General: Forums subtopic: App & System Services > Networking TN3151 Choosing the right networking API Networking Overview document — Despite the fact that this is in the archive, this is still really useful. TLS for App Developers forums post Choosing a Network Debugging Tool documentation WWDC 2019 Session 712 Advances in Networking, Part 1 — This explains the concept of constrained networking, which is Apple’s preferred solution to questions like How do I check whether I’m on Wi-Fi? TN3135 Low-level networking on watchOS TN3179 Understanding local network privacy Adapt to changing network conditions tech talk Understanding Also-Ran Connections forums post Extra-ordinary Networking forums post Foundation networking: Forums tags: Foundation, CFNetwork URL Loading System documentation — NSURLSession, or URLSession in Swift, is the recommended API for HTTP[S] on Apple platforms. Moving to Fewer, Larger Transfers forums post Testing Background Session Code forums post Network framework: Forums tag: Network Network framework documentation — Network framework is the recommended API for TCP, UDP, and QUIC on Apple platforms. Building a custom peer-to-peer protocol sample code (aka TicTacToe) Implementing netcat with Network Framework sample code (aka nwcat) Configuring a Wi-Fi accessory to join a network sample code Moving from Multipeer Connectivity to Network Framework forums post NWEndpoint History and Advice forums post Wi-Fi (general): How to modernize your captive network developer news post Wi-Fi Fundamentals forums post Filing a Wi-Fi Bug Report forums post Working with a Wi-Fi Accessory forums post — This is part of the Extra-ordinary Networking series. Wi-Fi (iOS): TN3111 iOS Wi-Fi API overview technote Wi-Fi Aware framework documentation WirelessInsights framework documentation iOS Network Signal Strength forums post Network Extension Resources Wi-Fi on macOS: Forums tag: Core WLAN Core WLAN framework documentation Secure networking: Forums tags: Security Apple Platform Security support document Preventing Insecure Network Connections documentation — This is all about App Transport Security (ATS). WWDC 2017 Session 701 Your Apps and Evolving Network Security Standards [1] — This is generally interesting, but the section starting at 17:40 is, AFAIK, the best information from Apple about how certificate revocation works on modern systems. Available trusted root certificates for Apple operating systems support article Requirements for trusted certificates in iOS 13 and macOS 10.15 support article About upcoming limits on trusted certificates support article Apple’s Certificate Transparency policy support article What’s new for enterprise in iOS 18 support article — This discusses new key usage requirements. Technote 2232 HTTPS Server Trust Evaluation Technote 2326 Creating Certificates for TLS Testing QA1948 HTTPS and Test Servers Miscellaneous: More network-related forums tags: 5G, QUIC, Bonjour On FTP forums post Using the Multicast Networking Additional Capability forums post Investigating Network Latency Problems forums post Share and Enjoy — Quinn “The Eskimo!” @ Developer Technical Support @ Apple let myEmail = "eskimo" + "1" + "@" + "apple.com" [1] This video is no longer available from Apple, but the URL should help you locate other sources of this info.

I'm working on an API client for a REST service that uses a custom token-based authentiation scheme. The app hits a specificed authentication endpoint with a username and password, said endpoint returns a token that's good for X amount of time, and the app passes that token along with every subsequent request. When that token expires, we start over.Most literature out there tells me to manually set the Authorization header on my request, but official Apple documentation discourages this, as that header is meant to be 'owned' by the built-in HTTP loading system. That said, official documentation on the 'correct' way to do this is shockingly lacking, and the standard didReceiveChallenge callbacks seem better suited for non-custom Basic/Digest/etc authentication schemes. One thought I had was registering my own URLProtocol subclass to handle our custom flow. However, while I haven't had a chance to sit down and take a crack at that yet, my understanding from skimming these forums is that it's suffering from some bit-rot right now, so it 'might' (?) not be the best choice. That, and it's also not clear to me whether the rules around the Authorization header change when a custom URLProtocol is in play.So, community (paging eskimo in particular!), what's the correct way for me to go about this?

