Hi all,
Background:
I am working as a library developer and would like to enable Swift C++ interoperability in our library. Our library supports both CocoaPods and SPM.
Question:
I would like to know whether it is possible to avoid breaking changes bring to the library users after enabling Swift C++ interoperability.
In my experiment, all apps and packages depend on the library needs to enable interoperability in Xcode or package manage tools, otherwise the source code cannot be complied.
I am wondering is there any ways to bypass this? For example, is there a way to only enable Swift C++ interoperability only in our libraries?
Dive into the world of programming languages used for app development.
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macOS: Sequoia
Xcode: 16.1
I am working on a macOS app and it has a widget feature.
When I use Swift 6 (Build Settings > Swift Language Version) in IntentExtension, the intent configuration won't show up in macOS Sequoia.
If I downgrade to Swift 5, it works without any other changes.
Is it a bug or am I missing something? How can I use Swift 6 with IntentExtension.
I'll describe my crash with an example, looking for some insights into the reason why this is happening.
@objc public protocol LauncherContainer {
var launcher: Launcher { get }
}
@objc public protocol Launcher: UIViewControllerTransitioningDelegate {
func initiateLaunch(url: URL, launchingHotInstance: Bool)
}
@objc final class LauncherContainer: NSObject, LauncherContainer, TabsContentCellTapHandler {
...
init(
...
) {
...
super.init()
}
...
//
// ContentCellTapHandler
//
public func tabContentCellItemDidTap(
tabId: String
) {
...
launcher.initiateNewTabNavigation(
tabId: tabId // Crash happens here
)
}
public class Launcher: NSObject, Launcher, FooterPillTapHandler {
public func initiateNewTabNavigation(tabId: String) {
...
}
}
public protocol TabsContentCellTapHandler: NSObject {
func tabContentCellItemDidTap(
tabId: String,
}
I'll describe my crash with an example, looking for some insights into the reason why this is happening.
@objc public protocol LauncherContainer {
var launcher: Launcher { get }
}
@objc public protocol Launcher: UIViewControllerTransitioningDelegate {
func initiateLaunch(url: URL, launchingHotInstance: Bool)
}
@objc final class LauncherContainer: NSObject, LauncherContainer, TabsContentCellTapHandler {
...
init(
...
) {
...
super.init()
}
...
//
// ContentCellTapHandler
//
public func tabContentCellItemDidTap(
tabId: String
) {
...
launcher.initiateNewTabNavigation(
tabId: tabId // Crash happens here
)
}
public class Launcher: NSObject, Launcher, FooterPillTapHandler {
public func initiateNewTabNavigation(tabId: String) {
...
}
}
public protocol TabsContentCellTapHandler: NSObject {
func tabContentCellItemDidTap(
tabId: String,
}
Crash stack last 2 lines are- libswiftCore.dylib swift_unknownObjectRetain libswiftCore.dylib String._bridgeToObjectiveCImpl()
String._bridgeToObjectiveCImpl() gets called when the caller and implementation is in Swift file
I believe due to @objc class LauncherContainer there'd be bridging header generated. Does that mean tabId passed to tabContentCellItemDidTap is a String but the one passed to initiateNewTabNavigation is NSString?
TabId is UUID().uuidString if that helps. Wondering if UUID().uuidString has something to do with this.
Thanks a ton for helping. Please find attached screenshot of the stack trace.
In my project, i have a Swift class with a class level property of type string. Like this :
class TWSwiftString {
var pString:String!
init(_ pString: String) {
self.pString = pString
}
}
I am creating intance of this class and then creating a opaque pointer to this intance. Like this :
let str = TWSwiftString("World")
// Increasing RC by 1
strptr = Unmanaged.passRetained(str).toOpaque()
Now using this opaque pointer i want to modify the value of pString by directly operating on memory. Like this:
withUnsafeMutablePointer(to: &strptr.pString) { strPointer in
strPointer.pointee = "World"
}
Although i am able to modify pString like this and print. Lets assume i have a approach to make sure memory remains valid when it is operated on and freeing of memory is also handled somehow .
Will this approach work if i have 100s of intance of this string which are being operated in this manner ? What if the size of new value is greater than existing string value ? For this i am thinking of chunk of memory initially and then keep on increasing size of it as bigger string then this chunk comes. Does this approach seems feasible ? Any other problems i can encounter by using this approach ?
