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
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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?
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
}
}
}
}
}
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
I can't find any simple c++ xcodeproj call to swift struct using modern c++ swift mix. there is the fibonacci example that is swift app call to c++.
Base on fibonacci example I create new simple project and fail to build it with error when I try to include #include <SwiftMixTester/SwiftMixTester-Swift.h>
What is wrong?
Is it the right place to ask this?
Any work project link?
Xcode 26.
Topic:
Programming Languages
SubTopic:
Swift
Error: "Attrubute can only be applied to types not declarations" on line 2 : @unchecked
@unchecked
enum ReminderRow : Hashable, Sendable {
case date
case notes
case time
case title
var imageName : String? {
switch self {
case .date: return "calendar.circle"
case .notes: return "square.and.pencil"
case .time: return "clock"
default : return nil
}
}
var image : UIImage? {
guard let imageName else { return nil }
let configuration = UIImage.SymbolConfiguration(textStyle: .headline)
return UIImage(systemName: imageName, withConfiguration: configuration)
}
var textStyle : UIFont.TextStyle {
switch self {
case .title : return .headline
default : return .subheadline
}
}
}
Hello,
I have integrated LZMA2 compression into my iOS app, Hogs, and successfully implemented compression. However, when attempting to upload the app for TestFlight, I encountered an error:
"The app references non-public symbols in Payload/Hogs.app/Hogs: _lzma_code, _lzma_end."
These functions are part of the LZMA compression library (specifically LZMA2). Here's a detailed description of the issue:
What I Have Done:
LZMA2 Integration: I integrated LZMA2 compression into the app and created a wrapper around the LZMA functions (_lzma_code, _lzma_end) to prevent direct references.
App Build Configuration:
I ensured the LZMA2 library is linked correctly with the -lzma flag in the linker settings.
I wrapped the LZMA functions in custom functions (my_lzma_code, my_lzma_end) in an attempt to avoid using the non-public symbols directly.
Error Message:
During the app submission process, I received the following error:
"The app references non-public symbols in Payload/Hogs.app/Hogs: _lzma_code, _lzma_end."
Steps Taken to Resolve:
Checked if any LZMA functions were exposed incorrectly.
Ensured that all non-public symbols were properly encapsulated in a wrapper.
Verified linker settings to ensure the proper inclusion of the LZMA2 library.
Request:
Could anyone provide suggestions or best practices to resolve this issue and avoid references to non-public symbols? Should I use a different method for linking LZMA2 or encapsulating these symbols?
Thank You:
I appreciate your help in resolving this issue so I can move forward with submitting the app for TestFlight.
Topic:
Programming Languages
SubTopic:
Swift
Tags:
Swift Packages
Apple Archive
Compression
TestFlight
Hi,
I am exploring Closures and trying to understand how they works. Closure have a special key feature that they can capture the context of the variables/constants from surroundings, once captured we can still use them inside the closure even if the scope in which they are defined does not exist.
I want to understand the lifecycle of captured variable/constant i.e., where are these captured variables stored and when these get created and destroyed.
How is memory managed for captured variables or constants in a closure, depending on whether they are value types or reference types?
Topic:
Programming Languages
SubTopic:
Swift
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!))
I recently submitted my app, Hogs, to the App Store, but it was rejected due to references to non-public symbols:
_lzma_code
_lzma_end
I am using the LZMA compression library in my app, and these functions are part of that implementation. Here's a breakdown of my usage:
Library Used: liblzma (custom wrapper around LZMA functions)
Error Message: "The app references non-public symbols in Payload/Hogs.app/Hogs: _lzma_code, _lzma_end."
Steps I’ve Taken:
I’ve wrapped the LZMA functions in my own functions (my_lzma_code, my_lzma_end) to prevent direct references.
I have checked the build settings and included -lzma in the linker flags.
I’ve tried using a custom framework to encapsulate LZMA, but the issue persists.
I would greatly appreciate any help or suggestions on how to resolve this issue and get my app approved. Is there any workaround or adjustment I can make to avoid using these non-public symbols?
Thank you in advance for your assistance.
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 & 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.
I am porting an old app from ObjC. The app uses many defined constants such as:
#define COM_OFFSET 12.5
and many variables that are read and/or written throughout the App, such as:
PCDate* Dates[367];
@class PCMainView;
PCMainView* MainView;
in one file called "PCCommon.h"
How do I duplicate this function in Swift? I have looked around and have found no help.
Thanks in advance.
No real intruduction for this, so I'll get to the point:
All this code is on GitHub: https://github.com/the-trumpeter/Timetaber-for-iWatch
But first, sorry;
/*
I got roasted,
last time I posted;
for not defining my stuff.
