This topic area is about the programming languages themselves, not about any specific API or tool. If you have an API question, go to the top level and look for a subtopic for that API. If you have a question about Apple developer tools, start in the Developer Tools & Services topic.
For Swift questions:
If your question is about the SwiftUI framework, start in UI Frameworks > SwiftUI.
If your question is specific to the Swift Playground app, ask over in Developer Tools & Services > Swift Playground
If you’re interested in the Swift open source effort — that includes the evolution of the language, the open source tools and libraries, and Swift on non-Apple platforms — check out Swift Forums
If your question is about the Swift language, that’s on topic for Programming Languages > Swift, but you might have more luck asking it in Swift Forums > Using Swift.
General:
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Swift:
Forums subtopic: Programming Languages > Swift
Forums tags: Swift
Developer > Swift website
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The Swift Programming Language documentation
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Quinn “The Eskimo!” @ Developer Technical Support @ Apple
let myEmail = "eskimo" + "1" + "@" + "apple.com"
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Will Apple continue to support it, or will we wake up one day to find that Swift is the only viable language?It's a serious question. Careers depend on it. I don't accept the "No comment" approach that Apple usually takes. It's cruel.I'm willing to put the time into learning Swift if I have to. I'm not going to do it if I don't. I want to know.Frank
The speaker mentions there is "less risk of creating a retain cycle in when capturing self in a closure within a value type", such as a SwiftUI view struct.
Can you elaborate on when this could actually occur?
Thanks!
similiar to
Error when debugging: Cannot creat… | Apple Developer Forums - https://developer.apple.com/forums/thread/651375
Xcode 12 beta 1 po command in de… | Apple Developer Forums - https://developer.apple.com/forums/thread/651157
which do not resolve this issue that I am encountering
Description of problem
I am seeing an error which prevents using lldb debugger on Swift code/projects. It is seen on any Swift or SwiftUI project that I've tried. This is the error displayed in lldb console when first breakpoint is encountered:
Cannot create Swift scratch context (couldn't create a ClangImporter)(lldb)
Xcode Version 12.3 (12C33)
macOS Big Sur Intel M1
Troubleshooting
I originally thought this was also working on an Intel Mac running Big Sur/Xcode 12.3, but was mistaken. Using my customized shell environment on the following setups, I encounter the same couldn't create a ClangImporter.
M1 Mac mini, main account (an "Admin" account)
same M1 Mac mini, new "dev" account (an "Admin" account)
Intel MBP, main account
They are all using an Intel Homebrew install, and my customized shell environment if that provides a clue?
I captured some lldb debugging info by putting expr types in ~/.lldbinit but the outputs were basically identical (when discounting scratch file paaths and memory addresses) compared to the "working clean" account log (described below)
log enable -f /tmp/lldb-log.txt lldb expr types
works in a "clean" user account
I created a new, uncustomized "Standard" testuser account on the M1 Mac mini, and launched the same system Xcode.app. There was no longer this error message, and was able to inspect variables at a swift program breakpoint in Swift context, including po symbol.
Impact
Effectively this makes the debugger in Swift on Xcode projects on my systems essentially unable to inspect Swift contexts' state.
A few years ago [1] Xcode added new warnings that help detect a nasty gotcha related to the lifetime of unsafe pointers. For example:
Initialization of 'UnsafeMutablePointer<timeval>' results in a dangling pointer
Inout expression creates a temporary pointer, but argument 'iov_base' should be a pointer that outlives the call to 'init(iov_base:iov_len:)'
I’ve seen a lot of folks confused by these warnings, and by the lifetime of unsafe pointers in general, and this post is my attempt to clarify the topic.
If you have questions about any of this, please put them in a new thread in the Programming Languages > Swift topic.
Finally, I encourage you to watch the following WWDC presentations:
WWDC 2020 Session 10648 Unsafe Swift
WWDC 2020 Session 10167 Safely manage pointers in Swift
These cover some of the same ground I’ve covered here, and a lot of other cool stuff as well.
Share and Enjoy
—
Quinn “The Eskimo!”
Apple Developer Relations, Developer Technical Support, Core OS/Hardware
let myEmail = "eskimo" + "1" + "@apple.com"
[1] Swift 5.2.2, as shipped in Xcode 11.4. See the discussion of SR-2790 in Xcode 11.4 Release Notes.
