Why Ternary operator in not called a binary Operator or ternary Operands ?
question ? answer1 : answer2
When it takes 2 operators ?
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Hi all,
I'm running into a Swift Concurrency issue and would appreciate some help understanding what's going on.
I have a protocol and an actor set up like this:
protocol PersistenceListener: AnyObject {
func persistenceDidUpdate(key: String, newValue: Any?)
}
actor Persistence {
func addListener(_ listener: PersistenceListener) {
listeners.add(listener)
}
/// Removes a listener.
func removeListener(_ listener: PersistenceListener) {
listeners.remove(listener)
}
// MARK: - Private Properties
private var listeners = NSHashTable<AnyObject>.weakObjects()
// MARK: - Private Methods
/// Notifies all registered listeners on the main actor.
private func notifyListeners(key: String, value: Any?) async {
let currentListeners = listeners.allObjects.compactMap { $0 as? PersistenceListener }
for listener in currentListeners {
await MainActor.run {
listener.persistenceDidUpdate(key: key, newValue: value)
}
}
}
}
When I compile this code, I get a concurrency error:
"Sending 'listener' risks causing data races"
I am encountering a strange issue. I have a class that manages a selection of generic items T in an Array. It's a work in progress, but I'l try to give a gist of the setup.
class FileManagerItemModel: NSObject, Identifiable, Codable, NSCopying, Transferable, NSItemProviderReading, NSItemProviderWriting {
var id: URL
static func == (lhs: FileManagerItemModel, rhs: FileManagerItemModel) -> Bool {
lhs.fileURL == rhs.fileURL
}
var fileURL: URL {
FileManagerItemModel.normalizedFileURL(type: type,
rootURL: rootURL,
filePath: filePath)
}
init(type: FileManagerItemType, rootURL: URL, fileURL: URL) {
self.type = type
self.rootURL = rootURL
self.filePath = FileManagerItemModel.filePathRelativeToRootURL(fileURL: fileURL, rootURL: rootURL) ?? "[unknown]"
self.id = FileManagerItemModel.normalizedFileURL(type: type,
rootURL: rootURL,
filePath: filePath)
}
}
The class that manages the selection of these FileManagerItemModels is like so:
@Observable
class MultiSelectDragDropCoordinator<T: Hashable>: ObservableObject, CustomDebugStringConvertible {
private(set) var multiSelectedItems: [T] = []
func addToSelection(_ item: T) {
if !multiSelectedItems.contains(where: { $0 == item }) {
multiSelectedItems.append(item)
}
}
...
}
My issue is that the check if !multiSelectedItems.contains(where: { $0 == item }) in func addToSelection fails. The if is always executed, even if multiSelectedItems contains the given item.
Now, my first thought would be to suspect the static func == check. But that check works fine and does what it should do. Equality is defined by the whole fileURL.
So, the if should have worked. And If I put a breakpoint in func addToSelection on the if, and type po multiSelectedItems.contains(where: { $0 == item }) in the debug console, it actually returns true if the item is in multiSelectedItems. And it properly return false if the item is not in multiSelectedItems.
Still, if I then continue stepping through the app after the breakpoint was hit and I confirmed that the contains should return true, the app still goes into the if, and adds a duplicate item.
I tried assigning to a variable, I tried using a function and returning the true/false. Nothing helps.
Does anyone have an idea on why the debugger shows one (the correct and expected) thing but the actual code still does something different?
Topic:
Programming Languages
SubTopic:
Swift
Everyone knows that dictionaries in swift are unordered collections, there is no problem with that.
I've noticed some behavior that I can't explain and hope someone can help me.
The first variant
We have a very simple code:
struct Test {
let dict = [1: “1”, 2: “2”, 3: “3”, 4: “4”, 5: “5”]
func test() {
for i in dict {
print(i)
}
}
}
If you call test() several times in a row, the output to the console on my computer looks something like this:
(key: 5, value: “5”)
(key: 1, value: “1”)
(key: 2, value: “2”)
(key: 3, value: “3”)
(key: 4, value: “4”)
(key: 2, value: “2”)
(key: 3, value: “3”)
(key: 1, value: “1”)
(key: 4, value: “4”)
(key: 5, value: “5”)
(key: 1, value: “1”)
(key: 3, value: “3”)
(key: 2, value: “2”)
(key: 5, value: “5”)
(key: 4, value: “4”)
At each new for loop we get a random order of elements
It seemed logical to me, because a dictionary is an unordered collection and this is correct behavior.