This'll be different,
but's gonna be rough;
'cuz there's lots and lots
to get through:
*/
//this is 'Timetaber Watch App/Define (No expressions)/Courses_vDef.swift' on the GitHub:
struct Course {
let name: String
let icon: String
let room: String
let colour: String
let listName: String
let listIcon: String
let joke: String
init(name: String, icon: String, room: String? = nil, colour: String,
listName: String? = nil, listIcon: String? = nil, joke: String? = nil)
{
self.name = name
self.icon = icon
self.room = room ?? "None"
self.colour = colour
self.listName = listName ?? name
self.listIcon = listIcon ?? (icon+".circle.fill")
self.joke = joke ?? ""
}
}
//this is 'Timetaber Watch App/TimeManager_fDef.swift' on the GitHub:
func getCurrentClass(date: Date) -> Array<Course> {
//returns the course in session depending on the input date
//it is VERY long but
//all you really need to know is what it returns:
//basically: return [rightNow, nextUp]
}
/*
I thought that poetry
would be okay,
But poorly thought things through:
For I'll probably find
that people online
will treat my rhymes like spew.
*/
So into the question:
I have a bunch of views, all (intendedly) watching two variables inside of a class:
//Github: 'Timetaber Watch App/TimetaberApp.swift'
class GlobalData: ObservableObject {
@Published var currentCourse: Course = getCurrentClass(date: .now)[0] // the current timetabled class in session.
@Published var nextCourse: Course = getCurrentClass(date: .now)[1] // the next timetabled class in session
}
...and a bunch of views using them in different ways as follows:
(Sorry, don't have the characters to define functions called in these)
import SwiftUI
//Github: 'Timetaber Watch App/Views/HomeView.swift'
struct HomeView: View {
@StateObject var data = GlobalData()
var body: some View {
//HERE:
let icon = data.currentCourse.icon
let name = data.currentCourse.name
let colour = data.currentCourse.colour
let room = roomOrBlank(course: data.currentCourse)
let next = data.nextCourse
VStack {
//CURRENT CLASS
Image(systemName: icon)
.foregroundColor(Color(colour))//add an SF symbol element
.imageScale(.large)
.font(.system(size: 25).weight(.semibold))
Text(name)
.font(.system(size:23).weight(.bold))
.foregroundColor(Color(colour))
.padding(.bottom, 0.1)
//ROOM
Text(room+"\n")
.multilineTextAlignment(.center)
.foregroundStyle(.gray)
.font(.system(size: 15))
if next.name != noSchool.name {
Spacer()
//NEXT CLASS
Text(nextPrefix(course: next))
.font(.system(size: 15))
Text(getNextString(course: next))
.font(.system(size: 15))
.multilineTextAlignment(.center)
}
}.padding()
}
}
// Github: 'Timetaber Watch App/Views/ListView.swift'
struct listTemplate: View {
@StateObject var data = GlobalData()
var listedCourse: Course = failCourse(feedback: "lT.12")
var courseTime: String = ""
init(course: Course, courseTime: String) {
self.courseTime = courseTime
self.listedCourse = course
}
var body: some View {
let localroom = if listedCourse.room == "None" {
"" } else { listedCourse.room }
let image = if listedCourse.listIcon == "custom1" {
Image(.paintbrushPointedCircleFill)
} else { Image(systemName: listedCourse.listIcon) }
HStack{
image
.foregroundColor(Color(listedCourse.colour))
.padding(.leading, 5)
Text(listedCourse.name)
.bold()
Spacer()
Text(courseTime)
Text(localroom).bold().padding(.trailing, 5)
}
.padding(.bottom, 1)
.background(data.currentCourse.name==listedCourse.name ? Color(listedCourse.colour).colorInvert(): nil) //HERE
}
}
struct listedDay: View {
let day: Dictionary<Int, Course>
var body: some View {
let dayKeys = Array(day.keys).sorted(by: <)
List {
ForEach((0...dayKeys.count-2), id: \.self) {
let num = $0
listTemplate(course: day[dayKeys[num]] ?? failCourse(feedback: "lD.53"), courseTime: time24toNormal(time24: dayKeys[num]))
}
}
}
}
struct ListView: View {
var body: some View {
if storage.shared.termRunningGB && weekdayFunc(inDate: .now) != 1
&& weekdayFunc(inDate: .now) != 7 {
ScrollView {
listedDay(
day: getTimetableDay(
isWeekA:
getIfWeekIsA_FromDateAndGhost(
originDate: .now,
ghostWeek: storage.shared.ghostWeekGB
),
weekDay: weekdayFunc(inDate: .now)
)
)
}
} else if !storage.shared.termRunningGB {
Text("There's no term running.\nThe day's classes will be displayed here.")
