I have a struct defined in Swift, i want to pass it's instance pointer from swift to C++. When I am trying to directly return Typed Pointer from Swift Function to C++, the function doesn't get expose to C++.
Code which i have tried.
// Defined Structure
public struct MyStruct {
public init (_ pValue : Int) {
uValue = pValue
}
public var uValue : Int
}
var my_struct = MyStruct(20)
// Function which returns Struct Pointer to C++
// When I return typed pointer this function doesn't get exposed to C++
public func PassStructPointer () -> UnsafeMutablePointer<MyStruct> {
withUnsafeMutablePointer(to: &my_struct) { pointer in
return pointer
}
}
But when I pass UnsafeRawMutablePointer instead of type pointer then the function does get expose to C++
var my_struct = MyStruct(20)
// This get expose to C++.
public func PassStructPointer () -> UnsafeMutableRawPointer {
return withUnsafeMutableBytes(of: &my_struct) { pointer in
return pointer.baseAddress!
}
}
Can we not pass typed pointer of the types defined by us?
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I have a use case where I want to return reference from Swift Function just like we can do in C++.
This is How we do it in C++:
int & ReturnIntRef () noexcept
{
static int a = 4;
return a;
}
Do we have equivalent of this in Swift ?
Hello,
I'm doing some test and I dowload the sample from here https://developer.apple.com/documentation/networkextension/local_push_connectivity/receiving_voice_and_text_communications_on_a_local_network
Everything works correctly and the phones are able to exchange messages without problems and the server sends pushes to the devices.
Now I would like to modify the server so that, when it sends the push to the mobile device, it can change the sound or add other information as is possible when using APN.
Now I would like to modify the server so that, when it sends the push to the mobile device, it can change the sound or add other information as is possible when using APN.
Is there any way to send a payload like for APN?
Thank's
Omar
I am trying to use the swift type UnsafeMutablePointer directly in C++. According to the documentation mentioned, swift expose this type to C++. But I am not able to use it .
void
GetPointerFromSwift () {
// Calls a swift function to get a pointer.
swift::UnsafeMutablePointer<swit::Int> x = Interop::GetPointer ()
}
When we pass a input to swift function it is passed as a constant, so does copy gets created or not here?
public func Test (_ pValue : Int) {
print (pValue)
}
let x : Int = 2
Test (x)
We have an in-house CLI tool built entirely in Python to help us with OS-level workflows. It’s been excellent, but we’re encountering some growing pains.
We’ve encountered a case where we’d like to use Apple’s Authorization Plugin, which we can’t directly utilize in Python.
Since I doubt this’ll be the last time we encounter Swift or Obj-C specific tools, I’m starting to wonder if a total rewrite into Swift might be in order.
Alternatives include writing a wrapper in Swift just for the Auth Plugin, exposing an API that we’ll consume in Python.
Since this will only ever be a macOS, tool, I’m starting to feel like going with Python was a dumb idea in the first place.
Would love to know what you guys think.
p.s.
I was advised to post my question on these forums in hopes of being graced by the Apple god Quinn, “The Eskimo”.
I have a use-case where I want to pass the user defined swift structure instantiated in swift and then pass it to a C++ Function as a Input Param. Is there a way to do that?
When i instantiate a structure defined in swift in C++ and then i pass it to swift function as a IN param, it is passed as a constant value to the function. Here the same structure instance is passed or a copy is created?
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I'm looking at performance around large codable nested structures that come in from HTTP/JSON.
We are seeing stalls on the main thread, and after reviewing all the code, the webrequests and parsing are async and background. The post to set the new struct value (80K) is handled on mainthread.
When I looked at the nested structures, they are about 80K.
Reading several articles and posts suggested that observing structs will cause a refresh on any change. And that large structures will take longer as they have to be copied for passing to each observer. And that more observers will slow things down.
So a made a test app to verify these premises.
The app has an timer animating a slider.
A VM with a structure containing a byte array.
Sliders to scale the size of the byte array from 10K to 200K and to scale the number of observers from 1 to 100.