However
The second variant
the same code on my colleague's computer, but in the console we see something like this:
(key: 2, value: “2”)
(key: 3, value: “3”)
(key: 1, value: “1”)
(key: 4, value: “4”)
(key: 5, value: “5”)
(key: 2, value: “2”)
(key: 3, value: “3”)
(key: 1, value: “1”)
(key: 4, value: “4”)
(key: 5, value: “5”)
(key: 2, value: “2”)
(key: 3, value: “3”)
(key: 1, value: “1”)
(key: 4, value: “4”)
(key: 5, value: “5”)
always, within the same session, we get the same order in print(i)
We didn't use Playground, within which there may be differences, but a real project.
swift version 5+
we tested on Xcode 14+, 15+ (at first I thought it was because the first version had 14 and the second version had 15, but then a third colleague with Xcode 15 had the behavior from the first scenario)
we did a lot of checks, several dozens of times and always got that on one computer random output of items to the console, and in another case disordered only in the first output to the console
Thanks
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
I make some small program to make dots. Many of them.
I have a Generator which generates dots in a loop:
//reprat until all dots in frame
while !newDots.isEmpty {
virginDots = []
for newDot in newDots {
autoreleasepool{
virginDots.append(
contentsOf: newDot.addDots(in: size, allDots: &result, inSomeWay))
}
newDots = virginDots
}
counter += 1
print ("\(result.count) dots in \(counter) grnerations")
}
Sometimes this loop needs hours/days to finish (depend of inSomeWay settings), so it would be very nice to send partial result to a View, and/or if result is not satisfying — break this loop and start over.
My understanding of Tasks and Concurrency became worse each time I try to understand it, maybe it's my age, maybe language barier. For now, Button with {Task {...}} action doesn't removed Rainbow Wheel from my screen. Killing an app is wrong because killing is wrong.
How to deal with it?
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 came across a code
let myFruitBasket = ["apple":"red", "banana": "yellow", "budbeeri": "dark voilet", "chikoo": "brown"]
Can we have range for keys and values of dictionary, it will be convenient
for keys
print(myFruitBasket.keys[1...3])
// banana, budbeeri, chikoo
same for values
print(myFruitsBasket.values[1...3])
// yellow, voilet, brown
Is there a way to achieve the following using C++/Swift interoperability:
class MyCppClass
{
public:
...
...
private:
bool member1;
ACppClass member2;
ASwiftClass member3;
}
I'm aware of the recent C++/Objective-C interoperability compiler setting, but can't find any information on whether this is possible.
I've watched the Apple video:
https://developer.apple.com/videos/play/wwdc2023/10172/
and seen this post from Quinn:
https://developer.apple.com/forums/thread/768928
but I don't see anyone discussing this kind of situation.
Thanks in advance.
Topic:
Programming Languages
SubTopic:
Swift
Context: SwiftUI TextField with a String for simple math using NSExpression.
I first prepare the input string to an extent but a malformed input using valid characters still fails, as expected. Let's say preparedExpression is "5--"
let expr = NSExpression(format: preparedExpression)
gives
FAULT: NSInvalidArgumentException: Unable to parse the format string "5-- == 1"; (user info absent)
How can I use NSExpression such that either the preparedExpression is pre-tested before asking for actual execution or the error is handled in a polite way that I can use to alert the user to try again.
Is there a Swift alternative to NSExpression that I've missed?