Chatgpt gave this answer :
To directly update the memory of a Swift class’s property, particularly to alter a String property, is generally discouraged due to Swift's memory safety model. However, if we want to access and modify a class property directly, the best practice is to use a property accessor, as manually altering memory could lead to undefined behavior or even crashes. Why Direct Memory Manipulation Is Risky When you attempt to manipulate memory directly, especially with Swift’s memory model, you might alter not only the value but also the memory layout of Swift’s String type, which could break things internally. The Swift compiler may store String differently based on the internal structure, so even if we manage to locate the correct memory address, directly modifying it is unreliable.
do you have any opinion around chatgpt resoponse ?
So I found out clang can do multiarch compiles (-arch arm64 -arch x86_64). But Apple seems to have left precompiled header support out. So I built the pch separately for each arch. That all works.
The next problem is that one needs to specify -include-pch foo.x64.pch and -include-pch foo.arm64.pch on the command line. This doesn't work on the compile line, since it tries to prepend arm64 AST to a x64 .o file, and vice versa.
So there is -Xarch_arm64 and -Xarch_x86_64 . But that option is limited to one argument. But "-include-pch foo.x64.pch" is two arguments.
More details of failed attempts here:
https://github.com/llvm/llvm-project/issues/114626
And no splitting out the builds isn't the same, because then -valid_arch I don't think skips the other build. This are all libraries being built by Make, and then the universal app built using an Xcode project from the libraries.
When Xcode is connected to the mobile phone for debugging, the app that contains the logic of executing machine code runs normally, but if Xcode is disconnected and the app is run alone, it will crash.
First use the xcode-run execution function to start the app
The machine code logic executes normally
Disconnect the phone from xcode
Start the app
5.Crash
Here is the test code:https://gitee.com/FanChiang_admin/demo.git
I am using swiftui lately in my iOS mobile app, The Mobile app already has a pipeline that detect any experimental features and throw an error
I am using swift 5 and as you all know SwiftUI is using some of OpaqueTypeErasure utility types like "some"
I heard that in swift 6 the OpaqueTypeErasure is not experimental anymore
But upgrading the app swift version will be a very long process
Also changing the pipeline will be a very long and tiring process
So i want to know if there is a way to remove OpaqueTypeErasure from SwiftUI and what is the alternatives for bypassing the error that being thrown from the pipeline
I have a relatively unique project layered with file types (top to bottom) SwiftUI, Swift, Objective C, and C. The purpose of this layering is that I have a C language firmware application framework for development of firmware on custom electronic boards.
Specifically, I use the standard C preprocessor in specific ways to make data driven structures, not code. There are header files shared between the firmware project and the Xcode iPhone app to set things like the BLE protocol and communication command/reply protocols, etc. The app is forced to adhere to that defined by the firmware, rather than rely a design to get it right.
The Objective C code is mainly to utilize the Bluetooth stack provided by iOS. I specifically use this approach to allow C files to be compiled. Normally, everything has worked perfectly, but a serious and obtuse problem just surfaced a couple days ago.
My important project was created long ago. More recently, I started a new project using most of the same technology, but its project is newer. Ironically, it continues to work perfectly, but ironically the older project stopped working. (Talking about the Xcode iOS side.)
Essentially, the Objective C handling of the C preprocessor is not fully adhering to the standard C preprocessing in one project. It's very confusing because there is no code change. It seems Xcode was updated, but looks like the project was not updated, accordingly? I'm guessing there is some setting that forces Objective C to adhere to the standard C preprocessor rules.
I did see a gnu compiler version that did not get updated compared to the newer project, but updating that in the Build Settings did not fix the problem.
The error is in the title:
Token is not a valid binary operator in a preprocessor subexpression.
The offending macro appears in a header file, included in several implementation files. Compiling a single implementation files isolates the issue somewhat. An implementation with no Objective C objects compiles just fine. If there are Objective C objects then I get the errors. Both cases include the same header.
It seems like the Objective C compiler, being invoked, uses a different C preprocessor parser, rather than the standard. I guess I should mention the bridging header file where these headers exist, as well. The offending header with the problem macro appears as an error in the bridging header if a full build is initiated.
Is there an option somewhere, that forces the Objective C compiler to honor the standard C processor? Note, one project seems to.
#define BLE_SERVICE_BLANK( enumTag, uuid, serviceType )
#define BLE_CHARACTERISTIC_BLANK( enumTag, uuid, properties, readPerm, writePerm, value)
#define BLE_SERVICE_ENUM_COUNTER( enumTag, uuid, serviceType) +1
#define BLE_CHARACTERISTIC_ENUM_COUNTER( enumTag, uuid, properties, readPerm, writePerm, value) +1
#if 0 BLE_SERVICE_LIST(BLE_SERVICE_ENUM_COUNTER, BLE_CHARACTERISTIC_BLANK) > 0
#define USING_BLE_SERVICE
...
