I've been testing my open source libraries with Swift 6.2 and the new Default Actor Isolation concurrency build setting set to MainActor (with Complete strict concurrency turned on). My library Destinations uses protocols extensively, often applying conformance to foundational Swift protocols like Hashable and Identifiable. Many of these basic protocols are not flagged as running on the @MainActor in Beta 1, leading to situations like this:
Given this example code:
public protocol Contentable: Identifiable {
var id: UUID { get }
}
final class ContentModel: Contentable {
let id: UUID = UUID()
}
I get the warning:
Multiline
Conformance of 'ContentModel' to protocol 'Contentable' crosses into main actor-isolated code and can cause data races; this is an error in the Swift 6 language mode
The fix it suggests is to put a @MainActor before the Contentable protocol declaration in ContentModel, which seems to be a new attribute configuration in Swift 6.2. This solves the warning, but would create a lot of extra noise across the codebase.
Was it an oversight or a temporary omission that protocols like Hashable and Identifiable do not run on @MainActor by default, or is there some other reason they are excluded? Considering how often protocols in our code may conform to foundational protocols like this, it seems at odds to the MainActor mode of the Default Actor Isolation setting given that it was created to make concurrency easier and less boilerplate to implement.
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I’ve been struggling with this issue for a long time. When I try to archive my app to submit it to the App Store, I encounter two errors:
Linker command failed with exit code 1 (use -v to see invocation)
Linker command failed with exit code 1 (use -v to see invocation)
Topic:
Programming Languages
SubTopic:
Swift
I want to understand what the recommended way is for string interoperability between swift and c++. Below are the 3 ways to achieve it. Approach 2 is not allowed at work due to restrictions with using std libraries.
Approach 1:
In C++:
char arr[] = "C++ String";
void * cppstring = arr;
std::cout<<"before:"<<(char*)cppstring<<std::endl; // C++ String
// calling swift function and passing the void buffer to it, so that swift can update the buffer content
Module1::SwiftClass:: ReceiveString (cppstring, length);
std::cout<<"after:"<<(char*)cppstring<<std::endl; // SwiftStr
In Swift:
func ReceiveString (pBuffer : UnsafeMutableRawPointer , pSize : UInt ) -> Void
{
// to convert cpp-str to swift-str:
let swiftStr = String (cString: pBuffer.assumingMemoryBound(to: Int8.self));
print("pBuffer content: \(bufferAsString)");
// to modify cpp-str without converting:
let swiftstr:String = "SwiftStr"
_ = swiftstr.withCString { (cString: UnsafePointer<Int8>) in
pBuffer.initializeMemory(as: Int8.self, from: cString, count: swiftstr.count+1)
}
}
Approach 2:
The ‘String’ type returned from a swift function is received as ‘swift::String’ type in cpp. This is implicitly casted to std::string type. The std::string has the method available to convert it to char *.
void
TWCppClass::StringConversion ()
{
// GetSwiftString() is a swift call that returns swift::String which can be received in std::string type
std::string stdstr = Module1::SwiftClass::GetSwiftString ();
char * cstr = stdstr.data ();
const char * conststr= stdstr.c_str ();
}
Approach 3:
The swift::String type that is obtained from a swift function can be received in char * by directly casting the address of the swift::String. We cannot directly receive a swift::String into a char *.
void
TWCppClass::StringConversion ()
{
// GetSwiftString() is a swift call that returns swift::String
swift::String swiftstr = Module1::SwiftClass::GetSwiftString ();
// obtaining the address of swift string and casting it into char *
char * cstr = (char*)&swiftstr;
}
I am an SDK provider working with Swift Package Manager (SPM) to deliver libraries for iOS developers. My SDK currently uses SPM targets to modularize functionality. However, SPM enforces strict resource bundling, which prevents me from efficiently offering multiple targets—each with a different set of localization files—in a single package.
Current Limitation:
When multiple SPM targets share the same source and resource directory but require distinct sets of .lproj localization folders (for app size or client requirements), SPM raises “overlapping sources” errors. The only workaround is to manually split resource directories or have clients prune localizations post-build, which is inefficient and error-prone.
Feature Request:
Please consider adding native support in Swift Package Manager for:
Defining multiple targets within a single package that can process overlapping source/resource directories,
Each target specifying a distinct subset of localization resource files via the exclude or a new designated parameter,
Enabling efficient modular delivery of SDKs to clients needing different localization payloads, without redundant resource duplication or error-prone manual pruning.