Basics
In Swift, the ampersand (&) indicates that a parameter is being passed inout. Consider this example:
func addVarnish(_ product: inout String) {
product += " varnish"
}
var waffle = "waffle"
addVarnish(&waffle) // line A
print(waffle)
// printed: waffle varnish
On line A, the ampersand tells you that waffle could be modified by addVarnish(_:).
However, there is another use of ampersand that was designed to help with C interoperability. Consider this code:
var tv = timeval()
gettimeofday(&tv, nil)
print(tv)
// printed: timeval(tv_sec: 1590743104, tv_usec: 77027)
The first parameter to gettimeofday is an UnsafeMutablePointer<timeval>. Here the ampersand denotes a conversion from a timeval to an UnsafeMutablePointer<timeval>. This conversion makes it much easier to call common C APIs from Swift.
This also works for array values. For example:
var hostName = [CChar](repeating: 0, count: 256)
gethostname(&hostName, hostName.count)
print(String(cString: hostName))
// printed: slimey.local.
In this code the ampersand denotes a conversion from [CChar] to an UnsafeMutablePointer<CChar> that points to the base of the array.
While this is convenient, it’s potentially misleading, especially if you come from a C background. In C-based languages, using ampersand in this way yields a pointer to the value that’s valid until the value gets deallocated. That’s not the case in Swift. Rather, the pointer generated by the ampersand syntax is only valid for the duration of that function call.
To understand why that’s the case, consider this code:
struct TimeInTwoParts {
var sec: time_t = 0
var usec: Int32 = 0
var combined: timeval {
get { timeval(tv_sec: sec, tv_usec: usec) }
set {
sec = newValue.tv_sec
usec = newValue.tv_usec
}
}
}
var time = TimeInTwoParts()
gettimeofday(&time.combined, nil) // line A
print(time.combined)
// printed: timeval(tv_sec: 1590743484, tv_usec: 89118)
print(time.sec)
// printed: 1590743484
print(time.usec)
// printed: 89118
Here combined is a computed property that has no independent existence in memory. Thus, it simply makes no sense to take the address of it.
So, how does ampersand deal with this? Under the covers the Swift compiler expands line A to something like this:
var tmp = time.combined
gettimeofday(&tmp, nil)
time.combined = tmp
Once you understand this it’s clear why the resulting pointer is only valid for the duration of the call: As soon as Swift cleans up tmp, the pointer becomes invalid.
A Gotcha
This automatic conversion can be a nasty gotcha. Consider this code:
var tv = timeval()
let tvPtr = UnsafeMutablePointer(&tv) // line A
// ^~~~~~~~~~~~~~~~~~~~~~~~~
// Initialization of 'UnsafeMutablePointer<timeval>' results in a dangling pointer
gettimeofday(tvPtr, nil) // line B
This results in undefined behaviour because the pointer generated by the ampersand on line A is no longer valid when it’s used on line B. In some cases, like this one, the later Swift compiler is able to detect this problem and warn you about it. In other cases you’re not so lucky. Consider this code:
guard let f = fopen("tmp.txt", "w") else { … }
var buf = [CChar](repeating: 0, count: 1024)
setvbuf(f, &buf, _IOFBF, buf.count) // line A
let message = [UInt8]("Hello Crueld World!".utf8)
fwrite(message, message.count, 1, f) // line B
fclose(f) // line C
This uses setvbuf to apply a custom buffer to the file handle. The file handle uses this buffer until after the close on line C. However, the pointer created by the ampersand on line A only exists for the duration of the setvbuf call. When the code calls fwrite on line B the buffer pointer is no longer valid and things end badly.
Unfortunately the compiler isn’t able to detect this problem. Worse yet, the code might actually work initially, and then stop working as you change optimisation settings, update the compiler, change unrelated code, and so on.
Another Gotcha
There is another gotcha associated with the ampersand syntax. Consider this code:
class AtomicCounter {
var count: Int32 = 0
func increment() {
OSAtomicAdd32(1, &count)
}
}
This looks like it’ll implement an atomic counter but there’s no guarantee that the counter will be atomic. To understand why, apply the tmp transform from earlier:
class AtomicCounter {
var count: Int32 = 0
func increment() {
var tmp = count
OSAtomicAdd32(1, &tmp)
count = tmp
}
}
So each call to OSAtomicAdd32 could potentially be operating on a separate copy of the counter that’s then assigned back to count. This undermines the whole notion of atomicity.
Again, this might work in some builds of your product and then fail in other builds.
