the following message: malloc: double free for ptr 0x136040c00 malloc: *** set a breakpoint in malloc_error_break to debug What's interesting: This crash only happens when the tuple contains a String ((dim: Int, key: String)) If I change the tuple type to use two Int values ((dim: Int, key: Int)), the crash does not occur My Questions: Why does mutating an array of tuples containing a String crash when accessed from multiple threads? Why is the crash avoided when the tuple contains only primitive types like Int? Is there an underlying memory management issue with value types containing reference types like String? Any explanation about this behavior and best practices for thread-safe mutation of such arrays would be much appreciated. Thanks in advance!

and yeah, swift vaguely is reminiscent of a programming language I developed, but I want swift To do return if (var blah:Int32 == 43){ blah = blah2; } your welcome !! thank me on my new accounting job lol =/ basically I want to return conditional statements for a private reason

Hi There, I have a iOS App which has been published and purely managing data by SwiftData. I use following simple codes everywhere in Views: ... @Query var items: [Item] .... if let firstItem = items.first( where: {...}) { ... Then I encountered crash at Query that _items.wrapperdValue has some errors. Then I tried to split first(where...) into ordinary way: let filteredItems = items.filter(...) if let firstItem = filteredItems.first { ... It runs OK. Is it a bug in SwiftData in 18.2 or I missed some steps to facilitate SwiftData macros?

Is it ok for an Actor type to have a Publisher as a property to let others observe changes over time? Or use the @Published property wrapper to achieve this? actor MyActor { var publisher = PassthroughSubject<Int, Never>() var data: Int { didSet { publisher.send(data) } } ... } // Usage var tasks = Set<AnyCancellable>() let actor = MyActor() Task { let publisher = await actor.publisher publisher.sink { print($0) }.store(in: &tasks) } This seems like this should be acceptable. I would expect a Publisher to be thread safe, and as long as the Output is a value type things should be fine. I have been getting random EXC_BAD_ACCESS errors when using this approach. But turning on the address sanitizer causes these crashes to go away. I know that isn't very specific but I wanted to start by seeing if this type of pattern is ok to do.

I've narrowed down my question after many rabbit holes - how can C++ code open any view in Swift. I can call functions in swift from C++ (works great), but not async or main actor (or actor at all) functions. And if I'm not mistaken all views are actors if not main actors? When calling from C+ I think its necessary that the first view be the main actor? I've implemented the code from the WWDC23 C++ interop video (Zoe's image picker) where I made a view in a struct, and just want to call it and let the view do the work. The compiler immediately gives me 'cannot expose main actors to C++'. If I'm not mistaken, doesn't this block the opening of any kind of swift view from C++? Hopefully I'm missing something obvious, which is likely :) In Zoe's code was his entry point into the program still Swift and not actually C++ app? Thanks! Thanks!

When i create a intance of swift String : Let str = String ("Hello") As swift String are immutable, and when we mutate the value of these like: str = "Hello world ......." // 200 characters Swift should internally allocate new memory and copy the content to that buffer for update . But when i checked the addresses of original and modified str, both are same? Can you help me understand how this allocation and mutation working internally in swift String?

I am currently encountering two deprecated errors in my code. Could someone please identify the issues with the code? Errors: 'init(coordinateRegion:interactionModes:showsUserLocation:userTrackingMode:annotationItems:annotationContent:)' was deprecated in iOS 17.0: Use Map initializers that take a MapContentBuilder instead. 'MapAnnotation' was deprecated in iOS 17.0: Use Annotation along with Map initializers that take a MapContentBuilder instead. Code: // MARK: - Stores Map (Dynamic) struct StoresMapView: View { @State private var storeLocations: [StoreLocation] = [] @State private var region = MKCoordinateRegion( center: CLLocationCoordinate2D(latitude: -31.95, longitude: 115.86), span: MKCoordinateSpan(latitudeDelta: 0.5, longitudeDelta: 0.5) ) var body: some View { Map(coordinateRegion: $region, interactionModes: .all, annotationItems: storeLocations) { store in MapAnnotation(coordinate: CLLocationCoordinate2D(latitude: store.latitude, longitude: store.longitude)) { VStack(spacing: 4) { Image(systemName: "leaf.circle.fill") .font(.title) .foregroundColor(.green) Text(store.name) .font(.caption) .fixedSize() } } } .onAppear(perform: loadStoreData) .navigationTitle("Store Locator") } private func loadStoreData() { guard let url = URL(string: "https://example.com/cop092/StoreLocations.json") else { return } URLSession.shared.dataTask(with: url) { data, _, _ in if let data = data, let decoded = try? JSONDecoder().decode([StoreLocation].self, from: data) { DispatchQueue.main.async { self.storeLocations = decoded if let first = decoded.first { self.region.center = CLLocationCoordinate2D(latitude: first.latitude, longitude: first.longitude) } } } }.resume() } }