.multilineTextAlignment(.center)
.foregroundStyle(.gray)
.font(.system(size: 13))
} else {
Text("No school today.\nThe day's classes will be displayed here.")
.multilineTextAlignment(.center)
.foregroundStyle(.gray)
.font(.system(size: 13))
}
}
}
//There's one more view but I can't fit it for characters.
//On GitHub: 'Timetaber Watch App/Views/SettingsView.swift'
So...
THE FUNCTION:
This function is called when changes are made that will affect the correct output of getCurrentClass. It is intended to reload the views and the current/next variables to reflect those changes.\
//GHub: 'Timetaber Watch App/StorageManager.swift'
func reload() -> Void {
@ObservedObject var globalData: GlobalData //this line is erroring, I don't know how to fix it. Is this even the best/proper way to do this?
let courseData = getCurrentClass(date: .now)
globalData.currentCourse = courseData[0]
globalData.nextCourse = courseData[1]
//Variable '_globalData' used by function definition before being initialized
//that is the error appearing on those above two redefinitions.
print("Setup done\n")
}
Thanks!
-Gill
Hi,
I have a complex structure of classes, and I'm trying to migrate to swift6
For this classes I've a facade that creates the classes for me without disclosing their internals, only conforming to a known protocol
I think I've hit a hard wall in my knowledge of how the actors can exchange data between themselves. I've created a small piece of code that can trigger the error I've hit
import SwiftUI
import Observation
@globalActor
actor MyActor {
static let shared: some Actor = MyActor()
init() {
}
}
@MyActor
protocol ProtocolMyActor {
var value: String { get }
func set(value: String)
}
@MyActor
func make(value: String) -> ProtocolMyActor {
return ImplementationMyActor(value: value)
}
class ImplementationMyActor: ProtocolMyActor {
private(set) var value: String
init(value: String) {
self.value = value
}
func set(value: String) {
self.value = value
}
}
@MainActor
@Observable
class ViewObserver {
let implementation: ProtocolMyActor
var value: String
init() async {
let implementation = await make(value: "Ciao")
self.implementation = implementation
self.value = await implementation.value
}
func set(value: String) {
Task {
await implementation.set(value: value)
self.value = value
}
}
}
struct MyObservedView: View {
@State var model: ViewObserver?
var body: some View {
if let model {
Button("Loaded \(model.value)") {
model.set(value: ["A", "B", "C"].randomElement()!)
}
} else {
Text("Loading")
.task {
self.model = await ViewObserver()
}
}
}
}
The error
Non-sendable type 'any ProtocolMyActor' passed in implicitly asynchronous call to global actor 'MyActor'-isolated property 'value' cannot cross actor boundary
Occurs in the init on the line "self.value = await implementation.value"
I don't know which concurrency error happens... Yes the init is in the MainActor , but the ProtocolMyActor data can only be accessed in a MyActor queue, so no data races can happen... and each access in my ImplementationMyActor uses await, so I'm not reading or writing the object from a different actor, I just pass sendable values as parameter to a function of the object..
can anybody help me understand better this piece of concurrency problem?
Thanks
Hello,
I asked this question on 9th March but was asked to provide a project file and can't edit the original post. Please find the original question below and please find the new test project file at https://we.tl/t-fqAu8FrgUw.
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 the catch error "Error in JSON parsing"
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(newsFeed)
print(error)
}
catch{
print("Error in JSON parsing")
}
}
}
// Make the API Call
dataTask.resume()
}
And this is my Codable file NewsFeed.swift:
struct NewsFeed: Codable {
var id: String
var name: String
var country: String
var type: String
var overallrecsit: String
var dlastupd: String
var doverallrecsit: String
}
Please do you know why the parsing may be failing? Is it significant that in the debugging window the JSON is displaying backslashes before the quotation marks?
Thank you for any pointers :-)
Topic:
Programming Languages
SubTopic:
Swift
swift!!宇宙才是你的极限
谁能让它停下!!!
Topic:
Programming Languages
SubTopic:
Swift
Hello,
For the below code please can you tell me why the test code print("line 64") is being printed after the test code print("line 84") ? (i.e. how do I stop that happening?)
I would like the program to wait until the results array has been parsed before continuing the code (otherwise it does not have content to present).
