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;
}
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I'm developing an audio unit for use on iOS. The AUv3 worked fine with xcode 15.X and swift 5.X. I recently tried to submit an update to my plug-in but Apple refused submission because my Xcode was not the latest. Now that I'm on Xcode 16.4 I can't get my project to compile, even when following all of the same previous steps.
As one example of a change, Xcode doesn't appear to include the “C++ and Objective-C interoperability” build setting that it used to. This setting is noted in the Swift documentation and I used to need it, https://www.swift.org/documentation/cxx-interop/project-build-setup/#mixing-swift-and-c-using-xcode
Currently my C++ code can't see anything from Swift, and I get a "Use of undeclared identifier 'project_name'". I've selected Switch support for version 5.0 in an attempt to minimize changes from Apple.
My process is I generate an Xcode project file from my audio plugin support, JUCE. Then I add in the swift files, click yes to create bridging headers, but c++ doesn't see swift anymore. I'd greatly appreciate any suggestions.
Topic:
Programming Languages
SubTopic:
Swift
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 filed the following issue on swiftlang/swift on GitHub (Aug 8th), and a followup the swift.org forums, but not getting any replies. As we near the release of Swift 6.2, I want to know if what I'm seeing below is expected, or if it's another case where the compiler needs a fix.
protocol P1: Equatable { }
struct S1: P1 { }
// Error: Conformance of 'S1' to protocol 'P1' crosses into main actor-isolated code an can cause data races
struct S1Workaround: @MainActor P1 { } // OK
// Another potential workaround if `Equatable` conformance can be moved to the conforming type.
protocol P2 { }
struct S2: Equatable, P2 { } // OK
There was a prior compiler bug fix which addressed inhereted protocols regarding @MainActor. For Equatable, one still has to use @MainActoreven when the default actor isolation is MainActor.
Also affects Hashable and any other protocol inheriting from Equatable.
hi,
Is it possible to compare two vectors and get a boolean answer?
example :
uint642_t a;
uint642_t b;
.../...
if(a == b)
.../...
how to do it ?
thank
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
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 get many warnings like this when I build an old project.
I asked AI chatbot which gave me several solutions, the recommended one is:
var hashBag = [String: Int]()
func updateHashBag() async {
var tempHashBag = hashBag // make copy
await withTaskGroup(of: Void.self) { group in
group.addTask {
tempHashBag["key1"] = 1
}
group.addTask {
tempHashBag["key2"] = 2
}
}
hashBag = tempHashBag // copy back?
}
My understanding is that in the task group, the concurrency engine ensures synchronized modifications on the temp copy in multiple tasks. I should not worry about this.
My question is about performance.
What if I want to put a lot of data into the bag? Does the compiler do some kind of magics to optimize low level memory allocations? For example, the temp copy actually is not a real copy, it is a special reference to the original hash bag; it is only grammar glue that I am modifying the copy.
Is there a swift6 manual that will teach me how to code in swift?
I am trying to use initialize a Decimal type using its generic binary integer exactly initializer but it keeps crashing with a fatal error regardless of the value used:
Code to reproduce the issue:
let binaryInteger = -10
let decimal = Decimal(exactly: binaryInteger) // error: Execution was interrupted, reason: EXC_BAD_INSTRUCTION (code=EXC_I386_INVOP, subcode=0x0).
Is it a known bug?
Why Ternary operator in not called a binary Operator or ternary Operands ?
question ? answer1 : answer2
When it takes 2 operators ?
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.
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 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
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
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.
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.
I'm using Network Framework to transfer files between 2 devices. The "secondary" device sends file requests to the "primary" device, and the primary sends the files back.
When the primary gets the request, it responds like this:
do {
let data = try Data(contentsOf: filePath)
let priSecDataFilePacket = PriSecDataFilePacket(fileName: filename, dataBlob: data)
let jsonData = try JSONEncoder().encode(priSecDataFilePacket)
let message = NWProtocolFramer.Message(priSecMessageType: PriSecMessageType.priToSecDataFile)
let context = NWConnection.ContentContext(identifier: "TransferUtility", metadata: [message])
connection.send(content: encodedJsonToSend, contentContext: context, isComplete: true, completion: .idempotent)
} catch {
print("\(error)")
}
It works great, even for hundreds of file requests. The problem arises if some files being requested are extremely large, like 600MB. You can see the memory speedometer on the primary quickly ramp up to the yellow zone, at which point iOS kills the app for high memory use, and you see the Jetsam log.
I changed the code to skip JSON encoding the binary file as a test, and that helped a bit, but it still goes too high; the real offender is the step where it loads the 600MB file into the data var:
let data = try Data(contentsOf: filePath)
If I remark out everything else and just leave that one line, I can still see the memory use spike.
As a fix, I'm rewriting this so the secondary requests the file in 5MB chunks by telling the primary a byte range such as "0-5242880" or "5242881-10485760", and then reassembling the chunks on the secondary once they all come in. So far this seems promising, but it's a fair amount of work.
My question: Does Network Framework have a built-in way to stream those bytes straight from disk as it sends them? So that I could send all the data in one single request without having to load the bytes into memory?
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?
I have a macro that converts expression into a string literal, e.g.:
#toString(variable) -> "variable"
#toString(TypeName) -> "TypeName"
#toString(\TypeName.property) -> "property"
In Xcode 16.3 #toString(TypeName) stopped to work, compilation throws 'Expected member name or initializer call after type name' error.
Everything works fine in Xcode 16.2. I tried to compare build settings between 16.2 and 16.3 but haven't noticed differences that may cause this new error.
The following works in both Xcode versions:
#toString(variable) -> "variable"
#toString(\TypeName.property) -> "property"
Seems like Xcode tries to compile code that shouldn't be compiled because of macro expansion.
Does anybody know what new has appeared in 16.3 and, perhaps, how to fix the problem?