It also measures the actual duration between the timer ticks. My intention is to be able to visual see mainthread stalls and be able to measure them and see the average and max frame delays.
Using this to test I found little difference in performance given different structure sizes or number of observers. I'm not certain if this is expected or if I missing something in creating my test app.
I have also created a variation where the top struct is a an observable class. I see no difference between struct or class.
I'm wondering if this is due to copy-on-mutate causing the struct to actually be passed as reference under the good?
I wonder if other optimizations are minimizing the affect of scaling from 1 to 100 observers.
I appreciate any insights & critiques.
#if CLASS_BASED
class LargeStruct: ObservableObject {
@Published var data: [UInt8]
init(size: Int = 80_000) {
self.data = [UInt8](repeating: 0, count: size)
}
func regenerate(size: Int) {
self.data = [UInt8](repeating: UInt8.random(in: 0...255), count: size)
}
var hashValue: String {
let hash = SHA256.hash(data: Data(data))
return hash.compactMap { String(format: "%02x", $0) }.joined()
}
}
#else
struct LargeStruct {
var data: [UInt8]
init(size: Int = 80_000) {
self.data = [UInt8](repeating: 0, count: size)
}
mutating func regenerate(size: Int) {
self.data = [UInt8](repeating: UInt8.random(in: 0...255), count: size)
}
var hashValue: String {
let hash = SHA256.hash(data: Data(data))
return hash.compactMap { String(format: "%02x", $0) }.joined()
}
}
#endif
class ViewModel: ObservableObject {
@Published var largeStruct = LargeStruct()
}
struct ContentView: View {
@StateObject var vm = ViewModel()
@State private var isRotating = false
@State private var counter = 0.0
@State private var size: Double = 80_000
@State private var observerCount: Double = 10
// Variables to track time intervals
@State private var lastTickTime: Date?
@State private var minInterval: Double = .infinity
@State private var maxInterval: Double = 0
@State private var totalInterval: Double = 0
@State private var tickCount: Int = 0
var body: some View {
VStack {
Model3D(named: "Scene", bundle: realityKitContentBundle)
.padding(.bottom, 50)
// A rotating square to visualize stalling
Rectangle()
.fill(Color.blue)
.frame(width: 50, height: 50)
.rotationEffect(isRotating ? .degrees(360) : .degrees(0))
.animation(.linear(duration: 2).repeatForever(autoreverses: false), value: isRotating)
.onAppear {
isRotating = true
}
Slider(value: $counter, in: 0...100)
.padding()
.onAppear {
Timer.scheduledTimer(withTimeInterval: 0.005, repeats: true) { timer in
let now = Date()
if let lastTime = lastTickTime {
let interval = now.timeIntervalSince(lastTime)
minInterval = min(minInterval, interval)
maxInterval = max(maxInterval, interval)
totalInterval += interval
tickCount += 1
}
lastTickTime = now
counter += 0.2
if counter > 100 {
counter = 0
}
}
}
HStack {
Text(String(format: "Min: %.3f ms", minInterval * 1000))
Text(String(format: "Max: %.3f ms", maxInterval * 1000))
Text(String(format: "Avg: %.3f ms", (totalInterval / Double(tickCount)) * 1000))
}
.padding()
Text("Hash: \(vm.largeStruct.hashValue)")
.padding()
Text("Hello, world!")
Button("Regenerate") {
vm.largeStruct.regenerate(size: Int(size)) // Trigger the regeneration with the selected size
}
Button("Clear Stats") {
minInterval = .infinity
maxInterval = 0
totalInterval = 0
tickCount = 0
lastTickTime = nil
}
.padding(.bottom)
Text("Size: \(Int(size)) bytes")
Slider(value: $size, in: 10_000...200_000, step: 10_000)
.padding()
Text("Number of Observers: \(observerCount)")
Slider(value: $observerCount, in: 1...100, step: 5)
.padding()
HStack {
ForEach(0..<Int(observerCount), id: \.self) { index in
Text("Observer \(index + 1): \(vm.largeStruct.data[index])")
.padding(5)
}
}
}
.padding()
}
}
Hello,
I am using the withUnsafePointer API in Swift and have a question regarding the validity of the pointer returned by this API. Specifically, I want to understand if the pointer remains valid if the CPU performs a context switch due to its time-slicing mechanism while the closure is executing.