#if 0 BLE_SERVICE_LIST(BLE_SERVICE_BLANK, BLE_CHARACTERISTIC_ENUM_COUNTER) > 0
#define USING_BLE_CHARACTERISTIC
...
token is not a valid binary operator in a preprocessor subexpression
refers to the comparison. BLE_SERVICE_LIST() does a +1 for each item in the list. There is no further expansion. One counts services. The other counts characteristics. The errors are associated with the comparisons.
I used struct in the swift file, but once I use xcode build. It will automatically change to enum, causing build failure. But it turns out that this file can be used to build. Since upgrading to XCode16.1, it's not working anymore. I don't know where to set it up. Do not optimize or modify my code.
Error message: 'Padding' cannot be constructed because it has no accessible initializers
My environment is:
macos sequoia 15.1
xcode 16.1(16B40)
File source code:
let π: CGFloat = .pi
let customUserAgent: String = "litewallet-ios"
let swiftUICellPadding = 12.0
let bigButtonCornerRadius = 15.0
enum FoundationSupport {
static let dashboard = "https://support.litewallet.io/"
}
enum APIServer {
static let baseUrl = "https://api-prod.lite-wallet.org/"
}
enum Padding {
subscript(multiplier: Int) -> CGFloat {
return CGFloat(multiplier) * 8.0
}
subscript(multiplier: Double) -> CGFloat {
return CGFloat(multiplier) * 8.0
}
}
enum C {
static let padding = Padding()
enum Sizes {
static let buttonHeight: CGFloat = 48.0
static let sendButtonHeight: CGFloat = 165.0
static let headerHeight: CGFloat = 48.0
static let largeHeaderHeight: CGFloat = 220.0
}
static var defaultTintColor: UIColor = UIView().tintColor
Enum was originally SRTUCT. But the build has been automatically optimized
I would like to see examples of how to do this. Apple states that explicit clang modules don't work with C++ interop. ObjC++ has simple interop with C++. Swift does not. And so I'd like to know how to setup my C++ projects to build them as clang modules.
I have an app whose logic is in C++ and rest of the parts (UI) are in Swift and SwiftUI.
Exceptions can occur in C++ and Swift. I've got the C++ part covered by using the Linux's signal handler mechanism to trap signals which get raised due to exceptions.
But how should I capture exceptions in Swift? When I say exceptions in Swift, I mean, divide by zero, force unwrapping of an optional containing nil, out of index access in an array, etc. Basically, anything that can go wrong, I don't want my app to abruptly crash... I need a chance to finalise my stuff, alert the user, prepare diagnostic reports and terminate. I'm looking for a 'catch-all' exception handler. As an example, let's take Android. In Android, there is the setDefaultUncaughtExceptionHandler method to register for all kinds of exceptions in any thread in Kotlin. I'm looking for something similar in Swift that should work for macOS, iOS & iPadOS, tvOS and watchOS.
I first came across the NSSetUncaughtExceptionHandler method. My understanding is, this only works when I explicitly raise NSExceptions. When I tested it, observed that the exception handler didn't get invoked for either case - divide by zero or invoking raise.
class AppDelegate: NSObject, NSApplicationDelegate {
func applicationDidFinishLaunching(_ aNotification: Notification) {
Log("AppDelegate.applicationDidFinishLaunching(_:)")
// Set the 'catch-all' exception handler for Swift exceptions.
Log("Registering exception handler using NSSetUncaughtExceptionHandler()...")
NSSetUncaughtExceptionHandler { (exception: NSException) in
Log("AppDelegate.NSUncaughtExceptionHandler()")
Log("Exception: \(exception)")
}
Log("Registering exception handler using NSSetUncaughtExceptionHandler() succeeded!")
// For C++, use the Linux's signal mechanism.
ExceptionHandlingCpp.RegisterSignals()
//ExceptionHandlingCpp.TestExceptionHandler()
AppDelegate.TestExceptionHandlerSwift()
}
static func TestExceptionHandlerSwift() {
Log("AppDelegate.TestExceptionHandlerSwift()")
DivisionByZero(0)
}
private static func DivisionByZero(_ divisor: Int) {
Log("AppDelegate.DivisionByZero()")
let num1: Int = 2
Log("Raising Exception...")