Note The above discussion is now theoretical because Swift 6 added a Synchronization module that includes comprehensive support for atomics. That module also has a Mutex type (if you need a mutex on older platforms, check out OSAllocatedUnfairLock). These constructs use various different mechanisms to ensure that the underlying value has a stable address.
Summary
So, to summarise:
Swift’s ampersand syntax has very different semantics from the equivalent syntax in C.
When you use an ampersand to convert from a value to a pointer as part of a function call, make sure that the called function doesn’t use the pointer after it’s returned.
It is not safe to use the ampersand syntax for functions where the exact pointer matters.
It’s Not Just Ampersands
There’s one further gotcha related to arrays. The gethostname example above shows that you can use an ampersand to pass the base address of an array to a function that takes a mutable pointer. Swift supports two other implicit conversions like this:
From String to UnsafePointer<CChar> — This allows you to pass a Swift string to an API that takes a C string. For example:
let greeting = "Hello Cruel World!"
let greetingLength = strlen(greeting)
print(greetingLength)
// printed: 18
From Array<Element> to UnsafePointer<Element> — This allows you to pass a Swift array to a C API that takes an array (in C, arrays are typically represented as a base pointer and a length). For example:
let charsUTF16: [UniChar] = [72, 101, 108, 108, 111, 32, 67, 114, 117, 101, 108, 32, 87, 111, 114, 108, 100, 33]
print(charsUTF16)
let str = CFStringCreateWithCharacters(nil, charsUTF16, charsUTF16.count)!
print(str)
// prints: Hello Cruel World!
Note that there’s no ampersand in either of these examples. This technique only works for UnsafePointer parameters (as opposed to UnsafeMutablePointer parameters), so the called function can’t modify its buffer. As the ampersand is there to indicate that the value might be modified, it’s not used in this immutable case.
However, the same pointer lifetime restriction applies: The pointer passed to the function is only valid for the duration of that function call. If the function keeps a copy of that pointer and then uses it later on, Bad Things™ will happen.
Consider this code:
func printAfterDelay(_ str: UnsafePointer<CChar>) {
print(strlen(str))
// printed: 18
DispatchQueue.main.asyncAfter(deadline: .now() + 1.0) {
print(strlen(str))
// printed: 0
}
}
let greeting = ["Hello", "Cruel", "World!"].joined(separator: " ")
printAfterDelay(greeting)
dispatchMain()
The second call to strlen yields undefined behaviour because the pointer passed to printAfterDelay(_:) becomes invalid once printAfterDelay(_:) returns. In this specific example the memory pointed to by str happened to contain a zero, and hence strlen returned 0 but that’s not guaranteed. The str pointer is dangling, so you might get any result from strlen, including a crash.
Advice
So, what can you do about this? There’s two basic strategies here:
Extend the lifetime of the pointer
Manual memory management
Extending the Pointer’s Lifetime
The first strategy makes sense when you have a limited number of pointers and their lifespan is limited. For example, you can fix the setvbuf code from above by changing it to:
let message = [UInt8]("Hello Crueld World!".utf8)
guard let f = fopen("tmp.txt", "w") else { … }
var buf = [CChar](repeating: 0, count: 1024)
buf.withUnsafeMutableBufferPointer { buf in
setvbuf(f, buf.baseAddress!, _IOFBF, buf.count)
fwrite(message, message.count, 1, f)
fclose(f)
}
This version of the code uses withUnsafeMutableBufferPointer(_:). That calls the supplied closure and passes it a pointer (actually an UnsafeMutableBufferPointer) that’s valid for the duration of that closure. As long as you only use that pointer inside the closure, you’re safe!
There are a variety of other routines like withUnsafeMutableBufferPointer(_:), including:
The withUnsafeMutablePointer(to:_:) function
The withUnsafeBufferPointer(_:), withUnsafeMutableBufferPointer(_:), withUnsafeBytes(_:), and withUnsafeMutableBytes(_:) methods on Array
The withUnsafeBytes(_:) and withUnsafeMutableBytes(_:) methods on Data
The withCString(_:) and withUTF8(_:) methods on String.