Is the pointer returned by withUnsafePointer guaranteed to be valid throughout the entire execution of the closure, even if a CPU context switch occurs as part of time slicing?
The following behavior seems like a bug in the swift compiler that ships with Xcode 16 beta 6.
Add the following code snippet to a new iOS app project using Xcode 16 beta 6 and observe the error an warning called out in the comments within the itemProvider() method:
import WebKit
extension WKWebView {
func allowInspectionForDebugBuilds() {
// commenting out the following line makes it so that the completion closure argument of the trailing closure
// passed to NSItemProvider.registerDataRepresentation(forTypeIdentifier:visibility:loadHandler:) is no longer
// isolated to the main actor, thus resolving the build issues. It is unexpected that the presence or absence of
// the following line would have this kind of impact.
isInspectable = true
}
}
class Foo {
func itemProvider() -> NSItemProvider? {
let itemProvider = NSItemProvider()
itemProvider.registerDataRepresentation(forTypeIdentifier: "", visibility: .all) { completion in
Task.detached {
guard let url = URL(string: "") else {
completion(nil, NSError()) // error: Expression is 'async' but is not marked with 'await'
return
}
let task = URLSession.shared.dataTask(with: url) { data, _, error in
completion(data, error) // warning: Call to main actor-isolated parameter 'completion' in a synchronous nonisolated context; this is an error in the Swift 6 language mode
}
task.resume()
}
return Progress()
}
return itemProvider
}
}
Now, comment out the line isInspectable = true and observe that the error and warning disappear.
Also filed as FB14783405 and https://github.com/swiftlang/swift/issues/76171
Hoping to see this fixed before Xcode 16 stable.
I have a usecase, where I have Data instance as Data is Value type copy will be created on assignment. I want to prevent copying for which I was using this Initializer of Data. Will it prevent copying?.
Hi, I was trying to understand how swift manages it memory just wanted to verify my understanding on it.
For Value Types i.e. Struct ARC (Automatic Reference Counting) is not there, Memory is Managed/Confined on the basis of scope of that Variable. And For Struct whenver we do assignment a Copy is been created.
For Classes, Swift Manages Memroy with the help of ARC i.e. whenever I create a instance of class its reference count get increased and when we assign same instance to new variable then it also result in increment of Reference Count. The Memory will get deallocated when all the variables pointing to that object are no longer in use.
So I have this child class with a function that creates a perdetermined array of other classes.
class DirectGame : GameParent {
static func GetAllChallenges() -> Array<ChallengeParent>{
return [LockdownChallenge(game: self)]
}
}
These other classes take in a GameParent class in the initalizer like so:
class LockdownChallenge {
var game : GameParent
init(game: GameParent) {
self.game = game
}
}
However this line
return [LockdownChallenge(game: self)]
is throwing the error
"Cannot convert value of type 'DirectGame.Type' to expected argument type 'GameParent'"
How do I pass in a reference to DirectGame into the initalizer of ChallengeParent?
I am using withUnsafeMutablePointer to get raw pointer from Data. Once I get a Pointer I follow these steps:
I create a Wrapper using that Pointer.
After that I increase it ARC and pass it as a opaque to C++
When I was on First Step if my thread get suspended and after some time if it resumes then is there a possibility that the Memory will get freed due to ARC.
Adding basic Code Flow depicting what i am doing.
public class DataHolder {
public init () {}
public var data_wrapper : Data?
}
func InternalReceiveHandler (_ pContent : Data?) -> Void {
var holder : DataHolder = DataHolder.init ()
withUnsafeMutablePointer (to : &pContent) { data_pointer in
holder.data_wrapper = Data.init (noBytesCopy : data_pointer, count : no_of_bytes, deallocator : .none)
return Unmanaged.passRetained (holder).toOpaque ()
}
}
Is there a possibility that when I am creating the wrapper my thread get suspended and when it get resumed the Memory the pointer was pointing can be freed by ARC.