//let result: Int = num1/divisor
let exception: NSException = NSException(name: NSExceptionName(rawValue: "arbitrary"), reason: "arbitrary reason", userInfo: nil)
exception.raise()
Log("Returning from DivisionByZero()")
}
}
In the above code, dividing by zero, nor raising a NSException invokes the closure passed to NSSetUncaughtExceptionHandler, evident from the following output logs
AppDelegate.applicationWillFinishLaunching(_:)
AppDelegate.applicationDidFinishLaunching(_:)
Registering exception handler using NSSetUncaughtExceptionHandler()...
Registering exception handler using NSSetUncaughtExceptionHandler() succeeded!
ExceptionHandlingCpp::RegisterSignals()
....
AppDelegate.TestExceptionHandlerSwift()
AppDelegate.DivisionByZero()
Raising Exception...
Currently, I'm reading about ExceptionHandling framework, but this is valid only for macOS.
What is the recommended way to capture runtime issues in Swift?
We are seeing a crash on Big Sur 11.7.10 after switching the build system to use Xcode 15
Excerpt from crash
Time Awake Since Boot: 1700 seconds
System Integrity Protection: enabled
Crashed Thread: 0
Exception Type: EXC_CRASH (SIGABRT)
Exception Codes: 0x0000000000000000, 0x0000000000000000
Exception Note: EXC_CORPSE_NOTIFY
Termination Reason: DYLD, [0x4] Symbol missing
Application Specific Information:
dyld: launch, loading dependent libraries
Dyld Error Message:
Symbol not found: __ZNSt3__17codecvtIDiDu11__mbstate_tE2idE
Referenced from: /Applications/SecureworksTaegis.app/Contents/MacOS/com.secureworks.agent.daemon.app/Contents/MacOS/com.secureworks.agent.daemon
Expected in: /usr/lib/libc++.1.dylib
in /Applications/SecureworksTaegis.app/Contents/MacOS/com.secureworks.agent.daemon.app/Contents/MacOS/com.secureworks.agent.daemon
Build system has the following specs :
ProductName: macOS
ProductVersion: 14.3.1
BuildVersion: 23D60
Xcode 15.2
Build version 15C500b
CMAKE PROPS
set(CMAKE_CXX_STANDARD 20)
set(CMAKE_CXX_EXTENSIONS OFF)
set(CMAKE_OSX_DEPLOYMENT_TARGET 11.0)
I wonder if this is correct behavior. I was surprised to get this result when compiling and running the following C code with Apple clang version 14.0.0 (clang-1400.0.29.102) target arm64-apple-darwin21.6.0 on a M1 Pro 12.7.6 with cc -O2 file.c:
#include <stdio.h>
#include <stdlib.h>
unsigned long long factorial(int n)
{
unsigned long long fac = 1;
while (n > 0)
fac *= n;
return fac;
}
int main()
{
return factorial(1);
}
Compiling with -O2 and running this code gives "Trace/BPT trap".
Checking with LLDB:
$ lldb ./a.out
(lldb) target create "./a.out"
Current executable set to '/Users/engelen/Projects/Euler/a.out' (arm64).
(lldb) run
Process 79580 launched: '/Users/engelen/Projects/Euler/a.out' (arm64)
Process 79580 stopped
* thread #1, queue = 'com.apple.main-thread', stop reason = EXC_BREAKPOINT (code=1, subcode=0x100003fb4)
frame #0: 0x0000000100003fb4 a.out`main at 20.c:9:3 [opt]
6 unsigned long long fac = 1;
7 while (n > 0)
8 fac *= n;
-> 9 return fac;
10 }
11
12 int main()
The loop is non-terminating. But a breakpoint trap is triggered at the return statement. The code should just hang in the loop IMO, not trap, because it never updates variable n (a correct factorial function should decrement n). Never seen this before (not since I started wiring C code in the 80s.)
If I change the update *= into += then there is no trap.
hi
i want create a commande line tool for arm64 et intel x86-64
Xcode 16 macbook pro M3
my setting :
and
but my application compile only for arm64
who can explain to me ?
