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Access essential data types, collections, and operating-system services to define the base layer of functionality for your app using Foundation.

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Locale.Script seems to be returning a value even though the language has no script
We just dropped support for iOS 16 in our app and migrated to the new properties on Locale to extract the language code, region, and script. However, after doing this we are seeing an issue where the script property is returning a value when the language has no script. Here is the initializer that we are using to populate the values. The identifier is coming from the preferredLanguages property that is found on Locale. init?(identifier: String) { let locale = Locale(identifier: identifier) guard let languageCode = locale.language.languageCode?.identifier else { return nil } language = languageCode region = locale.region?.identifier script = locale.language.script?.identifier } Whenever I inspect locale.language I see all of the correct values. However, when I inspect locale.language.script directly it is always returning Latn as the value. If I inspect the deprecated locale.scriptCode property it will return nil as expected. Here is an example from the debugger for en-AU. I also see the same for other languages such as en-AE, pt-BR. Since the language components show the script as nil, then I would expect locale.language.script?.identifier to also return nil.
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122
Jun ’25
Feedback/issues for SwiftData custom store
Hello, thank you Apple for supporting custom store with SwiftData and the Schema type is superb to work with. I have successfully set one up with SQL and have some feedback and issues regarding its APIs. There’s a highlighted message in the documentation about not using internal restricted symbols directly, but they contradict with the given protocols and I am concerned about breaking any App Store rules. Are we allowed to use these? If not, they should be opened up as they’re useful. BackingData is required to set up custom snapshots, initialization, and getting/setting values. And I want to use it with createBackingData() to directly initialize instances from snapshots when transferring them between server and client or concurrency. RelationshipCollection for casting to-many relationships from backing data or checking if an array contains a PersistentModel. SchemaProperty for type erasure in a collection. Schema.Relationship has KeyPath properties, but it is missing for Schema.Attribute and Schema.CompositeAttribute. Which means you can’t purely depend on the schema to map data. I am unable to access the properties of a custom struct type in a predicate unless I use Mirror with schemaMetadata() or CustomStringConvertible on the KeyPath directly to extract it. Trivial, but… the KeyPath property name is inconsistent (it’s all lowercase). It would be nice to retrieve property names from custom struct types, since you are unable access CodingKeys that are auto synthesized by Codable for structs. But I recently realized they’re a part Schema.CompositeAttribute, however I don’t know how to match these without the KeyPath… I currently map my entities using CodingKeys to their PredicateCodableKeyPathProviding.… but I wish for a simpler alternative! It’s unclear how to provide the schema to the snapshot before new models are created. I currently use a static property, but I want to make it flexible if more schemas and configurations are added later on. I considered saving and loading the schema in a temporary location, but doubtful that the KeyPath values will be available as they are not Codable. I suspect schemaMetadata() has the information I need to map the backing data without a schema for snapshots, but as mentioned previously, properties are inaccessible… Allow access to entity metatypes, like value types from SchemaProperty. They’re useful for getting data out of snapshots and casting them to CodingKeys and PredicateCodableKeyPathProviding. They do not carry over when you provide them in the Schema. I am unable to retrieve the primary key from PersistentIdentifier. It seems like once you create one, you can’t get it out, like the DataStoreConfiguration in ModelContainer is not the one you used to set it up. I cannot cast it, it is an entirely different struct? I have to use JSONSerialization to extract it, but I want to get it directly since it is not a column in my database. It is transformed when it goes to/from my tables. It’s unknown how to support some schema options, such as Spotlight and CloudKit. Allow for extending macro options, such as adding options to set as primary key, whether to auto increment, etc… You can create a schema for super and sub entities, but it doesn’t appear you can actually set them up from the @Model macro or use inheritance on these models… SwiftData history tracking seems incomplete for HistoryDelete, because that protocol requires HistoryTombstone, but this type cannot be instantiated, nor does it contain anything useful to infer from. As an aside, I want to create my own custom ModelActor that is a global actor. However, I’m unable to replicate the executor that Apple provides where the executor has a ModelContext, because this type does not conform to Sendable. So how did Apple do this? The documentation doesn’t mention unchecked Sendable, but I figure if the protocol is available then we would be able to set up our own. And please add concurrency features! Anyway, I hope for more continued support in the future and I am looking forward to what’s new this WWDC! 😊