Hello together,
since Xcode Version > 15 the following error handling causes following error "Pattern of type 'DecodingError' cannot match 'Never'
func getSupportedCountries() async {
// fetch all documents from collection "seasons" from firestore
let queryCountries = try? await db.collection("countries").getDocuments()
if queryCountries != nil {
self.countries = (queryCountries!.documents.compactMap({ (queryDocumentSnapshot) -> Country? in
let result = Result { try? queryDocumentSnapshot.data(as: Country.self) }
switch result {
case .success(let country):
if let country = country {
// A country value was successfully initialized from the DocumentSnapshot
self.errorMessage = nil
return country
}
else {
// A nil value was successfully initialized from the DocumentSnapshot,
// or the DocumentSnapshot was nil
self.errorMessage = "Document doesn't exist."
return nil
}
case .failure(let error):
// A Country value could not be initialized from the DocumentSnapshot
switch error {
case DecodingError.typeMismatch(_, let context):
self.errorMessage = "\(error.localizedDescription): \(context.debugDescription)"
case DecodingError.valueNotFound(_, let context):
self.errorMessage = "\(error.localizedDescription): \(context.debugDescription)"
case DecodingError.keyNotFound(_, let context):
self.errorMessage = "\(error.localizedDescription): \(context.debugDescription)"
case DecodingError.dataCorrupted(let key):
self.errorMessage = "\(error.localizedDescription): \(key)"
default:
self.errorMessage = "Error decoding document: \(error.localizedDescription)"
}
return nil
}
}))
} else {
self.errorMessage = "No documents in 'countries' collection"
return
}
}
the interesting part of the code where XCODE shows an error is from "switch error" downwards.
Does anyone of you have an idea what's wrong?
Ay help appreciated !
Thx, Peter
I have an @objC used for notification.
kTag is an Int constant, fieldBeingEdited is an Int variable.
The following code fails at compilation with error: Command CompileSwift failed with a nonzero exit code if I capture self (I edited code, to have minimal case)
@objc func keyboardDone(_ sender : UIButton) {
DispatchQueue.main.async { [self] () -> Void in
switch fieldBeingEdited {
case kTag : break
default : break
}
}
}
If I explicitly use self, it compiles, even with self captured:
@objc func keyboardDone(_ sender : UIButton) {
DispatchQueue.main.async { [self] () -> Void in
switch fieldBeingEdited { // <<-- no need for self here
case self.kTag : break // <<-- self here
default : break
}
}
}
This compiles as well:
@objc func keyboardDone(_ sender : UIButton) {
DispatchQueue.main.async { () -> Void in
switch self.fieldBeingEdited { // <<-- no need for self here
case self.kTag : break // <<-- self here
default : break
}
}
}
Is it a compiler bug or am I missing something ?
I'm using xcode 16.1 withSwift. I want to know how to call a function passing in an array. Also I need to know how to declare the function receiving the array. I currently have:
func myfunc(costa: [Double]) {
}
I call it like this:
myfunc(costa:[ ])
It's an array of Doubles. I don't get any errors but the array is always empty. Please help. Thank you.
Topic:
Programming Languages
SubTopic:
Swift
Just read about the new @concurrent option coming to Swift 6.2 and lover it, but...
It just me, but I which these options would pick a case and stick with it...
@Sendable
@unchecked
@MainActor
@concurrent
@Observable
@ObservationIgnored
Hi, I have issue on build my react native project and got this error "Undefined symbol: _swift_willThrowTypedImpl" how can I fix it?
Hello, I have an issue with importing some .mp3 files into a swift playground project (in Xcode, not in the Playground app). They worked fine in the Xcode project, but for some reason playgrounds isn't able to find them. I imported them the exact same way as I did in the Xcode project.
Does anyone know if there will be a Swift 6 version of "The Swift Programming Language" book and if so, when it will be released for Apple Books?
Topic:
Programming Languages
SubTopic:
Swift
When swizzling NSURLRequest initialiser and returning a mutable copy, the original instance does not get deallocated and eventually gets leaked and a crash follows after that.