This is similar to this post https://developer.apple.com/forums/thread/700770 on using objc_copyClassList to obtain the available classes. When iterating the list, I try casting the result to an instance of a protocol and that works fine:
protocol DynamicCounter {
init(controlledByPlayer: Bool, game: Game)
}
class BaseCounter: NSObject, DynamicCounter {
}
static func withAllClasses<R>(
_ body: (UnsafeBufferPointer<AnyClass>) throws -> R
) rethrows -> R {
var count: UInt32 = 0
let classListPtr = objc_copyClassList(&count)
defer {
free(UnsafeMutableRawPointer(classListPtr))
}
let classListBuffer = UnsafeBufferPointer(
start: classListPtr, count: Int(count)
)
return try body(classListBuffer)
}
static func initialize() {
let monoClasses = withAllClasses { $0.compactMap { $0 as? DynamicCounter.Type } }
for cl in monoClasses {
cl.initialize()
}
}
The above code works fine if I use DynamicCounter.Type on the cast but crashes if try casting to BaseCounter.Type instead.
Is there a way to avoid the weird and non Swift classes?
I have a problem with the following code, I am not being notified of changes to the progress property of my Job object, which is @Observable... This is a command-line Mac application (the same code works fine in a SwiftUI application).
I must have missed something?
do {
let job = AsyncJob()
withObservationTracking {
let progress = job.progress
} onChange: {
print("Current progress: \(job.progress)")
}
let _ = try await job.run()
print("Done...")
} catch {
print(error)
}
I Try this without any success:
@main
struct MyApp {
static func main() async throws {
// my code here
}
}
Hi!
I'm trying to implement Swift 6 in my code but can't fix one problem.
Here is my code example which could be run in playground:
import UIKit
import WatchConnectivity
public final class MulticastDelegate<T>: Sendable {
nonisolated(unsafe) private var delegates = [WeakWrapper]()
public init() { }
public var isEmpty: Bool {
return delegates.isEmpty
}
public func addDelegate(_ delegate: T) {
let wrapper = WeakWrapper(value: delegate as AnyObject)
delegates.append(wrapper)
}
public func removeDelegate(_ delegate: T) {
delegates = delegates.filter { $0.value !== delegate as AnyObject }
}
public func invokeDelegates(_ invocation: (T) -> Void) {
for (index, delegate) in delegates.enumerated().reversed() {
if let delegate = delegate.value as? T {
invocation(delegate)
} else {
delegates.remove(at: index)
}
}
}
public func invokeDelegatesCheckingResponse(_ invocation: (T) -> Bool) -> Bool {
var isHandled = false
for delegate in delegates {
if let delegate = delegate.value as? T {
if invocation(delegate) {
isHandled = true
break
}
}
}
return isHandled
}
private final class WeakWrapper: Sendable {
nonisolated(unsafe) weak var value: AnyObject?
init(value: AnyObject) {
self.value = value
}
}
}
@globalActor public actor WatchActor {
public static var shared = WatchActor()
}
@MainActor
@objc public protocol WatchCommunicatorDelegate: NSObjectProtocol {
@objc optional func watchCommunicatorDidRequestDataUpdate(_ controller: WatchCommunicator)
}
@WatchActor
@objc public final class WatchCommunicator: NSObject {
private let multicastDelegate = MulticastDelegate<WatchCommunicatorDelegate>()
}
extension WatchCommunicator: @preconcurrency WCSessionDelegate {
public func session(_ session: WCSession, activationDidCompleteWith activationState: WCSessionActivationState, error: (any Error)?) {
multicastDelegate.invokeDelegates { delegate in
Task { @MainActor in
delegate.watchCommunicatorDidRequestDataUpdate?(self)
}
}
}
public func sessionDidBecomeInactive(_ session: WCSession) {
}
public func sessionDidDeactivate(_ session: WCSession) {
}
}
I want to work with WatchCommunicator in global actor and WatchCommunicatorDelegate should be call in main actor and should have reference to WatchCommunicator.
Help please
Hi,
Considering this method I'd like to test:
public func play(_ soundFileName: String, shouldLoop: Bool) {
Task {
await dataSource.play(soundFileName, shouldLoop: shouldLoop)
}
}
Previously, with XCTest we could use an expectation and wait for it to be fulfilled:
func test()
sut.play("", shouldLoop: false)
wait(for: [mockedAudioPlayerDataSource.invokedPlayExpectation])
XCTAssertEqual(mockedAudioPlayerDataSource.invokedPlayCount, 1)
With Swift Testing, I am unsure what a unit test looks like.
i have macos 15 and xcode 16 swift 6 and want to make apps
to run on macintosh.
i know the syntax of this programming language, but i need
informations like which libraries i have to import for func's
which name i do not know, and parameters i have not found
on websites or the tutorial on swift.
i need procedures like
open window at x,y,width,height
draw rectangle at x,y,width,height,color
draw text at x,y,width,height,color,size
read keyboard-letter,up/dn,shift
read mouse x,y,buttons