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 TCP and UDP ports used by Apple software products support article 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. WWDC 2025 Session 250 Use structured concurrency with Network framework — This is a great introduction to the new Network framework API introduced in appleOS 2026. 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 Building peer-to-peer apps sample code 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. WWDC 2025 Session 314 Get ahead with quantum-secure cryptography 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. Prepare your network environment for stricter security requirements support article — This is primarily of interest to folks developing management software, for example, an MDM server. 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 just a learning

Security concern: To provide a visually appealing transition when launching or leaving an application, iOS introduced a feature that automatically captures a screenshot of the current view when an app is moved to the background. This screenshot is subsequently displayed as a preview in the App Switcher. There is security concern that the app shows sensitive information like activation codes or chat histories in the preview image of the App Switcher Need clarification on the following points: 1.Where exactly are these App Switcher preview screenshots stored on the device filesystem? 2.Can these App Switcher snapshots be accessed on a jailbroken iOS device? 3.Are these snapshots stored inside the application container or in a system-managed location outside the app sandbox? Can any Third party application or tool can access this screenshots in iOS device? 5.Is there any Apple-recommended API, entitlement, or platform-supported mechanism on iOS to prevent screenshots in iOS

Title: Does identifierForVendor (IDFV) change after transferring an app to another Apple Developer account? We are planning to transfer an existing App Store app from one Apple Developer account/team to another using App Transfer. The app currently uses: UIDevice.current.identifierForVendor as one of the identifiers sent to our backend. We would like to confirm the exact behavior of identifierForVendor after the app is transferred to the recipient developer account. Our scenario is: The app is currently published under Developer Team A. Existing users already have the app installed on their devices. We transfer the app to Developer Team B through App Store Connect. Developer Team B creates new certificates/provisioning profiles and publishes a new version of the same app. Existing users update the app normally from the App Store, without uninstalling it. Questions: After an existing user updates from the last version published by Team A to the first version published by Team B, will UIDevice.current.identifierForVendor remain the same, or will it be regenerated? Is the vendor used to calculate IDFV associated with: the App Store app record, the Bundle ID, the Team ID, the App ID Prefix, the developer organization/vendor, or some other value? Does App Transfer itself cause IDFV to change, or does the value only change under specific conditions such as changing the organization name or uninstalling all apps from the same vendor? If IDFV changes after App Transfer, does Apple provide any official migration or mapping mechanism that allows the backend to associate the old IDFV with the new IDFV? For example, Sign in with Apple provides a user migration mechanism when transferring an app between developer teams. Is there any equivalent mechanism for identifierForVendor? Is there any difference between: users who update the app directly after the transfer, and users who uninstall the old version and reinstall the app after the transfer? We have reviewed the documentation for identifierForVendor and App Transfer, but we could not find an explicit statement describing the IDFV behavior specifically for an App Transfer between two different developer teams. Our main concern is maintaining backend device associations for existing users after the transfer. We would appreciate an official clarification on whether IDFV continuity is guaranteed across App Transfer, and if not, what migration strategy Apple recommends.

I'm a font developer. In the development process, I will revise a font and overwrite the OTF file that is currently enabled (registered) with macOS. If I then launch an app, it will immediately use the revised version of the font; while apps that are already loaded will continue to use the old version. This suggests that each app is loading new and separate font data, rather than getting it from some existing cache in memory. Yet macOS does have a "font cache" of some sort. Some apps, like TextEdit, seem to only load the fonts that they need to use. However, other apps, like Pages, load every enabled (registered) font on the OS!! (According to the Open Files list in Activity Monitor.) Given that /System/Library/Fonts/ is 625 Mb, and we can't disable any of it, isn't that a lot of data to be repeating? How many fonts is too many fonts? I can't find much documentation about the process.