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143
May ’25
How to delete cookies on IOS18
Hello, I have encountered an issue with an iPhone 15PM with iOS 18.5. The NSHTTPCookieStorage failed to clear cookies, but even after clearing them, I was still able to retrieve them. However, on the same system It is normal on iPhone 14PM. I would like to know the specific reason and whether there are any adaptation related issues. Following code: NSHTTPCookie *cookie; NSHTTPCookieStorage *storage = [NSHTTPCookieStorage sharedHTTPCookieStorage]; for (cookie in [storage cookies]) { [storage deleteCookie:cookie]; }
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148
May ’25
Can I use @_implementationOnly import in my Framework
We have FrameworkA which needs to use another FrameworkB internally to fetch a token. Now when I try to use this FrameworkA, we are seeing an issue with internal framework i.e. No such module 'FrameworkB'. But when I use @_implementationOnly import for the internal FrameworkB, I didn't see any issues. So just wanted to check If I can go ahead and use this @_implementationOnly import flag in Production?
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124
May ’25
Key-value storage will not sync data past a certain size
I have an app which uses key-value storage and will not sync data past a certain size -- meaning that device "A" will send the data to the cloud but device "B" will never receive the updated data. Device "B" will receive the NSUbiquitousKeyValueStoreDidChangeExternallyNotification that the KVS changed but the data is empty. The data in in the KVS is comprised of 4 keys, each containing a value of NSData generated by NSKeyedArchiver. The NSData is comprised of property-list data types (e.g. numbers, strings, dates, etc.) I've verified that the KVS meets the limits of: A total of 1 MB per app, with a per-key limit of 1 MB A per-key value size limit of 1 MB, and a maximum of 1024 keys A maximum length for key strings is 64 bytes using UTF8 encoding Also, the app has never received an NSUbiquitousKeyValueStoreQuotaViolationChange notification. Of the 4 keys, 3 of them contain no more than 30 KB of data each. However, one of the keys can contain as much as 160 KB of data which will not sync to another device. Strangely, if I constrain the data to 100 KB it will work, however, that is not ideal as it is a fraction of the necessary data. I don't see any errors in the debug log either. Any suggestions on what to try next to get this working?
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158
May ’25
Getting Progress from long running process
I have been working on updating an old app that makes extensive use of Objective-C's NSTask. Now using Process in Swift, I'm trying to gather updates as the process runs, using readabilityHandler and availableData. However, my process tends to exit before all data has been read. I found this post entitled "Running a Child Process with Standard Input and Output" but it doesn't seem to address gathering output from long-running tasks. Is there a straightforward way to gather ongoing output from a long running task without it prematurely exiting?
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170
May ’25
XPC Connection Error
I have an accessory with MFi authenticaiton passed(got 0xAA05) and identification accepted (got 0x1D02). But when I try to open the target stream by using iAP2 EA session framework, I always enounter the same error looking like: XPC connection error: Error Domain=NSCocoaErrorDomain Code=4099 "The connection to service named com.apple.accessories.externalaccessory-server was invalidated from this process." UserInfo={NSDebugDescription=The connection to service named com.apple.accessories.externalaccessory-server was invalidated from this process.} anybody can tell me what it related with? And what can I do to go through it quickly? Thank you much in advance.
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115
May ’25
Detecting Notification Banners, DND, and other screen anomalies
Is there a public method to know when an APNS has appeared on the screen? wrapping up a very high end photogrammetry app, using the front facing camera and screen illumination- incoming notifications completely throw off the math. Ideally, it would be great to turn on Do Not Disturb for the short process, but we’d settle for just the detection of the notification banner. also: extra credit - programattically adjusting Auto Dimming, and True Tone would be lovely too.
