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
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I have a class object created dynamically using Runtime, and I want to release some manually allocated memory resources when this object is deallocated. To achieve this, I added a custom implementation of the dealloc method using the following code:
SEL aSel = NSSelectorFromString(@"dealloc");
class_addMethod(kvoClass, aSel, (IMP)custom_dealloc, method_getTypeEncoding(class_getInstanceMethod(kvoClass, aSel)));
However, I encountered some issues. If I don't call the superclass's dealloc method in the cus_dealloc function, the superclass's dealloc implementation will not be executed. On the other hand, if I explicitly call the superclass's dealloc method, the program crashes.
Here is the implementation of the cus_dealloc function:
void custom_dealloc(id self, SEL _cmd) {
// Release other memory

Class superClass = class_getSuperclass(object_getClass(self));
void (*originIMP)(struct objc_super *, SEL, ...) = (void *)objc_msgSendSuper;
struct objc_super *objcSuper = &(struct objc_super){self, superClass};
originIMP(objcSuper, _cmd);
}
demo
Hello, I am a software engineer student and I have recently been getting problems on my Mac regarding the C/C++ libraries. I have used my macbook for uni work for months, but around 3 or 4 months ago my macbook could not compile my work since it couldnt find the basic libraries I was using. For example, iostream. I have been using VSCode, and what it exactly says is "cannot open source file "iostream". Please run the 'Select IntelliSense Configuration...' command to locate your system headers." I have tried researching, changing the include path, even using chatgpt, and nothing. Is anyone having this same problem, or is able to help me? If any other information is needed, please let me know!
Topic:
Programming Languages
SubTopic:
General
func oneStepForward(_ input: Int) -> Int {
return input + 1
}
func oneStepBackward(_ input: Int) -> Int {
return input - 1
}
func chooseStepFunction(backward: Bool) -> (Int) -> Int {
return backward ? oneStepBackward : oneStepForward
//Error. type of expression is ambiguous without a type annotation
}
Why am I getting this error ?
If I change this function to the following it works and will compile.
func chooseStepFunction(backward: Bool) -> (Int) -> Int {
if backward {
return oneStepBackward
} else {
return oneStepForward
}
}
// Why am I getting the error in the previous version while it works in the second version ?
Thx in advance.
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
According to the doc:
The value returned is the same as the value returned in the kEventParamKeyCode when using Carbon Events.
So where can I find kEventParamKeyCode?
I have a VPN application published in the app store. Used Ikev2 for this personal VPN. There are two in-app purchases. One is 'Monthly' and another is 'Yearly' with 3 days free trial. We have seen something strange for the yearly subscriptions which has free trail, the cancellation reason through the billing issue is too high like 70-80% due to billing retry state. Some other apps which have billing issues under 10% always. We have done some research and found that if the user doesn't cancel and Apple is unable to charge then it goes to a billing retry state.
If users don't like the app, they could cancel their subscription/free trail easily but they are not doing this and why Apple unable to charge the bill after the trial ends. Am i missing something in the developer end?
I found a similar problem here https://developer.apple.com/forums/thread/764777 and I could solve my problem by wrapping the call to requestAutomaticPassPresentationSuppression in a call to DispatchQueue.global().async.
But my question is if this is really how things should work. Even with strict concurrency warnings in Swift 6 I don't get any warnings. Just a runtime crash.
How are we supposed to find these problems? Couldn't the compiler assist with a warning/error.
Why does the compiler make the assumptions it does about the method that is declared like this:
@available(iOS 9.0, *)
open class func requestAutomaticPassPresentationSuppression(responseHandler: @escaping (PKAutomaticPassPresentationSuppressionResult) -> Void) -> PKSuppressionRequestToken
Now that we have migrated to Swift 6 our code base contains a bunch of unknown places where it will crash as above.