Hello When compiling a project containing localised file strings for dictionaries with the new release Xcode version 27, I receive an error as the compiler expect a plist instead of the string! validation failed: Couldn't parse property list because the input data was in an invalid format The Xcode version 26… did work fine I did file a Feedback Assistant FB24806196 Using a MacBook Air Apple silicon

I'm testing code that uses NSMetadataQuery and I noticed some odd behavior. I run a query where the search scope is set to my Desktop directory. The predicate is set to search for a file name that contains 'we' (display name to be precise: kMDItemDisplayName). And I get no results. So I stop the app from Xcode then I create a new folder on the Desktop and name it we exactly. Then I rerun my app and start the query again - still no results. Unfortunately none of the Spotlight based APIs I'm using report errors. There is no delegate method -queryDidFailWithError: or anything like that. So in another place my app uses the lower level MD prefixed APIs in Core Services to read file metadata and I notice that those APIs are failing as well. Specifically I try to load metadata for a PNG image. I create an MDItemRef via MDItemCreateWithURL (and I do get an MDItemRef). Then I call MDItemCopyAttributes with the MDItemRef and an array of metadata attribute names: CFDictionaryRef fetchedData = MDItemCopyAttributes(mdItem, attributeNames); I step through it in the debugger and fetchedData is NULL. Since there is no error handling APIs available for any of this my app just silently fails. I have Console.app open when I step through MDItemCopyAttributes call in the debugger and this logs out every time: com.apple.spotlightserver Bad checksum on fetch attributes reply from store, 0x123ea456.... FWIW I do not have Spotlight indexing turned off on my system. Also jumping to Finder I'm experiencing the same failures (metadata isn't populating and the Desktop search for we produces no results). Actually on further inspection it looks like all searches are producing no results. Spotlight appears to be in a broken state system wide. I'm pretty sure a system restart will 'fix' it - until it starts occurring again. But for obvious reasons I'd like to avoid releasing a feature in my app that results in this kind of experience. Is there anything I can do on my end to workaround or avoid this issue? And tips or advice would be greatly appreciated.

Hi, I’m developing a native macOS music app intended for the Mac App Store. We already support Audio Units and are investigating VST3 instrument and effect hosting on Apple Silicon. Users would install plugins themselves, typically in: /Library/Audio/Plug-Ins/VST3 ~/Library/Audio/Plug-Ins/VST3 The app would load these third-party plugin bundles using public APIs, such as CFBundleLoadExecutableAndReturnError. Plugins may be signed by developers with different Team IDs. Our app would not download or install them. Is there a supported way to load and execute these bundles while the hosting process remains sandboxed throughout? If so, which APIs and entitlements should we use? Specifically, I’m trying to distinguish permission to read a plugin bundle from permission to load its executable code. Would user selected folder access and security scoped bookmarks cover the sandbox access requirements, or is another mechanism needed? I understand that com.apple.security.cs.disable-library-validation addresses loading code signed by other developers, but does not itself grant sandbox file access. We cannot rely on an Audio Unit compatibility exception that disables the host’s sandbox. App Review Guideline 3.1.1 (https://developer.apple.com/app-store/review/guidelines/#in-app-purchase) explicitly allows Mac App Store apps to host plugins enabled outside the App Store. I’m looking for the supported technical approach under App Sandbox, rather than preapproval for our app. We’re checking this before implementation, so we don’t yet have a failing reproducer. Any relevant documentation, sample code or existing discussion would be appreciated. Thanks, Ben

If the user prohibits Spotlight in System Settings for a given directory and I set that URL as one of the search scopes on an NSMetadataQuery- I believe the query will return no results. Is there an API for detecting Spotlight unavailability? Ideally I would like to display something in the UI for this kind of situation to explain why a feature built on top of this API is not working.