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56
May ’25
NSUserDefault issue after upgrading to iPadOS 17.7.7
Our app needs to read server settings that are configured in the app's settings. In iPadOS 17.7.7 specifically (iPadOS 17.7.6, iPadOS 18.5, and other versions works fine) one can't retrieve any setting from the settings bundle using: if ([[NSUserDefaults standardUserDefaults] objectForKey:@"setting_hostname"] != nil) serverHostname = [[NSUserDefaults standardUserDefaults] objectForKey:@"setting_hostname"]; Also, when writing a custom value in NSUserDefaults like: [[NSUserDefaults standardUserDefaults] setObject:@"Test" forKey:@"test"]; [[NSUserDefaults standardUserDefaults] synchronize]; NSString* test = [[NSUserDefaults standardUserDefaults] objectForKey:@"test"]; NSLog(@"%@", test); Shows an error in the console: Couldn't write values for keys ( test ) in CFPrefsPlistSource<0x3017ecc60> (Domain: <redacted_bundle_id>, User: kCFPreferencesCurrentUser, ByHost: No, Container: (null), Contents Need Refresh: No): setting these preferences requires user-preference-write or file-write-data sandbox access When closing the app and reopening it, and then reading the value of [[NSUserDefaults standardUserDefaults] objectForKey:@"test"]; returns null
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927
May ’25
URLSession download looping indefinitely until it times out
Hi, I’m trying to download a remote file in the background, but I keep getting a strange behaviour where URLSession download my file indefinitely during a few minutes, without calling urlSession(_:downloadTask:didFinishDownloadingTo:) until the download eventually times out. To find out that it’s looping, I’ve observed the total bytes written on disk by implementing urlSession(_:downloadTask:didWriteData:totalBytesWritten:totalBytesExpectedToWrite:). Note that I can't know the size of the file. The server is not able to calculate the size. Below is my implementation. I create an instance of URLSession like this: private lazy var session: URLSession = { let configuration = URLSessionConfiguration.background(withIdentifier: backgroundIdentifier) configuration.isDiscretionary = false configuration.sessionSendsLaunchEvents = true return URLSession(configuration: configuration, delegate: self, delegateQueue: nil) }() My service is using async/await so I have implemented an AsyncThrowingStream : private var downloadTask: URLSessionDownloadTask? private var continuation: AsyncThrowingStream&lt;(URL, URLResponse), Error&gt;.Continuation? private var stream: AsyncThrowingStream&lt;(URL, URLResponse), Error&gt; { AsyncThrowingStream&lt;(URL, URLResponse), Error&gt; { continuation in self.continuation = continuation self.continuation?.onTermination = { @Sendable [weak self] data in self?.downloadTask?.cancel() } downloadTask?.resume() } } Then to start the download, I do : private func download(with request: URLRequest) async throws -&gt; (URL, URLResponse) { do { downloadTask = session.downloadTask(with: request) for try await (url, response) in stream { return (url, response) } throw NetworkingError.couldNotBuildRequest } catch { throw error } } Then in the delegate : public func urlSession(_ session: URLSession, downloadTask: URLSessionDownloadTask, didFinishDownloadingTo location: URL) { guard let response = downloadTask.response, downloadTask.error == nil, (response as? HTTPURLResponse)?.statusCode == 200 else { continuation?.finish(throwing: downloadTask.error) return } do { let documentsURL = try FileManager.default.url(for: .documentDirectory, in: .userDomainMask, appropriateFor: nil, create: false) let savedURL = documentsURL.appendingPathComponent(location.lastPathComponent) try FileManager.default.moveItem(at: location, to: savedURL) continuation?.yield((savedURL, response)) continuation?.finish() } catch { continuation?.finish(throwing: error) } } I also tried to replace let configuration = URLSessionConfiguration.background(withIdentifier: backgroundIdentifier) by let configuration = URLSessionConfiguration.default and this time I get a different error at the end of the download: Task &lt;0457F755-9C52-4CFB-BDB2-F378D0C94912&gt;.