I'm a bit confused why this is happening because I haven't written "async" anywhere.
import UIKit
struct NewsFeed: Codable {
var id: String
var name: String
var country: String
var type: String
var situation: String
var timestamp: String
}
class QuoteTableViewController: UITableViewController {
var newsFeed: [[String: String]] = []
override func tableView(_ tableView: UITableView, didSelectRowAt indexPath: IndexPath) {
// let selectedQuote = quotes[indexPath.row]
// performSegue(withIdentifier: "moveToQuoteDetail", sender: selectedQuote)
}
override func viewDidLoad() {
super.viewDidLoad()
// tableView.dataSource = self
}
// Uncomment the following line to preserve selection between presentations
// self.clearsSelectionOnViewWillAppear = false
// Uncomment the following line to display an Edit button in the navigation bar for this view controller.
// self.navigationItem.rightBarButtonItem = self.editButtonItem
// MARK: - Table view data source
override func numberOfSections(in tableView: UITableView) -> Int {
// #warning Incomplete implementation, return the number of sections
return 1
}
override func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
// (viewDidLoad loads after tableView)
// try getting array results here
let urlString = "https://www.notafunnyname.com/jsonmockup.php"
let url = URL(string: urlString)
let session = URLSession.shared
let dataTask = session.dataTask(with: url!) { (data, response, error) in
var dataString = String(data: data!, encoding: String.Encoding.utf8)
if error == nil && data != nil {
// Parse JSON
let decoder = JSONDecoder()
do {
var newsFeed = try decoder.decode([NewsFeed].self, from: data!)
print("line 64")
// print(newsFeed)
// print("line 125")
// print(newsFeed.count)
print(error)
}
catch{
print("Line 72, Error in JSON parsing")
print(error)
}
}
}
// Make the API Call
dataTask.resume()
// #warning Incomplete implementation, return the number of rows
print("line 84")
print(newsFeed.count)
return 10
}
override func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
// let cell = tableView.dequeueReusableCell(withIdentifier: "reuseIdentifier", for: indexPath)
let cell = UITableViewCell ()
cell.textLabel?.text = "test"
return cell
}
/*
// Override to support conditional editing of the table view.
override func tableView(_ tableView: UITableView, canEditRowAt indexPath: IndexPath) -> Bool {
// Return false if you do not want the specified item to be editable.
return true
}
*/
/*
// Override to support editing the table view.
override func tableView(_ tableView: UITableView, commit editingStyle: UITableViewCell.EditingStyle, forRowAt indexPath: IndexPath) {
if editingStyle == .delete {
// Delete the row from the data source
tableView.deleteRows(at: [indexPath], with: .fade)
} else if editingStyle == .insert {
// Create a new instance of the appropriate class, insert it into the array, and add a new row to the table view
}
}
*/
/*
// Override to support rearranging the table view.
override func tableView(_ tableView: UITableView, moveRowAt fromIndexPath: IndexPath, to: IndexPath) {
}
*/
/*
// Override to support conditional rearranging of the table view.
override func tableView(_ tableView: UITableView, canMoveRowAt indexPath: IndexPath) -> Bool {
// Return false if you do not want the item to be re-orderable.
return true
}
*/
// MARK: - Navigation
// In a storyboard-based application, you will often want to do a little preparation before navigation
override func prepare(for segue: UIStoryboardSegue, sender: Any?) {
// Get the new view controller using segue.destination.
// Pass the selected object to the new view controller.
// getPrice()
print("test_segue")
if let quoteViewController = segue.destination as? QuoteDetailViewController{
if let selectedQuote = sender as? String {
quoteViewController.title = selectedQuote
}
}
}
}
Many thanks
Topic:
Programming Languages
SubTopic:
Swift
I have the following TaskExecutor code in Swift 6 and is getting the following error:
//Error
Passing closure as a sending parameter risks causing data races between main actor-isolated code and concurrent execution of the closure.
May I know what is the best way to approach this?
This is the default code generated by Xcode when creating a Vision Pro App using Metal as the Immersive Renderer.
Renderer
@MainActor
static func startRenderLoop(_ layerRenderer: LayerRenderer, appModel: AppModel) {
Task(executorPreference: RendererTaskExecutor.shared) { //Error
let renderer = Renderer(layerRenderer, appModel: appModel)
await renderer.startARSession()
await renderer.renderLoop()
}
}
final class RendererTaskExecutor: TaskExecutor {
private let queue = DispatchQueue(label: "RenderThreadQueue", qos: .userInteractive)
func enqueue(_ job: UnownedJob) {
queue.async {
job.runSynchronously(on: self.asUnownedSerialExecutor())
}
}
func asUnownedSerialExecutor() -> UnownedTaskExecutor {
return UnownedTaskExecutor(ordinary: self)
}
static let shared: RendererTaskExecutor = RendererTaskExecutor()
}
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!
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?