Here's the swizzling setup:
static func swizzleInit() {
let initSel = NSSelectorFromString("initWithURL:cachePolicy:timeoutInterval:")
guard let initMethod = class_getInstanceMethod(NSClassFromString("NSURLRequest"), initSel) else {
return
}
let origInitImp = method_getImplementation(initMethod)
let block: @convention(block) (AnyObject, Any, NSURLRequest.CachePolicy, TimeInterval) -> NSURLRequest = { _self, url, policy, interval in
typealias OrigInit = @convention(c) (AnyObject, Selector, Any, NSURLRequest.CachePolicy, TimeInterval) -> NSURLRequest
let origFunc = unsafeBitCast(origInitImp, to: OrigInit.self)
let request = origFunc(_self, initSel, url, policy, interval)
return request.tagged()
}
let newImplementation = imp_implementationWithBlock(block as Any)
method_setImplementation(initMethod, newImplementation)
}
// create a mutable copy if needed and add a header
private func tagged() -> NSURLRequest {
guard let mutableRequest = self as? NSMutableURLRequest ?? self.mutableCopy() as? NSMutableURLRequest else {
return self
}
mutableRequest.setValue("test", forHTTPHeaderField: "test")
return mutableRequest
}
Then, we have a few test cases:
// memory leak and crash
func testSwizzleNSURLRequestInit() {
let request = NSURLRequest(url: URL(string: "https://example.com")!)
XCTAssertEqual(request.value(forHTTPHeaderField: "test"), "test")
}
// no crash, as the request is mutable, so no copy is created
func testSwizzleNSURLRequestInit2() {
let request = URLRequest(url: URL(string: "https://example.com")!)
XCTAssertEqual(request.value(forHTTPHeaderField: "test"), "test")
}
// no crash, as the request is mutable, so no copy is created
func testSwizzleNSURLRequestInit3() {
let request = NSMutableURLRequest(url: URL(string: "https://example.com")!)
XCTAssertEqual(request.value(forHTTPHeaderField: "test"), "test")
}
// no crash, as the new instance does not get deallocated
// when the test method completes (?)
var request: NSURLRequest?
func testSwizzleNSURLRequestInit4() {
request = NSURLRequest(url: URL(string: "https://example.com")!)
XCTAssertEqual(request?.value(forHTTPHeaderField: "test"), "test")
}
It appears a memory leak occurs only when any other instance except for the original one is being returned from the initialiser.
Is there a workaround to prevent the leak, while allowing for modifications of all requests?
Hello, everyone!
Help me please to find answer. I have two applications: App-1 with share extension and App-2 without it. From the second app I can open share extension via UIActivityViewController. But I need this extension in the second application to open immediately by pressing a button, and not through UIActivityViewController. Can I do this?
In my code I use a binding that use 2 methods to get and get a value. There is no problem with swift 5 but when I swift to swift 6 the compiler fails :
Here a sample example of code to reproduce the problem :
`import SwiftUI
struct ContentView: View {
@State private var isOn = false
var body: some View {
VStack {
Image(systemName: "globe")
.imageScale(.large)
.foregroundStyle(.tint)
Text("Hello, world!")
Toggle("change it", isOn: Binding(get: getValue, set: setValue(_:)))
}
.padding()
}
private func getValue() -> Bool {
isOn
}
private func setValue(_ value: Bool) {
isOn = value
}
}`
Xcode compiler log error :
1. Apple Swift version 6.1.2 (swiftlang-6.1.2.1.2 clang-1700.0.13.5) 2. Compiling with the current language version 3. While evaluating request IRGenRequest(IR Generation for file "/Users/xavierrouet/Developer/TestCompilBindingSwift6/TestCompilBindingSwift6/ContentView.swift") 4. While emitting IR SIL function "@$sSbScA_pSgIeAghyg_SbIeAghn_TR". for <<debugloc at "<compiler-generated>":0:0>>Stack dump without symbol names (ensure you have llvm-symbolizer in your PATH or set the environment var LLVM_SYMBOLIZER_PATH` to point to it):
