I’m working with Swift and encountered an issue when using the contains method on an array. The following code works fine: let result = ["hello", "world"].contains(Optional("hello")) // ✅ Works fine However, when I try to use the same contains method with the array declared in a separate constant(or variable), I get a compile-time error: let stringArray = ["hello", "world"] let result = stringArray.contains(Optional("hello")) // ❌ Compile-time error The compiler produces the following error message: Cannot convert value of type 'Optional<String>' to expected argument type 'String' Both examples seem conceptually similar, but the second one causes a compile-time error, while the first one works fine. This confuses me because I know that Swift automatically promotes a non-optional value to an optional when comparing it with an optional value. This means "hello" should be implicitly converted to Optional("hello") for the comparison. What I understand so far: The contains(_:) method is defined as: func contains(_ element: Element) -> Bool Internally, it calls contains(where:), as seen in the Swift source code: 🔗 Reference contains(where:) takes a closure that applies the == operator for comparison. Since Swift allows comparing String and String? directly (String is implicitly promoted to String? when compared with an optional), I expected contains(where:) to work the same way. My Questions: Why does the first example work, but the second one fails with a compile-time error? What exactly causes this error in the second case, even though both cases involve comparing an optional value with a non-optional value? Does contains(_:) behave differently when used with an explicit array variable rather than a direct array literal? If so, why? 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?

Hello, I was expecting the code below to print the test message "line 25" because the class "API" is being called on line 57. But "line 25" is not being displayed in the debug window, please could you tell me why? This is the debugging window: line 93 0 line 93 0 line 93 0 import UIKit // not sure these 2 below are needed import SwiftUI import Combine struct NewsFeed: Codable { var id: String var name: String var country: String var type: String var situation: String var timestamp: String } let urlString = "https://www.notafunnyname.com/jsonmockup.php" let url = URL(string: urlString) let session = URLSession.shared class API: ObservableObject { let dataTask = session.dataTask(with: url!) { (data, response, error) in print("line 25") 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 38") // print(newsFeed) // print("line 125") // print(newsFeed.count) print(error) } catch{ print("Line 46, Error in JSON parsing") print(error) } } }.resume // Make the API Call - not sure why but error clears if moved to line above // dataTask.resume() } let myAPIarray = API() 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) // #warning Incomplete implementation, return the number of rows print("line 93") 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 } } } }

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'm continuing with the migration towards Swift 6. Within one of our libraries, I want to check whether a parameter object: Any? confirms to Sendable. I tried the most obvious one: if let sendable = object as? Sendable { } But that results into the compiler error "Marker protocol 'Sendable' cannot be used in a conditional cast". Is there an other way to do this?

When I run app, it works on iOS16+ device. But when I run on iOS15 device just working on debug mode, if I run release or profile modeI got runtime error: Log: (lldb) dyld[4928]: Symbol not found: (_objc_claimAutoreleasedReturnValue) Referenced from: '/private/var/containers/Bundle/Application/C724D7C6-82FA-4AF3-AE83-EC035B4429A5/Runner.app/Frameworks/geolocator_apple.framework/geolocator_apple' Expected in: '/usr/lib/libobjc.A.dylib' thread #1, stop reason = signal SIGABRT frame #0: 0x0000000106cbb2cc dyld`__abort_with_payload + 8 dyld`__abort_with_payload: -&amp;gt; 0x106cbb2cc &amp;lt;+8&amp;gt;: b.lo 0x106cbb2e8 ; &amp;lt;+36&amp;gt; 0x106cbb2d0 &amp;lt;+12&amp;gt;: stp x29, x30, [sp, #-0x10]! 0x106cbb2d4 &amp;lt;+16&amp;gt;: mov x29, sp 0x106cbb2d8 &amp;lt;+20&amp;gt;: bl 0x106c8164c ; cerror_nocancel Target 0: (Runner) stopped. Flutter doctor : Doctor summary (to see all details, run flutter doctor -v): [✓] Flutter (Channel stable, 3.29.2, on macOS 15.2 24C101 darwin-arm64, locale en-VN) [✓] Android toolchain - develop for Android devices (Android SDK version 34.0.0) [✓] Xcode - develop for iOS and macOS (Xcode 16.2) [✓] Chrome - develop for the web [✓] Android Studio (version 2024.2) [✓] VS Code (version 1.97.2)

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