We are getting a crash _dispatch_assert_queue_fail when the cancellationHandler on NSProgress is called. We do not see this with iOS 17.x, only on iOS 18. We are building in Swift 6 language mode and do not have any compiler warnings. We have a type whose init looks something like this: init( request: URLRequest, destinationURL: URL, session: URLSession ) { progress = Progress() progress.kind = .file progress.fileOperationKind = .downloading progress.fileURL = destinationURL progress.pausingHandler = { [weak self] in self?.setIsPaused(true) } progress.resumingHandler = { [weak self] in self?.setIsPaused(false) } progress.cancellationHandler = { [weak self] in self?.cancel() } When the progress is cancelled, and the cancellation handler is invoked. We get the crash. The crash is not reproducible 100% of the time, but it happens significantly often. Especially after cleaning and rebuilding and running our tests. * thread #4, queue = 'com.apple.root.default-qos', stop reason = EXC_BREAKPOINT (code=1, subcode=0x18017b0e8) * frame #0: 0x000000018017b0e8 libdispatch.dylib`_dispatch_assert_queue_fail + 116 frame #1: 0x000000018017b074 libdispatch.dylib`dispatch_assert_queue + 188 frame #2: 0x00000002444c63e0 libswift_Concurrency.dylib`swift_task_isCurrentExecutorImpl(swift::SerialExecutorRef) + 284 frame #3: 0x000000010b80bd84 MyTests`closure #3 in MyController.init() at MyController.swift:0 frame #4: 0x000000010b80bb04 MyTests`thunk for @escaping @callee_guaranteed @Sendable () -> () at <compiler-generated>:0 frame #5: 0x00000001810276b0 Foundation`__20-[NSProgress cancel]_block_invoke_3 + 28 frame #6: 0x00000001801774ec libdispatch.dylib`_dispatch_call_block_and_release + 24 frame #7: 0x0000000180178de0 libdispatch.dylib`_dispatch_client_callout + 16 frame #8: 0x000000018018b7dc libdispatch.dylib`_dispatch_root_queue_drain + 1072 frame #9: 0x000000018018bf60 libdispatch.dylib`_dispatch_worker_thread2 + 232 frame #10: 0x00000001012a77d8 libsystem_pthread.dylib`_pthread_wqthread + 224 Any thoughts on why this is crashing and what we can do to work-around it? I have not been able to extract our code into a simple reproducible case yet. And I mostly see it when running our code in a testing environment (XCTest). Although I have been able to reproduce it running an app a few times, it's just less common.

Hi there, I uploaded an update bundle for the posted app, but I got a rejection message. ITMS-90048: This bundle is invalid - Your archive contains paths that are not allowed: [._Symbols] The XCode version I'm using is 16.2, and I've been trying to find a route using Run Script and Finder, but I don't know what the hell it is about. Does anybody know what could cause this issue? Any help would be appreciated. Thanks.

Upgraded to Tahoe 26.4 and Xcode 26.4 and realized Xcode is missing the documentation for Foundation. Occasionally, if other (not yet missing) documentation references a Foundation entity, such as a type, clicking on it may open in a web browser pointing to the externally hosted Apple documentation. Anyone else experiencing this or have a workaround (perhaps the documentation files are on disk but were somehow lost / disconnected from the Xcode doc browser)? I checked the release notes for 26.4 and for 26.3 but did not find a mention of anything like that. Filed an issue with Apple, please do too if you are affected so hopefully it will see some love and lead to restoring the documentation. Edited: found some possibly related files in my ~/Library and the newer version v302 (26.4 related, I think, is considerably smaller): du -sh ~/Library/Developer/Xcode/DocumentationCache/* | awk -F/ '{print $NF "\t" $1}' v296 1.0G v302 507M

I am using a URLSessionWebSocketTask. When trying to receive messages while the app is backgrounded, the receive() method fails with an NSError where the domain is NSPOSIXErrorDomain and the code is ECONNABORTED. That behavior is good. However, when this happens, the URLSessionWebSocketTask reports a closeCode of invalid, which is supposed to denote that the connection is still open. However, the connection state property is reporting completed. I feel that the closeCode property should be reporting something like abnormalClosure in this case. Either way, this seems like a bug or the documentation is incorrect.

Recently, some feedback has been received. After users upgrade to ipados 17.7.7 and return to the login status and restart the App, it will become invalid. We checked the log and found that the content stored in NSUserdefault would be lost after restarting the App. Has anyone encountered this problem?