Support for this feature would greatly ease SDK distribution, lower app sizes, and improve package maintainability for iOS and all Swift platforms.
Is anyone have this problem on xcode 26 ?
Undefined symbol: _swift_FORCE_LOAD$_swiftCompatibility50
Undefined symbol: _swift_FORCE_LOAD$_swiftCompatibility51
Undefined symbol: _swift_FORCE_LOAD$_swiftCompatibility56
Undefined symbol: _swift_FORCE_LOAD$_swiftCompatibilityConcurrency
Undefined symbol: _swift_FORCE_LOAD$_swiftCompatibilityDynamicReplacements
Hi, I've got this view model that will do a search using a database of keywords. It worked fine when the SearchEngine wasn't an actor but a regular class and the SearchResult wasn't a Sendable. But when I changed them, it returned Type of expression is ambiguous without a type annotation error at line 21 ( searchTask = Task {). What did I do wrong here? Thanks.
protocol SearchableEngine: Actor {
func searchOrSuggest(from query: String) -> SearchResult?
func setValidTitles(_ validTitles: [String])
}
@MainActor
final class SearchViewModel: ObservableObject {
@Published var showSuggestion: Bool = false
@Published var searchedTitles: [String] = []
@Published var suggestedKeyword: String? = nil
private var searchTask: Task<Void, Never>?
private let searchEngine: SearchableEngine
init(searchEngine: SearchableEngine) {
self.searchEngine = searchEngine
}
func search(_ text: String) {
searchTask?.cancel()
searchTask = Task {
guard !Task.isCancelled else { return }
let searchResult = await searchEngine.searchOrSuggest(from: text) ?? .notFound
guard !Task.isCancelled else { return }
await MainActor.run {
switch searchResult {
case let .searchItems(_, items):
showSuggestion = false
searchedTitles = items.map(\.title)
suggestedKeyword = nil
case let .suggestion(keyword, _, items):
showSuggestion = true
searchedTitles = items.map(\.title)
suggestedKeyword = keyword
case .notFound:
showSuggestion = false
searchedTitles = []
suggestedKeyword = nil
}
}
}
}
}
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.
Topic:
Programming Languages
SubTopic:
Swift
When i am trying to archive a framework for ML, using below command:
xcodebuild -workspace "./src/MLProject.xcworkspace" -configuration "Release" -sdk "iphoneos" -archivePath "./gen/out/Archives/Release-iphoneos/MLProject" -scheme "MLProject" -derivedDataPath "./gen/out/" archive BUILD_LIBRARY_FOR_DISTRIBUTION=YES SKIP_INSTALL=NO
The same command used to work fine on Xcode 16.4.
Attached is the detailed error
MLProject_Archive_failure.txt
So I’m writing a program, as a developer would - ‘with Xcode.’
Code produced an error.
The key values were swapped. The parameters suggested were ‘optional parameters variables.’
“var name: TYPE? = (default)”
var name0: TYPE
=============================
name0 = “super cool”
‘Name is not yet declared at this point
provided with
x - incorrect argument replace
ExampleStruct(name:”supercool”)
should be
x - incorrect argument replace
ExampleStruct(name0:”supercool”)
=============================
In swift, there is a procedural prioritization within the constructor calling process.
Application calls constructor.
Constructor provides constructor signature. Signature requires parameters & throws an error if the params are not in appropriate order. - “got it compiler; thank you, very much”
Typically, when this occurs, defaults will be suggested. Often the variable type. Ie String, Bool.
such as:
StructName(param1:Int64, param2:Bool)
(Recently, I have seen a decline in @Apple’s performance in many vectors.)
As stated before, the key value pairs were out of sequence. The optionals were suggested instead of the required parameters.
This leads me to believe that there is an order of operations in the calling procedure that is being mismanaged.
I.e. regular expression, matching with optional. This confuses these with [forced, required] parameters, and the mismanagement of ‘key: value’ pairs.
this is a superficial prognosis and would like to know if anyone has any insight as to why this may occur.
Could it be a configuration setting? Is it possibly the network I connected to bumped into something. Etc..
I appreciate any and all feedback.
Please take into consideration the Apple developer forum, guidelines before posting comments.