0 swift-frontend 0x000000010910ae24 llvm::sys::PrintStackTrace(llvm::raw_ostream&, int) + 56
1 swift-frontend 0x0000000109108c5c llvm::sys::RunSignalHandlers() + 112
2 swift-frontend 0x000000010910b460 SignalHandler(int) + 360
3 libsystem_platform.dylib 0x0000000188e60624 _sigtramp + 56
4 libsystem_pthread.dylib 0x0000000188e2688c pthread_kill + 296
5 libsystem_c.dylib 0x0000000188d2fc60 abort + 124
6 swift-frontend 0x00000001032ff9a8 swift::DiagnosticHelper::~DiagnosticHelper() + 0
7 swift-frontend 0x000000010907a878 llvm::report_fatal_error(llvm::Twine const&, bool) + 280
8 swift-frontend 0x00000001090aef6c report_at_maximum_capacity(unsigned long) + 0
9 swift-frontend 0x00000001090aec7c llvm::SmallVectorBase::grow_pod(void*, unsigned long, unsigned long) + 384
10 swift-frontend 0x000000010339c418 (anonymous namespace)::SyncCallEmission::setArgs(swift::irgen::Explosion&, bool, swift::irgen::WitnessMetadata*) + 892
11 swift-frontend 0x00000001035f8104 (anonymous namespace)::IRGenSILFunction::visitFullApplySite(swift::FullApplySite) + 4792
12 swift-frontend 0x00000001035c876c (anonymous namespace)::IRGenSILFunction::visitSILBasicBlock(swift::SILBasicBlock*) + 2636
13 swift-frontend 0x00000001035c6614 (anonymous namespace)::IRGenSILFunction::emitSILFunction() + 15860
14 swift-frontend 0x00000001035c2368 swift::irgen::IRGenModule::emitSILFunction(swift::SILFunction*) + 2788
15 swift-frontend 0x00000001033e7c1c swift::irgen::IRGenerator::emitLazyDefinitions() + 5288
16 swift-frontend 0x0000000103573d6c swift::IRGenRequest::evaluate(swift::Evaluator&, swift::IRGenDescriptor) const + 4528
17 swift-frontend 0x00000001035c15c4 swift::SimpleRequest<swift::IRGenRequest, swift::GeneratedModule (swift::IRGenDescriptor), (swift::RequestFlags)17>::evaluateRequest(swift::IRGenRequest const&, swift::Evaluator&) + 180
18 swift-frontend 0x000000010357d1b0 swift::IRGenRequest::OutputType swift::Evaluator::getResultUncached<swift::IRGenRequest, swift::IRGenRequest::OutputType swift::evaluateOrFatalswift::IRGenRequest(swift::Evaluator&, swift::IRGenRequest)::'lambda'()>(swift::IRGenRequest const&, swift::IRGenRequest::OutputType swift::evaluateOrFatalswift::IRGenRequest(swift::Evaluator&, swift::IRGenRequest)::'lambda'()) + 812
19 swift-frontend 0x0000000103576910 swift::performIRGeneration(swift::FileUnit*, swift::IRGenOptions const&, swift::TBDGenOptions const&, std::__1::unique_ptr<swift::SILModule, std::__1::default_deleteswift::SILModule>, llvm::StringRef, swift::PrimarySpecificPaths const&, llvm::StringRef, llvm::GlobalVariable**) + 176
20 swift-frontend 0x0000000102f61af0 generateIR(swift::IRGenOptions const&, swift::TBDGenOptions const&, std::__1::unique_ptr<swift::SILModule, std::__1::default_deleteswift::SILModule>, swift::PrimarySpecificPaths const&, llvm::StringRef, llvm::PointerUnion<swift::ModuleDecl*, swift::SourceFile*>, llvm::GlobalVariable*&, llvm::ArrayRef<std::__1::basic_string<char, std::__1::char_traits, std::__1::allocator>>) + 156
21 swift-frontend 0x0000000102f5d07c performCompileStepsPostSILGen(swift::CompilerInstance&, std::__1::unique_ptr<swift::SILModule, std::__1::default_deleteswift::SILModule>, llvm::PointerUnion<swift::ModuleDecl*, swift::SourceFile*>, swift::PrimarySpecificPaths const&, int&, swift::FrontendObserver*) + 2108
22 swift-frontend 0x0000000102f5c0a8 swift::performCompileStepsPostSema(swift::CompilerInstance&, int&, swift::FrontendObserver*) + 1036
23 swift-frontend 0x0000000102f5f654 performCompile(swift::CompilerInstance&, int&, swift::FrontendObserver*) + 1764
24 swift-frontend 0x0000000102f5dfd8 swift::performFrontend(llvm::ArrayRef<char const*>, char const*, void*, swift::FrontendObserver*) + 3716
25 swift-frontend 0x0000000102ee20bc swift::mainEntry(int, char const**) + 5428
26 dyld 0x0000000188a86b98 start + 6076
Using Xcode 16.4 / Mac OS 16.4