Manual Memory Management
If you have to wrangle an unbounded number of pointers — or the lifetime of your pointer isn’t simple, for example when calling an asynchronous call — you must revert to manual memory management. Consider the following code, which is a Swift-friendly wrapper around posix_spawn:
func spawn(arguments: [String]) throws -> pid_t {
var argv = arguments.map { arg -> UnsafeMutablePointer<CChar>? in
strdup(arg)
}
argv.append(nil)
defer {
argv.forEach { free($0) }
}
var pid: pid_t = 0
let success = posix_spawn(&pid, argv[0], nil, nil, argv, environ) == 0
guard success else { throw NSError(domain: NSPOSIXErrorDomain, code: Int(errno), userInfo: nil) }
return pid
}
This code can’t use the withCString(_:) method on String because it has to deal with an arbitrary number of strings. Instead, it uses strdup to copy each string to its own manually managed buffer. And, as these buffers are manually managed, is has to remember to free them.
Change History
2024-12-11 Added a note about the Synchronization module. Made various editorial changes.
2021-02-24 Fixed the formatting. Added links to the WWDC 2021 sessions. Fixed the feedback advice. Minor editorial changes.
2020-06-01 Initial version.
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?
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.
Hello guys!
I faced a problem with building...
My device suddenly updated to iOS 15.4.1, my Xcode was 13.2 and I had to update it to the latest version (13.3.1) to build the app. After the update, I had a few problems which were successfully solved but one of them stopped me for a few hours. The problem is with Bridging Headers or Swift Compiler, I really don't know what I did badly, and what causes problems.
On several forums I often read that is important to set:
Build Settings > Build Options > Build Libraries for Distribution
But in any case it doesn't work, on yes:
error: using bridging headers with module interfaces is unsupported
on no:
(line with import framework SWXMLHash) /Users/blablabla/SSLModel.swift:9:8: error: module compiled with Swift 5.5.1 cannot be imported by the Swift 5.6 compiler: /Users/blablabla2/Build/Products/Debug-iphoneos/SWXMLHash.framework/Modules/SWXMLHash.swiftmodule/arm64-apple-ios.swiftmodule
import SWXMLHash
It will be important that I use Carthage.
What should I do?
Clone all 10 frameworks that I use and re-build them with a new Xcode which includes compiler 5.6? That may be a bad solution... Any answers on similar topics don't help..
Is it ok for an Actor type to have a Publisher as a property to let others observe changes over time? Or use the @Published property wrapper to achieve this?
actor MyActor {
var publisher = PassthroughSubject<Int, Never>()
var data: Int {
didSet {
publisher.send(data)
}
}
...
}
// Usage
var tasks = Set<AnyCancellable>()
let actor = MyActor()
Task {
let publisher = await actor.publisher
publisher.sink { print($0) }.store(in: &tasks)
}
This seems like this should be acceptable. I would expect a Publisher to be thread safe, and as long as the Output is a value type things should be fine.
I have been getting random EXC_BAD_ACCESS errors when using this approach. But turning on the address sanitizer causes these crashes to go away. I know that isn't very specific but I wanted to start by seeing if this type of pattern is ok to do.
Recently I updated to Xcode 14.0. I am building an iOS app to convert recorded audio into text. I got an exception while testing the application from the simulator(iOS 16.0).
[SpeechFramework] -[SFSpeechRecognitionTask handleSpeechRecognitionDidFailWithError:]_block_invoke Ignoring subsequent recongition error: Error Domain=kAFAssistantErrorDomain Code=1101 "(null)"
Error Domain=kAFAssistantErrorDomain Code=1107 "(null)"
I have to know what does the error code means and why this error occurred.
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?
Hello,
It is mentioned in CryptoTokenKit documentation:
You use the CryptoTokenKit framework to easily access cryptographic tokens. Tokens are physical devices built in to the system, located on attached hardware (like a smart card), or accessible through a network connection.
However, it looks like there is lack of documentation with simple example, how to access network token.
I have a certificates in HSM (hardware secure module), which is accessible on network, and I'd like to access certificates on HSM on my Mac.
Does anybody know, where to start with implementation?
Thank you.
Getting this error several times when presenting a modal window over my splitview window when running it on my Mac using Swift/Mac Catalyst in XCode 14.2. When I click the Cancel button in the window then I get Scene destruction request failed with error: (null) right after an unwind segue.
2023-07-04 16:50:45.488538-0500 Recipes[27836:1295134] [WindowHosting] UIScene property of UINSSceneViewController was accessed before it was set.
2023-07-04 16:50:45.488972-0500 Recipes[27836:1295134] [WindowHosting] UIScene property of UINSSceneViewController was accessed before it was set.
2023-07-04 16:50:45.496702-0500 Recipes[27836:1295134] [WindowHosting] UIScene property of UINSSceneViewController was accessed before it was set.
