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?
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Hi, I have issue on build my react native project and got this error "Undefined symbol: _swift_willThrowTypedImpl" how can I fix it?
Sometimes when my app crashes I get an exception like this: EXC_BREAKPOINT (SIGTRAP).
But I don't know how to catch it. Is there a way in Swift to catch such exceptions?
We developing Native App with C++17 for iOS. We override global new and delete operators. This App deallocate all allocated memories correctly by Run on Xcode (Command + R), but exception occurs launch from xcrun or App icon on iPhone.
I debugged the exception. Overriding new operation was called correctly, but overriding delete operation was not called. The default delete was called. I'm not sure why is that.
STEPS TO REPRODUCE
Build xcode project.
Run "xcrun devicectl device install app --device "
Run "xcrun devicectl device process launch --console --device "
PLATFORM AND VERSION
iOS
Development environment: Xcode 16.4, macOS macOS Sequoia 15.5
Run-time configuration: iOS 18.5
main.cpp I attached is sample code to reproduce this problem.
main.cpp
Topic:
Programming Languages
SubTopic:
General
I have a s hared library in C++ that was built with GNU Libtool, and I want to bundle it with my Swift app and call it from the app. How can I bundle it and call it?
i am trying to build my code and have ran into this error.
"Trailing closure passed to parameter of type 'DispatchWorkItem' that does not accept a closure"
i have been trying to figure it out for so long, and even ai cant figure it out. is this a bug, or am i missing some obvious way to fix this ?
func loadUser(uid: String, completion: (() -> Void)? = nil) {
db.collection("users").document(uid).getDocument { [weak self] snapshot, error in
guard let data = snapshot?.data(), error == nil else { completion?(); return }
DispatchQueue.main.async {
self?.currentUser = User(
username: data["username"] as? String ?? "Learner",
email: data["email"] as? String ?? "",
profileImageName: "person.circle.fill",
totalXP: data["totalXP"] as? Int ?? 0,
currentStreak: data["currentStreak"] as? Int ?? 0,
longestStreak: data["longestStreak"] as? Int ?? 0,
level: data["level"] as? Int ?? 1,
levelProgress: data["levelProgress"] as? Double ?? 0.0,
xpToNextLevel: data["xpToNextLevel"] as? Int ?? 100,
completedLessons: data["completedLessons"] as? [String] ?? []
)
self?.saveUser()
completion?()
}
}
}
I noticed that when I enter the fully immersive view and then click the X button below the window, the immersive space remains active, and the only way to dismiss it is to click the digital crown. On other apps (Disney+ for example), closing out of the main window while in immersive mode also closes out the immersive space. I tried applying an onDisappear modifier to the the Modules view with a dismissImmersiveSpace, but that doesn't appear to do anything.
Any help would be appreciated.
I’m working on a project in Xcode 16.2 and encountered an issue where getAPI() with a default implementation in a protocol extension doesn’t show up in autocomplete. Here’s a simplified version of the code:
import Foundation
public protocol Repository {
func getAPI(from url: String?)
}
extension Repository {
public func getAPI(from url: String? = "https://...") {
getAPI(from: url)
}
}
final class _Repository: Repository {
func getAPI(from url: String?) {
// Task...
}
}
let repo: Repository = _Repository()
repo.getAPI( // Autocomplete doesn't suggest getAPI()
I’ve tried the following without success:
• Clean build folder
• Restart Xcode
• Reindexing
Is there something wrong with the code, or is this a known issue with Xcode 16.2? I’d appreciate any insights or 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;
}
Module compiled with Swift 6.0.3 cannot be imported by the Swift 6.1 compiler: /private/var/tmp/_bazel_xx/8b7c61ad484d9da1bf94a11f12ae6ffd/rules_xcodeproj.noindex/build_output_base/execroot/main/CustomModules/BIYThred/CocoaLumberjack/framework/CocoaLumberjack.framework/Modules/CocoaLumberjack.swiftmodule/arm64-apple-ios.swiftmodule
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: $SUPPORT_ID."
It just dumps the network config into a file. At some point I will have the file emailed out, but right now I'm just trying to figure out why the output looks like the following?
bash ./test.sh
.etwork info written to file: network.26-01-25.info.txt
.lease email this file to: email
Why in the world does the initial character of the last couple of "echo" commands get clipped and turned into periods? The echos for the output of the commands piped into the output file are fine. Strange...
Any ideas?