I’m creating an app using SwiftUI, and I would like to incorporate a small Java codebase that I created for the Android version of the app. Is there a way to package the Java code to work on iOS and macOS
Topic:
Programming Languages
SubTopic:
General
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 enabled runtime concurrency warnings to check for future problems concerning concurrency: Build Setting / Other Swift Flags:
-Xfrontend -warn-concurrency -Xfrontend -enable-actor-data-race-checks
When trying to call the async form of PHPhotoLibrary.shared().performChanges{} I get the following runtime warning: warning: data race detected: @MainActor function at ... was not called on the main thread in the line containing performChanges.
My sample code inside a default Xcode multi platform app template is as follows:
import SwiftUI
import Photos
@MainActor
class FotoChanger{
func addFotos() async throws{
await PHPhotoLibrary.requestAuthorization(for: .addOnly)
try! await PHPhotoLibrary.shared().performChanges{
let data = NSDataAsset(name: "Swift")!.data
let creationRequest = PHAssetCreationRequest.forAsset()
creationRequest.addResource(with: .photo, data: data, options: PHAssetResourceCreationOptions())
}
}
}
struct ContentView: View {
var body: some View {
ProgressView()
.task{
try! await FotoChanger().addFotos()
}
}
}
You would have to have a Swift data asset inside the asset catalog to run the above code, but the error can even be recreated if the data is invalid.
But what am I doing wrong? I have not found a way to run perform changes, the block or whatever causes the error on the main thread.
PS: This is only test code to show the problem, don't mind the forced unwraps.
For my app I've created a Dictionary that I want to persist using AppStorage
In order to be able to do this, I added RawRepresentable conformance for my specific type of Dictionary. (see code below)
typealias ScriptPickers = [Language: Bool]
extension ScriptPickers: @retroactive RawRepresentable where Key == Language, Value == Bool {
public init?(rawValue: String) {
guard let data = rawValue.data(using: .utf8),
let result = try? JSONDecoder().decode(ScriptPickers.self, from: data)
else {
return nil
}
self = result
}
public var rawValue: String {
guard let data = try? JSONEncoder().encode(self), // data is Data type
let result = String(data: data, encoding: .utf8) // coerce NSData to String
else {
return "{}" // empty Dictionary represented as String
}
return result
}
}
public enum Language: String, Codable, {
case en = "en"
case fr = "fr"
case ja = "ja"
case ko = "ko"
case hr = "hr"
case de = "de"
}
This all works fine in my app, however trying to run any tests, the build fails with the following:
Conflicting conformance of 'Dictionary<Key, Value>' to protocol 'RawRepresentable'; there cannot be more than one conformance, even with different conditional bounds
But then when I comment out my RawRepresentable implementation, I get the following error when attempting to run tests:
Value of type 'ScriptPickers' (aka 'Dictionary<Language, Bool>') has no member 'rawValue'
I hope Joseph Heller is out there somewhere chuckling at my predicament
any/all ideas greatly appreciated
Using the DebugDescription macro to display an optional value produces a “String interpolation produces a debug description for an optional value” build warning.
For example:
@DebugDescription
struct MyType: CustomDebugStringConvertible {
let optionalValue: String?
public var debugDescription: String {
"Value: \(optionalValue)"
}
}
The DebugDescription macro does not allow (it is an error)
"Value: \(String(describing: optionalValue))"
or
"Value: \(optionalValue ?? "nil")"
because “Only references to stored properties are allowed.”
Is there a way to reconcile these?
I have a build log full of these warnings, obscuring real issues.
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 ?
Last night my iPhone game crashed while running in debug mode on my iPhone. I just plugged it into my Mac, and was able to find the ips file. The stack trace shows the function in my app where it crashed, and then a couple of frames in libswiftCore.dylib before an assertion failure.
My question is - I've got absolutely no idea what the assertion failure actually was, all I have is...
0 libswiftCore.dylib 0x1921412a0 closure #1 in closure #1 in closure #1 in _assertionFailure(_:_:file:line:flags:) + 228
1 libswiftCore.dylib 0x192141178 closure #1 in closure #1 in _assertionFailure(_:_:file:line:flags:) + 327
2 libswiftCore.dylib 0x192140b4c _assertionFailure(_:_:file:line:flags:) + 183
3 MyGame.debug.dylib 0x104e52818 SentryBrain.takeTurn(actor:) + 1240
...