2023-07-04 16:50:45.496800-0500 Recipes[27836:1295134] [WindowHosting] UIScene property of UINSSceneViewController was accessed before it was set.
2023-07-04 16:50:45.994147-0500 Recipes[27836:1295134] Unbalanced calls to begin/end appearance transitions for <UINavigationController: 0x7f7fdf068a00>.
bleep
2023-07-04 16:51:00.655233-0500 Recipes[27836:1297298] Scene destruction request failed with error: (null)
I don't quite understand what all all this means. (The "bleep" was a debugging print code I put in the unwind segue). I'm working through Apple's Mac Catalyst tutorial but it seems to be riddled with bugs and coding issues, even in the final part of the completed app which I dowmloaded and ran. I don't see these problems on IPad simulator.
I don't know if it's because Catalyst has problems itself or there's something else going on that I can fix myself. Any insight into these errors would be very much appreciated!
PS: The app seems to run ok on Mac without crashing despite the muliple issues
I am using Xcode 15 and working on a localised app. I use the new String Catalogs feature which works great for my app. In my app I created some local package like Apple has done it in the Backyard Birds example. However the translations I did in the package's String Catalog won’t be used in the app. What am I doing wrong?
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?
Is there any way to use metal-cpp in a Swift project? I have a platform layer I've written in Swift that handles Window/View creation, as well as event handling, etc. I've been trying to bridge this layer with my C++ layer as you normally would using a pure C interface, but using Metal instances that cross this boundary just doesn't seem to work.
e.g. Currently I initialize a CAMetalLayer for my NSView, setting that as the layer for the view. I've tried passing this Metal layer into my C++ code via a void* pointer through a C interface, and then casting it to a CA::MetalView to be used. When this didn't work, I tried creating the CA::MetalLayer in C++ and passing that back to the Swift layer as a void* pointer, then binding it to a CAMetalLayer type. And of course, this didn't work either.
So are the options for metal-cpp to use either Objective-C or just pure C++ (using AppKit.hpp)? Or am I missing something for how to integrate with Swift?
I am writing a SPM based project for MacOS. In this project? I need to access MacOS Keychain.
I am write a swift test built by SPM testTarget(). I can see it generates a bundle ./.build/x86_64-apple-macosx/debug/MyProjectTests.xctest with an executable:
% file ./.build/x86_64-apple-macosx/debug/MyProjectPackageTests.xctest/Contents/MacOS/MyProjectPackageTests
./.build/x86_64-apple-macosx/debug/MyProjectPackageTests.xctest/Contents/MacOS/MyProjectPackageTests: Mach-O 64-bit bundle x86_64
This bundle file cannot be executed. How can I execute its tests?
I tried with xcodebuild test-without-building -xctestrun ./.build/x86_64-apple-macosx/debug/MyProjectPackageTests.xctest -destination 'platform=macOS' without any chance.
Obviously the next question is can I 'simply' add entitlement to this bundle with codesign to fix my enttilement error.
My error when running the test is A required entitlement isn't present.
Hi, I'm relatively new to iOS development and kindly ask for some feedback on a strategy to achieve this desired behavior in my app.
My Question:
What would be the best strategy for sound effect playback when an app is in the background with precise timing? Is this even possible?
Context:
I created a basic countdown timer app (targeting iOS 17 with Swift/SwiftUI.). Countdown sessions can last up to 30-60 mins. When the timer is started it progresses through a series of sub-intervals and plays a short sound for each one. I used AVAudioPlayer and everything works fine when the app is in the foreground. I'm considering switching to AVAudioEngine b/c precise timing is very important and the AIs tell me this would have better precision.
I'm already setting "App plays audio or streams audio/video using AirPlay" in my Plist, and have configured:
AVAudioSession.sharedInstance().setCategory(.playback, mode: .default, options: .mixWithOthers)
Curiously, when testing on my iPhone 13 mini, sounds sometimes still play when the app is in the background, but not always.
What I've considered:
Background Tasks: Would they make any sense for this use-case? Seems like not if the allowed time is short & limited by the system.
Pre-scheduling all Sounds: Not sure this would even work and seems like a lot of memory would be needed (could be hundreds of intervals).
ActivityKit Alerts: works but with a ~50ms delay which is too long for my purposes.
Pre-Render all SFX to 1 large audio file: Seems like a lot of work and processing time and probably not worth it. I hope there's a better solution.
I'd really appreciate any feedback.
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?
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'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?