Topic:
Programming Languages
SubTopic:
General
I have a simple shell script as follows:
#!/bin/bash
OUTPUT="network.$(date +'%d-%m-%y').info.txt"
SUPPORT_ID="emailaddress"
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: emailaddress
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?
Topic:
Programming Languages
SubTopic:
General
I’m stuck with repeated production crashes in my SwiftUI app and I can’t make sense of the traces on my own.
The symbolicated reports show the same pattern:
Crash on com.apple.CFNetwork.LoaderQ with EXC_BAD_ACCESS / PAC failure
Always deep in CFNetwork, most often in
URLConnectionLoader::loadWithWhatToDo(NSURLRequest*, _CFCachedURLResponse const*, long, URLConnectionLoader::WhatToDo)
No frames from my code, no sign of AuthManager or tokens.
What I’ve tried:
Enabled Address Sanitizer,
Malloc Scribble,
Guard Malloc,
Zombies.
Set CFNETWORK_DIAGNOSTICS=3 and collected Console logs.
Stress-tested the app (rapid typing, filter switching, background/foreground, poor network with Network Link Conditioner).
Could not reproduce the crash locally.
So far:
Logs show unrelated performance faults (I/O on main thread, CLLocationManager delegate), but no obvious CFNetwork misuse.
My suspicion is a URLSession lifetime or delegate/auth-challenge race, but I can’t confirm because I can’t trigger it.
Since starting this investigation, I also refactored some of my singletons into @State/@ObservedObject dependencies. For example, my app root now wires up AuthManager, BackendService, and AccountManager (where API calls happen using async/await) as @State properties:
@State var authManager: AuthManager
@State var accountManager: AccountManager
@State var backendService: BackendService
init() {
let authManager = AuthManager()
self._authManager = .init(wrappedValue: authManager)
let backendService = BackendService(authManager: authManager)
self._backendService = .init(wrappedValue: backendService)
self._accountManager = .init(wrappedValue: AccountManager(backendService: backendService))
}
I don’t know if this refactor is related to the crash, but I am including it to be complete.
Apologies that I don’t have a minimized sample project — this issue seems app-wide, and all I have are the crash logs.
Request:
Given the crash location (URLConnectionLoader::loadWithWhatToDo), can Apple provide guidance on known scenarios or misuses that can lead to this crash?
Is there a way to get more actionable diagnostics from CFNetwork beyond CFNETWORK_DIAGNOSTICS to pinpoint whether it’s session lifetime, cached response corruption, or auth/redirect?
Can you also confirm whether my dependency setup above could contribute to URLSession or backend lifetime issues?
I can’t reliably reproduce the crash, and without Apple’s insight the stack trace is effectively opaque to me.
Thanks for your time and help. Happy to send multiple symbolicated crash logs at request.
Thanks for any help.
PS. Including 2 of many similar crash logs. Can provide more if needed.
Atlans-2025-07-29-154915_symbolicated (cfloader).txt
Atlans-2025-08-08-124226_symbolicated (cfloader).txt
Greetings,
func stepForward(_ input: Int) -> Int {
return input + 1
}
func stepBackward(_ input: Int) -> Int {
return input - 1
}
func chooseStepFunction(backward: Bool) -> (Int) -> Int {
return backward ? stepBackward : stepForward /* Error
type of expression is ambiguous without a type annotation */
}
Why am I getting this error. If I change the function to
func chooseStepFunction(backward: Bool) -> (Int) -> Int {
if backward {
return stepBackward
else {
return stepForward
}
}
Why is the previous chooseStepFunction giving me an error ?
Thx in advance
I'm struggling to convert Swift 5 to Swift 6.
As advised in doc, I first turned strict concurrency ON. I got no error.
Then, selected swift6… and problems pop up.
I have a UIViewController with
IBOutlets: eg a TextField.
computed var eg duree
func using UNNotification: func userNotificationCenter
I get the following error in the declaration line of the func userNotificationCenter:
Main actor-isolated instance method 'userNotificationCenter(_:didReceive:withCompletionHandler:)' cannot be used to satisfy nonisolated requirement from protocol 'UNUserNotificationCenterDelegate'
So, I declared the func as non isolated.
This func calls another func func2, which I had also to declare non isolated.
Then I get error on the computed var used in func2
Main actor-isolated property 'duree' can not be referenced from a nonisolated context
So I declared duree as nonsilated(unsafe).
Now comes the tricky part.