I'm working on a Payment SDK integrating Storekit2 for Unity games. The workflow is as follows:
build the swift project that exposes objective c interface to static libraries, then archive them into xcframework
embed the xcframework into native unity plugin where we call objective-c functions from C#
export the unity project to Xcode project
build the game Xcode project
When deployment target of swift project is set to iOS15
No matter what iOS version target is set in the game Xcode project, I got build error:
Undefined symbol: __swift_FORCE_LOAD_$_swiftCompatibility56
When deployment target of swift project is set to iOS16
And set the deployment target of game project to iOS15 (I need to let the payment sdk to work on iOS15 as Storekit2 and swift concurrency shipped with iOS15).
I can build the game Xcode project, and it works on iOS16+ device.
But when I run on iOS15 device, I got runtime error:
2024-08-26 18:17:29.289078+0900 ***[1404:95780] Error loading /var/containers/Bundle/Application/123/***/Frameworks/UnityFramework.framework/UnityFramework: dlopen(/var/containers/Bundle/Application/123/***/Frameworks/UnityFramework.framework/UnityFramework, 0x0109): Symbol not found: (_objc_claimAutoreleasedReturnValue)
Referenced from: '/private/var/containers/Bundle/Application/123/***/Frameworks/UnityFramework.framework/UnityFramework'
Expected in: '/usr/lib/libobjc.A.dylib'
2024-08-26 18:17:29.418604+0900 ***[1404:95780] Error loading /var/containers/Bundle/Application/123/***/Frameworks/UnityFramework.framework/UnityFramework: dlopen(/var/containers/Bundle/Application/123/***/Frameworks/UnityFramework.framework/UnityFramework, 0x0109): Symbol not found: (_objc_claimAutoreleasedReturnValue)
Referenced from: '/private/var/containers/Bundle/Application/123/***/Frameworks/UnityFramework.framework/UnityFramework'
Expected in: '/usr/lib/libobjc.A.dylib'
If I chose not to build framework into static libraries but dynamic ones, I can avoid this problem but Unity cannot handle dynamic libraries well when exporting to Xcode project so I have no choice here but to stick to static ones.
minimum reproduction
I made a minimum reproduction project to exclude the process of unity.
a fresh new empty objective-c app project
embed the xcframework built with target iOS15
call a function in the framework in applicationDidFinishLaunch
set the deployment target of main target of the app project to iOS15.
build the project
I still get
Undefined symbol: __swift_FORCE_LOAD_$_swiftCompatibility56
versions
Xcode version 15.4
Test iOS device version 15.8
Do you have to compile your apps with Swift6 enabled to ship a production app when iOS18 is released?
Hi,
How can I improve the CPU usage of my auto scrolling text (horizontal)? Currently I use very short timer
Thank you
Code: https://codeshare.io/Q8A1JJ
I am developing an iPhone app related to finance and currently I am using isCaptured value to prevent screen recording by checking the isCaptured value and if it is true then I blur the video recording.
It was working fine while using UIScreen.main.isCaptured till iOS 17 . But for iOS 18 it became deprecated and it is not working any more. Below is the obj-c code block.
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:
(NSDictionary *)launchOptions
{
if (@available(iOS 11.0, *)) {
BOOL isCaptured = [[UIScreen mainScreen] isCaptured];
if(isCaptured){
// Do the action for hiding the screen recording
}
} else{
// Fallback on earlier versions
}
return YES;
}
The replacement sceneCaptureState is working only for a scene-based app which uses UISceneDelegate lifecycle but it's not working for the old structure so now i have that problem, my iPhone app is very big and does not support scenes at all since we are following UIAppDelegate life cycle for years, what shall I do to prevent screen recording from iOS 18 onwards ?
Note: My iPhone app does not support any scene configuration
Please help me in this.
Regards,
Carol