How do I figure out what the assertion failure was that triggered the crash? How do I figure out what line of code in takeTurn(...) triggered the failing assertion failure?
Is this possible while inserting a String into Set
Crashed: com.apple.root.user-initiated-qos.cooperative
0 libswiftCore.dylib 0xf4c0 _assertionFailure(_:_:flags:) + 136
1 libswiftCore.dylib 0x17f484 ELEMENT_TYPE_OF_SET_VIOLATES_HASHABLE_REQUIREMENTS(_:) + 3792
2 MyEatApp 0x44f6e8 specialized _NativeSet.insertNew(_:at:isUnique:) + 4333926120 (<compiler-generated>:4333926120)
3 MyEatApp 0x44eaec specialized Set._Variant.insert(_:) + 4333923052 (<compiler-generated>:4333923052)
4 MyEatApp 0x479f7c HomeViewModel.hanldeAnnouncementCard(from:) + 293 (HomeViewModel+PersonalizedOffer.swift:293)
5 libswift_Concurrency.dylib 0x5c134 swift::runJobInEstablishedExecutorContext(swift::Job*) + 292
6 libswift_Concurrency.dylib 0x5d5c8 swift_job_runImpl(swift::Job*, swift::SerialExecutorRef) + 156
7 libdispatch.dylib 0x13db0 _dispatch_root_queue_drain + 364
8 libdispatch.dylib 0x1454c _dispatch_worker_thread2 + 156
9 libsystem_pthread.dylib 0x9d0 _pthread_wqthread + 232
10 libsystem_pthread.dylib 0xaac start_wqthread + 8
Hello,
I am developing a private internal Flutter app for our customer, which will not be published on the Apple Store. One of the key features of this app is to collect RF strength metrics to share user experience with the network.
For Android, we successfully implemented the required functionality and are able to collect the following metrics:
Signal strength level (0-4)
Signal strength in dBm
RSSI
RSRQ
Cell ID
Location Area Code
Carrier name
Mobile country code
Mobile network code
Radio access technology
Connection status
Duplex mode
However, for iOS, we are facing challenges with CoreTelephony, which is not returning the necessary data. We are aware that CoreTelephony is deprecated and are looking for alternatives.
We noticed that a lot of the information we need is available via FTMInternal-4. Is there a way to access this data for a private app? Are there any other recommended approaches or frameworks that can be used to gather cellular network information on iOS for an app that won't be distributed via the Apple Store?
my swift code
import Foundation
import CoreTelephony
class RfSignalStrengthImpl: RfSignalStrengthApi {
func getCellularSignalStrength(completion: @escaping (Result<CellularSignalStrength, Error>) -> Void) {
let networkInfo = CTTelephonyNetworkInfo()
guard let carrier = networkInfo.serviceSubscriberCellularProviders?.values.first else {
completion(.failure(NSError(domain: "com.xxxx.yyyy", code: 0, userInfo: [NSLocalizedDescriptionKey: "Carrier not found"])))
return
}
let carrierName = carrier.carrierName ?? "Unknown"
let mobileCountryCode = carrier.mobileCountryCode ?? "Unknown"
let mobileNetworkCode = carrier.mobileNetworkCode ?? "Unknown"
let radioAccessTechnology = networkInfo.serviceCurrentRadioAccessTechnology?.values.first ?? "Unknown"
var connectionStatus = "Unknown"
...
...
}
Thank you for your assistance.
I have a class that I want to custom encode into JSON:
class Declination: Decodable, Encodable {
var asString: String
var asDouble: Double
init(_ asString: String) {
self.asString = asString
self.asDouble = raToDouble(asString)
}
required init(from decoder: Decoder) throws {
let value = try decoder.singleValueContainer()
self.asString = try value.decode(String.self)
self.asDouble = declinationToDouble(asString)
}
}
As you can see, I calculate the double form of the declination when I decode a JSON file containing the data. What I want to do now is ENCODE the class back out as a single string.