The computed var references the IBOutlet dureeField
if dureeField.text == "X"
leading to the error
Main actor-isolated property 'dureeField' can not be referenced from a nonisolated context
So I finally declared the class as mainActor and the textField as nonisolated
@IBOutlet nonisolated(unsafe) weak var dureeField : UITextField!
That silences the error (but declaring unsafe means I get no extra robustness with swift6) just to create a new one when calling dureeField.text:
Main actor-isolated property 'text' can not be referenced from a nonisolated context
Question: how to address properties inside IBOutlets ? I do not see how to declare them non isolated and having to do it on each property of each IBOutlet would be impracticable.
The following did work, but will make code very verbose:
if MainActor.assumeIsolated({dureeField.text == "X"}) {
So I must be missing something.
I have a transformation function that takes in data, executes some instructions, and returns an output. This function is dynamic and not shipped with the binary. Currently, I’m executing it using JavaScriptCore.JSContext, which works well, but the function itself is written in JavaScript.
Is there a way to achieve something similar using Swift – such as executing a dynamic Swift script, either directly or through other means? I know this is possible on macOS, but I’m not sure about iOS. I’ve also heard that extensions might open up some possibilities here. Any insights or alternative approaches would be appreciated.
I have an old app that I just got a notice will be pulled form the App Store if I don't upgrade. I tried to open in Xcode but it says I need to use Xcode 10.1 to convert to Swift 4.
Exact message - "Use Xcode 10.1 to migrate the code to Swift 4."
I downloaded Xcode 10.1 , now the OS (Sequoia ) says can't do it, have to use the latest version of Xcode.
Exact message - "The version of Xcode installed on this Mac is not compatible with macOS Sequoia. Download the latest version for free from the App Store."
Any experience with this and suggestions would be greatly appreciated.
I've been searching all over the web trying to find the proper way to get all records created by a specific user in CloudKit.
I am able to get the correct id using:
guard let userRecordID = try? await container.userRecordID() else { return }
I can see that the id returned is associated with records in my CloudKit dashboard. So I would expect that the following would get those records:
let predicate = NSPredicate(format: "%K == %@", #keyPath(CKRecord.creatorUserRecordID), userRecordID)
let query = CKQuery(recordType: "CKUser", predicate: predicate)
But instead when I use that query it returns nothing. It is successful but with nothing returned...
Any ideas why this would be happening?
P.S. I have also tried constructing the predicate using the reference, but I get the same result - success with no results.
P.S.2 Also worth mentioning that I am trying to get the results from the public database and I have set my CKContainer to the correct container id.
I have my project running perfectly fine on Xcode 16. However, in Xcode 26 it doesn't build due to an error that I do not understand. I have three files that pertain to this error:
// FriendListResponse.swift
import Foundation
struct FriendListResponse: Decodable {
var friendships: [Friendship]
var collections: [FriendCollection]
}
// Friendship.swift
import Foundation
struct Friendship: Decodable {
var createdAt: String
var friendId: Int
var friendUserId: Int // user ID of the friend
var friendUsername: String
var id: Int
var tagNames: [String]
}
// FriendCollection.swift
struct FriendCollection: Decodable {
var id: Int
var permalink: String
var tagNames: [String]
var title: String
}
On the first file, FriendListResponse.swift, I am the simple error message "circular reference." I do not understand how these self-contained structs could create a circular reference. Although I have other data types in my project, none of them are even referenced in these files except for Friendship and FriendCollection.
The FriendListResponse is a struct that is created from JSON values that are fetched from an API. This is the function that fetches the JSON:
public static func listFriends(username: String) async throws -> [Friendship] {
let data = try await sendGETRequest(
url: "people/\(username)/friends/list.json"
)
print(String(data: data, encoding: .utf8)!)
let decoder = JSONDecoder()
decoder.keyDecodingStrategy = .convertFromSnakeCase
let wrapper = try decoder.decode(FriendListResponse.self, from: data)
return wrapper.friendships
}
// Note: the function sendGETRequest is just
// a function that I have created that takes a set
// of parameters and returns a data object
// using the HTTP GET protocol. I don't think
// that it is related to this issue. However, if you
// think that it is, I can share the code for that.
This error has also happened in a few other cases within contained networks of my data structure.
I do not know why this error is only appearing once I launch Xcode 26 beta with my project files. I would think that this error also would appear in Xcode 16.4.
Any help would be greatly appreciated in my process to compile my project on Xcode 26!