We are developing an iOS application that is interacting with HTTP APIs that requires us to put a unique UUID (a nonce) as an header on every request (obviously there's more than that, but that's irrilevant to the question here). If the same nonce is sent on two subsequent requests the server returns a 412 error. We should avoid generating this kind of errors as, if repeated, they may be flagged as a malicious activity by the HTTP APIs. We are using URLSession.shared.dataTaskPublisher(for: request) to call the HTTP APIs with request being generated with the unique nonce as an header. On our field tests we are seeing a few cases of the same HTTP request (same nonce) being repeated a few seconds on after the other. Our code has some retry logic only on 401 errors, but that involves a token refresh, and this is not what we are seeing from logs. We were able to replicate this behaviour on our own device using Network Link Conditioner with very bad performance, with XCode's Network inspector attached we can be certain that two HTTP requests with identical headers are actually made automatically, the first request has an "End Reason" of "Retry", the second is "Success" with Status 412. Our questions are: can we disable this behaviour? can we provide a new request for the retry (so that we can update headers)? Thanks, Francesco

I have an iOS app with ExtensionFoundation. It runs well on my local device, but when I upload on the AppStore it gets rejected with: Validation failed Invalid Info.plist value. The value of the EXExtensionPointIdentifier key, AsheKube.app.a-Shell.localWebServer, in the Info.plist of “a-Shell.app/Extensions/localWebServer.appex” is invalid. Please refer to the App Extension Programming Guide at https://developer.apple.com/library/content/documentation/General/Conceptual/ExtensibilityPG/Action.html#/apple_ref/doc/uid/TP40014214-CH13-SW1. (ID: ae8dd1dd-8caf-4a48-9651-7a225faed4eb) The Info.plist in my Extension is: <?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd"> <plist version="1.0"> <dict> <key>EXAppExtensionAttributes</key> <dict> <key>EXExtensionPointIdentifier</key> <string>com.example.example-extension</string> </dict> </dict> </plist> so the Info.plist that causes the issue has been automatically generated by Xcode. I can access it as well, and it says: { "BuildMachineOSBuild" => "25A354" "CFBundleDevelopmentRegion" => "en" "CFBundleDisplayName" => "localWebServerExtension" "CFBundleExecutable" => "localWebServer" "CFBundleIdentifier" => "AsheKube.app.a-Shell.localWebServerExtension" "CFBundleInfoDictionaryVersion" => "6.0" "CFBundleName" => "localWebServer" "CFBundlePackageType" => "XPC!" "CFBundleShortVersionString" => "1.0" "CFBundleSupportedPlatforms" => [ 0 => "iPhoneOS" ] "CFBundleVersion" => "1" "DTCompiler" => "com.apple.compilers.llvm.clang.1_0" "DTPlatformBuild" => "23A339" "DTPlatformName" => "iphoneos" "DTPlatformVersion" => "26.0" "DTSDKBuild" => "23A339" "DTSDKName" => "iphoneos26.0" "DTXcode" => "2601" "DTXcodeBuild" => "17A400" "EXAppExtensionAttributes" => { "EXExtensionPointIdentifier" => "AsheKube.app.a-Shell.localWebServer" } "MinimumOSVersion" => "26.0" "NSHumanReadableCopyright" => "Copyright © 2025 AsheKube. All rights reserved." "UIDeviceFamily" => [ 0 => 1 1 => 2 ] "UIRequiredDeviceCapabilities" => [ 0 => "arm64" ] } What should I do to be able to upload on the AppStore?

I am developing an iOS/iPadOS application and have encountered some behavior regarding Files App and security-scoped bookmarks that I would like to clarify. Additionally, I would like to report some behavior which might include a potential issue. Question1: Accessing deleted files via bookmark (Specification clarification) Our app saves file URLs as bookmarks, which file that user has selected on Files App or app-created so to open a file which user has modified previously in the next launch. When a user deletes a file in Files App (moves a file to Recently Deleted), the app can still resolve the bookmark and access the file for read/write operations. Is this behavior intended? In other words, is it correct that a bookmark can access a file that has been deleted in Files App but not permanently removed? Question2: Overwriting a file in Recently Deleted (Potential bug) We noticed that overwriting a file in Recently Deleted behaves differently depending on the method used. Current implementation 1.Create a temporary file in the same directory 2.Write content to the temporary file 3.Delete the original file ([NSFileManager removeItemAtURL:error:]) 4.Move the temporary file to the original file path ([NSFileManager moveItemAtURL:toURL:error:]) Result: The file disappears from Files App Recently Deleted. In contrast, using [NSFileManager replaceItemAtURL:withItemAtURL:] keeps the file visible in Recently Deleted. Is this difference designed behavior? If not, this may be a bug. Question3: Detecting files in Recently Deleted We want to detect whether a file resides in Recently Deleted, but we cannot find a reliable and officially supported method. Recently Deleted files appear under .Trash, but using the path alone is not a reliable method. We have tried the following APIs without success: [NSURL getResourceValue:forKey:NSURLIsHiddenKey error:] [NSURL checkResourceIsReachableAndReturnError:] [NSFileManager fileExistsAtPath:] [NSFileManager isReadableFileAtPath:] [NSFileManager getRelationship:ofDirectory:NSTrashDirectory inDomain:NSUserDomainMask toItemAtURL:error:] We could not obtain the Recently Deleted folder URL using standard APIs. [NSFileManager URLsForDirectory:NSTrashDirectory inDomains:NSUserDomainMask] [NSFileManager URLForDirectory:NSTrashDirectory inDomain:NSUserDomainMask appropriateForURL:url create:error:] Could you advise a safe and supported way to detect Recently Deleted files properly by the app?