Currently the standard JSON encode in Swift produces the following:
"declination":{"asDouble":18.26388888888889,"asString":"+18:15:50.00"}
what I want to produce is:
declination:"+18:15:50.00"
How can I easily do that? I've read up about custom encoders and such, and I get confused about the containers and what keys are being used. I think there might be a simple answer where I could just code:
extension Coordinate: Encodable {
func encode(to encoder: Encoder) throws {
return encoder.encode(self.asString)
}
}
But experienced Swift developers will immediately see that won't work. Should I do JSONSerialization instead? Can I just write a toString() extension and have JSON pick that up?
Any help would be appreciated.
Thanks,
Robert
Topic:
Programming Languages
SubTopic:
Swift
As a fun project, I'm wanting to model an electronic circuit.
Components inherit from a superclass (ElectronicComponent). Each subclass (e.g. Resistor) has certain methods to return properties (e.g. resistance), but may vary by the number of outlets (leads) they have, and what they are named.
Each outlet connects to a Junction.
In my code to assemble a circuit, while I'm able to manually hook up the outlets to the junctions, I'd like to be able to use code similar to the following…
class Lead: Hashable // implementation omitted
{
let id = UUID()
unowned let component: ElectronicComponent
weak var connection: Junction?
init(component: ElectronicComponent, to connection: Junction? = nil)
{
self.component = component
self.connection = connection
}
}
@dynamicMemberLookup
class ElectronicComponent
{
let id = UUID()
var connections: Set<Lead> = []
let label: String?
init(label: String)
{
self.label = label
}
subscript<T>(dynamicMember keyPath: KeyPath<ElectronicComponent, T>) -> T
{
self[keyPath: keyPath]
}
func connect(lead: KeyPath<ElectronicComponent, Lead>, to junction: Junction)
{
let lead = self[keyPath: lead]
lead.connection = junction
connections.insert(lead)
}
}
class Resistor: ElectronicComponent
{
var input, output: Lead?
let resistance: Measurement<UnitElectricResistance>
init(_ label: String, resistance: Measurement<UnitElectricResistance>)
{
self.resistance = resistance
super.init(label: label)
}
}
let resistorA = Resistor("R1", resistance: .init(value: 100, unit: .ohms))
let junctionA = Junction(name: "A")
resistorA.connect(lead: \.outlet2, to: junctionA)
While I'm able to do this by implementing @dynamicMemberLookup in each subclass, I'd like to be able to do this in the superclass to save repeating the code.
subscript<T>(dynamicMember keyPath: KeyPath<ElectronicComponent, T>) -> T
{
self[keyPath: keyPath]
}
Unfortunately, the compiler is not allowing me to do this as the superclass doesn't know about the subclass properties, and at the call site, the subclass isn't seen as ElectronicComponent.
I've been doing trial and error with protocol conformance and other things, but hitting walls each time.
One possibility is replacing the set of outlets with a dictionary, and using Strings instead of key paths, but would prefer not to.
Another thing I haven't tried is creating and adopting a protocol with the method implemented in there. Another considered approach is using macros in the subclasses, but I'd like to see if there is a possibility of achieving the goal using my current approach, for learning as much as anything.
I have configured DateFormatter in the following way:
let df = DateFormatter()
df.dateFormat = "yyyy-MM-dd'T'HH:mm:ss'Z'"
df.locale = .init(identifier: "en")
df.timeZone = .init(secondsFromGMT: 0)
in some user devices instead of ISO8601 style it returns date like 09/25/2024 12:00:34
Tried to change date format from settings, changed calendar and I think that checked everything that can cause the problem, but nothing helped to reproduce this issue, but actually this issue exists and consumers complain about not working date picker.
Is there any information what can cause such problem? May be there is some bug in iOS itself?