&lt;1&gt; failed strict content length check - expected: 0, received: 530692, received (uncompressed): 0 Task &lt;0457F755-9C52-4CFB-BDB2-F378D0C94912&gt;.&lt;1&gt; finished with error [-1005] Error Domain=NSURLErrorDomain Code=-1005 "The network connection was lost." UserInfo={NSLocalizedDescription=The network connection was lost., NSErrorFailingURLStringKey=https:/&lt;host&gt;:8190/proxy?Func=downloadVideoByUrl&amp;SessionId=slufzwrMadvyJad8Lkmi9RUNAeqeq, NSErrorFailingURLKey=https://&lt;host&gt;:8190/proxy?Func=downloadVideoByUrl&amp;SessionId=slufzwrMadvyJad8Lkmi9RUNAeqeq, _NSURLErrorRelatedURLSessionTaskErrorKey=( "LocalDownloadTask &lt;0457F755-9C52-4CFB-BDB2-F378D0C94912&gt;.&lt;1&gt;" ), _NSURLErrorFailingURLSessionTaskErrorKey=LocalDownloadTask &lt;0457F755-9C52-4CFB-BDB2-F378D0C94912&gt;.&lt;1&gt;, NSUnderlyingError=0x300d9a7c0 {Error Domain=kCFErrorDomainCFNetwork Code=-1005 "(null)" UserInfo={NSErrorPeerAddressKey=&lt;CFData 0x302139db0 [0x1fcb1f598]&gt;{length = 16, capacity = 16, bytes = 0x10021ffe91e227500000000000000000}}}} The log "failed strict content length check” made me look into the response header, which has the following: content-length: 0 Content-Type: application/force-download Transfer-encoding: chunked Connection: KEEP-ALIVE Content-Transfer-Encoding: binary So it should be fine the way I setup my URLSession. The download works fine in Chrome/Safari/Chrome or Postman. My code used to work a couple of weeks before, so I expect something has changed on the server side, but I can’t find what, and I don’t get much help from the guys on the server side. Has anyone an idea of what’s going on?
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133
May ’25
URLSessionDownloadTaskDelegate functions not called when using URLSession.download(for:), but works when using URLSession.downloadTask(with:)
I'm struggling to understand why the async-await version of URLSession download task APIs do not call the delegate functions, whereas the old non-async version that returns a reference to the download task works just fine. Here is my sample code: class DownloadDelegate: NSObject, URLSessionDownloadDelegate { func urlSession(_ session: URLSession, downloadTask: URLSessionDownloadTask, didWriteData bytesWritten: Int64, totalBytesWritten: Int64, totalBytesExpectedToWrite: Int64) { // This only prints the percentage of the download progress. let calculatedProgress = Float(totalBytesWritten) / Float(totalBytesExpectedToWrite) let formatter = NumberFormatter() formatter.numberStyle = .percent print(formatter.string(from: NSNumber(value: calculatedProgress))!) } } // Here's the VC. final class DownloadsViewController: UIViewController { private let url = URL(string: "https://pixabay.com/get/g0b9fa2936ff6a5078ea607398665e8151fc0c10df7db5c093e543314b883755ecd43eda2b7b5178a7e613a35541be6486885fb4a55d0777ba949aedccc807d8c_1280.jpg")! private let delegate = DownloadDelegate() private lazy var session = URLSession(configuration: .default, delegate: delegate, delegateQueue: nil) // for the async-await version private var task: Task&lt;Void, Never&gt;? // for the old version private var downloadTask: URLSessionDownloadTask? override func viewWillAppear(_ animated: Bool) { super.viewWillAppear(animated) task?.cancel() task = nil task = Task { let (_, _) = try! await session.download(for: URLRequest(url: url)) self.task = nil } // If I uncomment this, the progress listener delegate function above is called. // downloadTask?.cancel() // downloadTask = nil // downloadTask = session.downloadTask(with: URLRequest(url: url)) // downloadTask?.resume() } } What am I missing here?