Environment: Xcode 26 iOS 26 Also tested on iOS 18 (working correctly) Description: I'm experiencing a behavior change with URL(fileURLWithPath:) when the filename starts with a tilde (~) character. On iOS 18, passing a filename like ~MyFile.txt to URL(fileURLWithPath:) treats the tilde as a literal character. However, on iOS 26, the same code resolves the tilde as the home directory, resulting in unexpected output. Minimal Example: let filename = "~MyFile.txt" let url = URL(fileURLWithPath: filename) print(url.lastPathComponent) Expected Result (iOS 18): ~MyFile.txt Actual Result (iOS 26): 924AF0C4-C3CD-417A-9D5F-733FBB8FCF29 The tilde is being resolved to the app's container directory, and lastPathComponent returns the container UUID instead of the filename. Questions: 1. Is this an intentional behavior change in iOS 26? 2. Is there documentation about this change? 3. What is the recommended approach for extracting filename components when the filename may contain special characters like ~? Workaround: Using NSString.lastPathComponent works correctly on both iOS versions: let filename = "~MyFile.txt" let result = (filename as NSString).lastPathComponent // Returns: "~MyFile.txt" ✅ Is this the recommended approach going forward?

The man page of copyfile sates the following: COPYFILE_CLONE [..] Note also that there is no support for cloning directories" COPYFILE_CLONE_FORCE [...] Note also that there is no support for cloning directories: if a directory is provided as the source, an error will be returned. Now the man page for clonefile: > Cloning directories with these functions is strongly discouraged. Use copyfile(3) to clone directories instead. -- So am I to enumerate the content of a directory build subfolders along the way in the target destination and clone each file inside individually? If I recall NSFileManager seems to clone a large directory instantly (edit actually I remembered wrong NSFileManager does not do this. Finder seems to copy instead of clone as well). On further inspection, clonefile states that it can do this, but it is discouraged. Interesting. I wonder why. If src names a directory, the directory hierarchy is cloned as if each item was cloned individually. However, the use of clonefile(2) to clone directory hierarchies is strongly discouraged. Use copyfile(3) instead for copying directories. P.S. - Forgive me if I posting this in the wrong category, I couldn't find a "category" in the list of available categories on these forums that seems appropriate for this question.

Greetings, I would like to understand this URLCache behavior for two different requests to the same end point but with a different header value. Here is a code with comment explaining the behavior. // Create a request to for a url. let url = URL(string: "https://&lt;my url&gt;?f=json")! var request = URLRequest(url: url) // Set custom header with a value. request.setValue("myvalue", forHTTPHeaderField: "CustomField") // Send request to get the response. let (data, response) = try await URLSession.shared.data(for: request) print("data: \(String(describing: String(data: data, encoding: .utf8)))") print("response: \(response)") // Create second request to the same url but with different value of custom header field. var request2 = URLRequest(url: url) request2.setValue("newvalue", forHTTPHeaderField: "CustomField") // Check the URL cache for second request and it returns the response // of the first request even though the second request has different header value. let cachedResponse = URLCache.shared.cachedResponse(for: request2) print("cachedResponse: \(cachedResponse?.response)") Is this a bug in URLCache that request headers are not matched while returning the response? Is this an expected behavior? If yes, why?

For ages, we've been using appStoreReceiptUrl to detect if the app was installed from TestFlight or not, but now that's deprecated. Since we have a strict policy of no warnings on the project, we need to find a way to check if the app was installed from TestFlight or from the App Store. Does anyone know what's the new way to do so? I thought about using MarketplaceKit.AppDistributor.testFlight but to use MarketplaceKit you need to jump through hoops that our app really doesn't need to - we don't distribute outside of the App Store. Any ideas are much appreciated! 🙏

Hello, I have a question about data deserialization using NSKeyedUnarchiver in iOS SDK development. Current Situation: Previously, we were using the NSKeyedUnarchiver.unarchiveObject(with: Data) function We have changed to using the NSKeyedUnarchiver.unarchivedObject(ofClasses:from:) method to deserialize complex objects stored in UserDefaults We need to include all types in the ofClasses parameter, including Swift primitive types as well as various custom classes and structs within the project Questions: Implementation Approach: Is it correct pattern to include all classes defined in the project in the ofClasses array? Is this approach recommended? Runtime Stability: When using this approach, is there a possibility of runtime crashes? Are there any performance issues? Alternative Methods: If the current approach is not the correct pattern, what alternatives should we consider? Current Code Structure: All model classes conform to the NSSecureCoding protocol We use the requiringSecureCoding: true parameter We use a whitelist approach, explicitly listing only allowed classes I would like to know if this structure is appropriate, or if we should consider a different approach. Thank you.