Is there any way to use metal-cpp in a Swift project? I have a platform layer I've written in Swift that handles Window/View creation, as well as event handling, etc. I've been trying to bridge this layer with my C++ layer as you normally would using a pure C interface, but using Metal instances that cross this boundary just doesn't seem to work. e.g. Currently I initialize a CAMetalLayer for my NSView, setting that as the layer for the view. I've tried passing this Metal layer into my C++ code via a void* pointer through a C interface, and then casting it to a CA::MetalView to be used. When this didn't work, I tried creating the CA::MetalLayer in C++ and passing that back to the Swift layer as a void* pointer, then binding it to a CAMetalLayer type. And of course, this didn't work either. So are the options for metal-cpp to use either Objective-C or just pure C++ (using AppKit.hpp)? Or am I missing something for how to integrate with Swift?

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 ) }

Hi, I'm relatively new to iOS development and kindly ask for some feedback on a strategy to achieve this desired behavior in my app. My Question: What would be the best strategy for sound effect playback when an app is in the background with precise timing? Is this even possible? Context: I created a basic countdown timer app (targeting iOS 17 with Swift/SwiftUI.). Countdown sessions can last up to 30-60 mins. When the timer is started it progresses through a series of sub-intervals and plays a short sound for each one. I used AVAudioPlayer and everything works fine when the app is in the foreground. I'm considering switching to AVAudioEngine b/c precise timing is very important and the AIs tell me this would have better precision. I'm already setting "App plays audio or streams audio/video using AirPlay" in my Plist, and have configured: AVAudioSession.sharedInstance().setCategory(.playback, mode: .default, options: .mixWithOthers) Curiously, when testing on my iPhone 13 mini, sounds sometimes still play when the app is in the background, but not always. What I've considered: Background Tasks: Would they make any sense for this use-case? Seems like not if the allowed time is short &amp; limited by the system. Pre-scheduling all Sounds: Not sure this would even work and seems like a lot of memory would be needed (could be hundreds of intervals). ActivityKit Alerts: works but with a ~50ms delay which is too long for my purposes. Pre-Render all SFX to 1 large audio file: Seems like a lot of work and processing time and probably not worth it. I hope there's a better solution. I'd really appreciate any feedback.

As I migrate my apps to Swift 6 one by one, I am gaining a deeper understanding of concurrency. In the process, I am quite satisfied to see the performance benefits of parallel programming being integrated into my apps. At the same time, I have come to think that actor is a great type for addressing the 'data race' issues that can arise when using the 'singleton' pattern with class. Specifically, by using actor, you no longer need to write code like private let lock = DispatchQueue(label: "com.singleton.lock") to prevent data races that you would normally have to deal with when creating a singleton with a class. It reduces the risk of developer mistakes. import EventKit actor EKDataStore: Sendable { static let shared = EKDataStore() let eventStore: EKEventStore private init() { self.eventStore = EKEventStore() } } Of course, since a singleton is an object used globally, it can become harder to manage dependencies over time. There's also the downside of not being able to inject dependencies, which makes testing more difficult. I still think the singleton pattern is ideal for objects that need to be maintained throughout the entire lifecycle of the app with only one instance. The EKDataStore example I gave is such an object. I’d love to hear other iOS developers' opinions, and I would appreciate any advice on whether I might be missing something 🙏

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.

Is there any way that I can import a Java module for use from Swift?

I'm encountering an issue where certain images are not displaying on some iOS devices, while the same code works perfectly on others. There’s no error or crash — just some images fail to load or display. I've confirmed the image URLs and formats are correct. Has anyone faced a similar issue or could suggest what might be causing this inconsistent behavior? Thanks in advance!

谁能告诉我为什么？ “[正在运行] swift ”d：\vscode object\swift object\ceshi.swift” JIT 会话错误：未找到符号：[ $ss 27_allocateUninitializedArrayySayxG_BptBwlFyp_Tg5 ] 未能具体化符号： { （main， { main， $sSa 12_endMutationyyF， $ss 5print_9separator10terminatoryypd_S2StFfA0_， $ss 5print_9separator10terminatoryypd_S2StFfA1_， $ss 27_finalizeUninitializedArrayySayxGABnlF }） } [完成] 在 0.47 秒内退出并带有 code=4294967295” 当“Swift for Windows”在 VSCode for Windows 上运行时。 路径为 true，“Package-swift-lsp： Path”为 true。 谁能告诉我为什么？

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!

With Swift being brought to new places, is anyone working on interoperability with PHP? I'd love to replace much of my PHP and Javascript web code with Swift (and ideally SwiftUI for UI design). Are there any projects/people working in this space?

Hey everyone, I have a problem with an app im creating. The code doesn't have any errors but the console has this that pops up: Snapshot request 0x1054191d0 complete with error: <NSError: 0x10541a970; domain: FBSSceneSnapshotErrorDomain; code: 4; "an unrelated condition or state was not satisfied"> { NSLocalizedDescription = an error occurred during a scene snapshotting operation; }