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2k
May ’25
NSMetadataQuery not searching subdirectories in external ubiquity container
Testing Environment: iOS 18.4.1 / macOS 15.4.1 I am working on an iOS project that aims to utilize the user's iCloud Drive documents directory to save a specific directory-based file structure. Essentially, the app would create a root directory where the user chooses in iCloud Drive, then it would populate user generated files in various levels of nested directories. I have been attempting to use NSMetadataQuery with various predicates and search scopes but haven't been able to get it to directly monitor changes to files or directories that are not in the root directory. Instead, it only monitors files or directories in the root directory, and any changes in a subdirectory are considered an update to the direct children of the root directory. Example iCloud Drive Documents (Not app's ubiquity container) User Created Root Directory (Being monitored) File A Directory A File B An insertion or deletion within Directory A would only return a notification with userInfo containing data for NSMetadataQueryUpdateChangedItemsKey relating to Directory A, and not the file or directory itself that was inserted or deleted. (Query results array also only contain the direct children.) I have tried all combinations of these search scopes and predicates with no luck: query.searchScopes = [ rootDirectoryURL, NSMetadataQueryUbiquitousDocumentsScope, NSMetadataQueryAccessibleUbiquitousExternalDocumentsScope, ] NSPredicate(value: true) NSPredicate(format: "%K LIKE '*.md'", NSMetadataItemFSNameKey) NSPredicate(format: "%K BEGINSWITH %@", NSMetadataItemPathKey, url.path(percentEncoded: false)) I do see these warnings in the console upon starting my query: [CRIT] UNREACHABLE: failed to get container URL for com.apple.CloudDocs [ERROR] couldn't fetch remote operation IDs: NSError: Cocoa 257 "The file couldn’t be opened because you don’t have permission to view it." "Error returned from daemon: Error Domain=com.apple.accounts Code=7 "(null)"" But I am not sure what to make of that, since it does act normally for finding updates in the root directory. Hopefully this isn't a limitation of the API, as the only alternative I could think of would be to have multiple queries running for each nested directory that I needed updates for.
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125
May ’25
Custom @Observable RandomAcccessCollection List/ForEach issues
I'm trying to understand the behavior I'm seeing here. In the following example, I have a custom @Observable class that adopts RandomAccessCollection and am attempting to populate a List with it. If I use an inner collection property of the instance (even computed as this shows), the top view identifies additions to the list. However, if I just use the list as a collection in its own right, it detects when a change is made, but not that the change increased the length of the list. If you add text that has capital letters you'll see them get sorted correctly, but the lower list retains its prior count. The choice of a List initializer with the model versus an inner ForEach doesn't change the outcome, btw. If I cast that type as an Array(), effectively copying its contents, it works fine which leads me to believe there is some additional Array protocol conformance that I'm missing, but that would be unfortunate since I'm not sure how I would have known that. Any ideas what's going on here? The new type can be used with for-in scenarios fine and compiles great with List/ForEach, but has this issue. I'd like the type to not require extra nonsense to be used like an array here. import SwiftUI fileprivate struct _VExpObservable6: View { @Binding var model: ExpModel @State private var text: String = "" var body: some View { NavigationStack { VStack(spacing: 20) { Spacer() .frame(height: 40) HStack { TextField("Item", text: $text) .textFieldStyle(.roundedBorder) .textContentType(.none) .textCase(.none) Button("Add Item") { guard !text.isEmpty else { return } model.addItem(text) text = "" print("updated model #2 using \(Array(model.indices)):") for s in model { print("- \(s)") } } } InnerView(model: model) OuterView(model: model) } .listStyle(.plain) .padding() } } } // - displays the model data using an inner property expressed as // a collection. fileprivate struct InnerView: View { let model: ExpModel var body: some View { VStack { Text("Model Inner Collection:") .font(.title3) List { ForEach(model.sorted, id: \.self) { item in Text("- \(item)") } } .border(.darkGray) } } } // - displays the model using the model _as the collection_ fileprivate struct OuterView: View { let model: ExpModel var body: some View { VStack { Text("Model as Collection:") .font(.title3) // - the List/ForEach collections do not appear to work // by default using the @Observable model (RandomAccessCollection) // itself, unless it is cast as an Array here. List { // ForEach(Array(model), id: \.self) { item in ForEach(model, id: \.self) { item in Text("- \(item)") } } .border(.darkGray) } } } #Preview { @Previewable @State var model = ExpModel() _VExpObservable6(model: $model) } @Observable fileprivate final class ExpModel: RandomAccessCollection { typealias Element = String var startIndex: Int { 0 } var endIndex: Int { sorted.count } init() { _listData = ["apple", "yellow", "about"] } subscript(_ position: Int) -> String { sortedData()[position] } var sorted: [String] { sortedData() } func addItem(_ item: String) { _listData.append(item) _sorted = nil } private var _listData: [String] private var _sorted: [String]? private func sortedData() -> [String] { if let ret = _sorted { return ret } let ret = _listData.sorted() _sorted = ret return ret } }
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102
Apr ’25
Running a Child Process with Standard Input and Output
IMPORTANT Rather than use the code below, I recommend that you adopt Swift’s shiny-new Subprocess package. That’s what I’m doing! (-: Running a child process using Process (or NSTask in Objective-C) is easy, but piping data to and from the child’s stdin and stdout is surprisingly tricky. I regularly see folks confused by this. Moreover, it’s easy to come up with a solution that works most of the time, but suffers from weird problems that only show up in the field [1]. I recently had a couple of DTS incidents from folks struggling with this, so I sat down and worked through the details. Pasted below is the results of that effort, namely, a single function that will start a child process, pass it some data on stdin, read the data from the child’s stdout, and call a completion handler when everything is done. There are some things to note here, some obvious, some not so much: I’ve included Swift and Objective-C versions of the code. Both versions work the same way. The Swift version has all the comments. If you decide to base your code on the Objective-C version, copy the comments from there. I didn’t bother collecting stderr. That’s not necessary in many cases and, if you need it, it’s not hard to extend the code to handle that case. I use Dispatch I/O rather than FileHandle to manage the I/O channels. Dispatch I/O is well suited to this task. In contrast, FileHandle has numerous problems working with pipes. For the details, see Whither FileHandle?. This single function is way longer than I’d normally tolerate. This is partly due to the extensive comments and party due to my desire to maintain focus. When wrapping Process it’s very easy to run afoul of architecture astronaut-ism. Indeed, I have a much more full-featured Process wrapper sitting on my hard disk, but that’s going to stay there in favour of this approach (-: Handling a child process correctly involves some gnarly race conditions. The code has extensive comments explaining how I deal with those. If you have any questions or comments about this, put them in a new thread. Make sure to tag that thread with Foundation and Inter-process communication so that I see it. Share and Enjoy — Quinn “The Eskimo!” @ Developer Technical Support @ Apple let myEmail = "eskimo" + "1" + "@" + "apple.com" [1] Indeed, this post shows that I’ve made this sort of mistake myself )-:
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7.8k
Apr ’25
Proper way to create an AppleEvent record descriptor from NSDictionary
When using NSScriptCommand, is there any way to create an NSAppleEventDescriptor from an NSDictionary with arbitrary keys without using keyASUserRecordFields? Am I correct in thinking that this constant is deprecated? I ask because there is still active documentation using it. Is there another way to return a record where the keys aren't known at compile-time?
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90
Apr ’25