Hi, We can easily get drive throughput using the iostat command, but it only outputs plain text that needs to be parsed, and I’m not sure if the format or column order is consistent across macOS versions. Is there any API that provides the same disk I/O metrics that iostat reports, but in a way that can be safely called from a notarized app?

After switching our iOS app project from Swift 5 to Swift 6 and publishing an update, we started seeing a large number of crashes in Firebase Crashlytics. The crashes are triggered by NotificationCenter methods (post, addObserver, removeObserver) and show the following error: BUG IN CLIENT OF LIBDISPATCH: Assertion failed: Block was expected to execute on queue [com.apple.main-thread (0x1f9dc1580)] All scopes to related calls are already explicitly marked with @MainActor. This issue never occurred with Swift 5, but appeared immediately after moving to Swift 6. Has anyone else encountered this problem? Is there a known solution or workaround? Thanks in advance!

For bookmark creation and resolving, there's a NSURLBookmark{Creation,Resolution}MinimalBookmark enum value. What does this value imply on macOS and iOS? Specifically, to create security scoped bookmarks on macOS, we use NSURLBookmarkResolutionWithSecurityScope, but that is not available on iOS. Are iOS bookmarks always security scoped? Does the minimal enum imply security scoped bookmarks? Is 0 a valid value to bookmarkDataWithOptions, and does that give an even less scoped bookmark than NSURLBookmarkCreationMinimalBookmark`? We are also using NSURLBookmarkCreationWithoutImplicitSecurityScope on both iOS and macOS, to avoid any implicit resolution of bookmarks we resolve, so that we can explicitly control access by explicit calls to start/stopAccessing. How does NSURLBookmarkCreationWithoutImplicitSecurityScope relate to the enum values discussed above? Thanks! (https://mothersruin.com/software/Archaeology/reverse/bookmarks.html provides some really interesting insights, but doesn't discuss the minimal bookmarks.)

There are many units which are inverse of standard units, e.g. wave period vs Hz, pace vs speed, Siemens vs Ohms, ... Dimension can be subclassed to create the custom units. How to extend Measurement.converted( to: )? I was looking at somehow using UnitConverter and subclass to something like UnitConverterInverse. Thoughts?

I decode an object with NSKeyedArchiver (SecureCoding): typealias BoolArray = Array<Array<Bool>> let val = decoder.decodeObject(of: NSArray.self, forKey: someKey) as? BoolArray I get the following log: *** -[NSKeyedUnarchiver validateAllowedClass:forKey:] allowed unarchiving safe plist type ''NSNumber' (0x204cdbeb8) [/System/Library/Frameworks/Foundation.framework]' for key 'NS.objects', even though it was not explicitly included in the client allowed classes set: '{( "'NSArray' (0x204cd5598) [/System/Library/Frameworks/CoreFoundation.framework]" )}'. This will be disallowed in the future. I changed by adding NSNumber.self in the list : let val = decoder.decodeObject(of: [NSArray.self, NSNumber.self], forKey: someKey) as? BoolArray No more warning in log. Is there a reason for this ?

macOS 26 "Tahoe" is allocating much more memory for apps than former macOS versions: A customer contacted me with my app's Thumbnail extension allocating so much memory that her 48 GB RAM Mac Mini ran into "out of application memory" state. I couldn't identify any memory leak in my extension's code nor reproduce the issue, but found the main app allocating as much as 5 times the memory compared to running on macOS 15 or lower. This productive app is explicitly using "Liquid Glass" views as well as implicitly e.g. for an inspector pane. So I created a sample app, just based on Xcode's template of a document-based app, and the issue is still showing (although less dramatically): This sample app allocates 22 MB according to Tahoe's Activity Monitor, while Sequoia only requires 16 MB: macOS 15.6.1 macOS 26.2 Is anyone experiencing similar issues? I suspect some massive leak in Tahoe's memory management, and just filed a corresponding feedback (FB21967167).