#dev_div
In trying to convert some Objective-C to Swift, I have a subclass of NSWindowController and want to write a convenience initializer. The documentation says
You can also implement an NSWindowController subclass to avoid requiring client code to get the corresponding nib’s filename and pass it to init(windowNibName:) or init(windowNibName:owner:) when instantiating the window controller. The best way to do this is to override windowNibName to return the nib’s filename and instantiate the window controller by passing nil to init(window:).
My attempt to do that looks like this:
class EdgeTab: NSWindowController
{
override var windowNibName: NSNib.Name? { "EdgeTab" }
required init?(coder: NSCoder)
{
super.init(coder: coder)
}
convenience init()
{
self.init( window: nil )
}
}
But I'm getting an error message saying "Incorrect argument label in call (have 'window:', expected 'coder:')". Why the heck is the compiler trying to use init(coder:) instead of init(window:)?
I want to use the Observations AsyncSequence on some SwiftData @Model instances to determine if internal calculations need to be done.
When a simple property is linked to the Observations it fires CONTINUOUSLY even though no change is made to the model property.
Also, when I try to observe a property which is a list of another @Model type the Observations sequence does not fire when I add or remove items.
I am hoping to use the async-algorithm's merge function so all the associated sequences can be combined since if any of the associated events should fire the calculation event.
I think that it would be helpful to have better interoperability between Swift and JavaScript. There are a lot of useful packages on NPM that don't have equivalents for Swift. It would be helpful if Apple provided easier ways to use NPM packages in a Swift project. Currently, the JavaScriptCore framework is missing many standard things used in many packages, like the fetch API. It would be helpful to be able to run sandboxed JavaScript code inside of a Swift app but allow access to specific domains, folders, etc., using a permissions system similar to Deno.
I am implementing the FFT using vDSP.DiscreteFourierTransform. According to the official documentation, the count parameter has requirements as outlined below:
/// The `count` parameter must be:
/// * For split-complex real-to-complex: `2ⁿ` or `f * 2ⁿ`, where `f` is `3`, `5`, or `15` and `n >= 4`.
/// * For split-complex complex-to-complex: `2ⁿ` or `f * 2ⁿ`, where `f` is `3`, `5`, or `15` and `n >= 3`.
/// * For interleaved: `f * 2ⁿ`, where `f` is `2`, `3`, `5`, `3x3`, `3x5`, or `5x5`, and `n>=2`.
Despite adhering to these specifications in theory, my attempt to initialize an interleaved DFT with count = 2 * 2 * 5 * 5 (equivalent to 5×5 × 2²) resulted in a failure. Below is the code snippet I used for the initialization:
do {
let dft = try vDSP.DiscreteFourierTransform(
previous: nil,
count: 2 * 2 * 5 * 5,
direction: .forward,
transformType: .complexReal,
ofType: DSPComplex.self
)
print(dft)
} catch {
print("DFT init failed:", error)
}
Could somebody more knowledgeable with these APIs have a look? Thanks!
Is there a swift6 manual that will teach me how to code in swift?
I’m aware that Xcode version 26 beta 3 provides an option to enable Swift’s Approachable Concurrency feature at the project level. However, I’d like to achieve the same for a Swift Package. Could you please advise on how to enable Approachable Concurrency support specifically for a Swift Package?
Is there any way to retrieve the memory pressure percentage using native libraries?
When I run the memory-pressure command, I can see the percentage of free memory, but I’d like to retrieve the same information using a native library.
Topic:
Programming Languages
SubTopic:
Swift
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!
I currently have a iOS app live on the App Store but I also want to release it on Android, the whole code is in Swift so would that be possible or would I have to rewrite my whole apps code in a different coding language.
We recently developed the provisional permission for our app, but we have noticed that is not working as expected in iOS 16 (We have tested only there).
Currently we request the permissions like this:
UNUserNotificationCenter.current().requestAuthorization(options: [.alert, .badge, .sound, .provisional]) { [weak self] _, _ in
// here we register for pushes in case authorizationStatus is provisional or authorised
}
What happens is we do get the 1st notification with the keep CTA - once tapped we see that there pops an action: "Deliver Immediately", but even though the user selects that, we still see under setting the pushes are marked as "Deliver Quietly".
In addition to this the sound and bage still stay as toggled off - and the lock screen and banner as well stay off.
Basically, nothing changes after the user selects "Deliver Immediately"
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.