We are seeing a hard main-thread abort on iOS 26 during cold launch when VoiceOver (or another accessibility client) is active. about 1–7 seconds after process start. The crashing thread essentially shows only main from the app; the fatal path is entirely in system frameworks. What happens is that UIAccessibility asks for an accessibility value, UIKit.axbundle handles it (on iOS 26.5 we exact-match-symbolicate this to -[_UITabButtonAccessibility accessibilityValue] + 120), then AXCoreUtilities safeSwiftValueForKey reflects a Swift object via Mirror / AttributeGraph. While copying an unowned field, the referent is already gone, so libswiftCore calls swift_abortRetainUnowned and the process dies. Not finding unowned in app source does not contradict this: the reflected object can live in system or SDK Swift state. OS versions in the corpus: iOS 26.5 (23F77), 26.6 (23G71), and 26.6.1 (23G83). All reports load UIKit.axbundle. Launch-to-crash gaps range from roughly 1.4s to 7.3s. Most 26.6 samples share UIKit.axbundle binary UUID 387c6473…; we did not have matching Device Support for that build locally. One iOS 26.5 sample has UIKit.axbundle binary UUID dca69975… and AXCoreUtilities 78a7c163…, both exactly matching local Device Support, so atos on that sample is trustworthy. On that iOS 26.5 sample (filename redacted), the symbolicated path is: VoiceOver / AX → UIAccessibility (_iosAccessibilityAttributeValue → _accessibilityAXAttributedValue → _accessibilityPotentiallyAttributedValueForNonAttributedSelector) → UIKit.axbundle -[_UITabButtonAccessibility accessibilityValue] + 120 → AXCoreUtilities (_AXSafeSwiftValueForKeyTm → safeSwiftValueForKey → _visitValueWithReflection) → AttributeGraph (AGTypeApplyFields2::Visitor::visit_field) → libswiftCore (swift_reflectionMirror_subscript → copyUnownedFieldContents → swift_unknownObjectUnownedLoadStrong → swift_abortRetainUnowned) → App: main only Frame 32 math: runtime 0x2be49b130, slide base 0x2be3cf000, offset 0xCC130 → _UITabButtonAccessibility accessibilityValue + 120. Questions for anyone hitting the same stack: 1.Is there already an Apple Feedback / radar for safeSwiftValueForKey + swift_abortRetainUnowned on iOS 26? crash_ios265_redacted.txt

Does anybody know if Apple allows for apps to access a user’s applicationa’ usage data? As a part of an app idea I have I need to see What is the screen time of each user on each app (Not only mine). Is it possible?

Hi, My Mac app allows a customer to drag and drop a file package onto a SwiftUI view. I can't seem to find a way to successfully call .startAccessingSecurityScopedResource() with the file/dir that was dropped into the view. I put together a simple test app. Here is the code: struct ContentView: View { @State var isTargetedForDrop: Bool = false var body: some View { VStack { Image(systemName: "globe") .imageScale(.large) .foregroundStyle(.tint) Text("Hello, world!") Rectangle() .stroke(Color.gray) .onDrop(of: [UTType.fileURL], isTargeted: $isTargetedForDrop) { providers in guard let provider = providers.first(where: { $0.hasItemConformingToTypeIdentifier(UTType.fileURL.identifier) }) else { return false } provider.loadItem(forTypeIdentifier: UTType.fileURL.identifier, options: nil) { item, error in if let error = error { print("Drop load error: \(error)") return } if let url = item as? URL { print("Dropped file URL: \(url)") } else if let data = item as? Data, let url = URL(dataRepresentation: data, relativeTo: nil) { print("Dropped file URL (from data): \(url)") let access = url.startAccessingSecurityScopedResource() if access { print("Successfully accessed file at URL: \(url)") } else { print("Failed to access file at URL: \(url)") } url.stopAccessingSecurityScopedResource() } else { print("Unsupported dropped item: \(String(describing: item))") } } return true } } .padding() } } When I drop a file package into this view I see, "Failed to access file at URL: <the_full_file_path>" I'm running Xcode 26 on macOS 26.

We maintain a large file-sync app. After our upload endpoint moved to HTTP/2, we found that when multiple NSURLSessionUploadTasks run concurrently, all tasks send their request headers immediately (multiplexed on a single connection — confirmed identical localPort via URLSessionTaskMetrics), but request bodies are transmitted essentially one task at a time: while one task's body saturates the uplink, the other tasks send zero body bytes for the entire duration (countOfBytesSent == 0). This reproduces with both background sessions (BackgroundUploadTask) and default sessions (LocalUploadTask), on Wi-Fi and cellular. iOS 26.5, Xcode 26.3, tasks created with uploadTask(with:fromFile:), multipart POST. This becomes a hard failure behind a load balancer with slow-POST (RUDY) protection: requests whose first body KB doesn't arrive within 5s are rejected with 408. The starved tasks fail even though the network is healthy. For comparison, OkHttp on Android writes bodies in interleaved 16KB DATA frames under identical conditions, so all streams pass the first-KB check. Metrics excerpt (4 concurrent uploads, one h2 connection): task 1: duration 18.7s, sent 180MB (full line rate) task 2: duration 22.8s, sent 43MB (transmitted only after task 1 finished) task 3: duration 46.0s, sent 247MB (after task 2) task 4: duration 5.2s, sent 0 bytes → 408 from the gateway In one run a starved stream sent exactly 65,536 bytes (the default initial stream window) and then stalled. Questions: Is this sender-side scheduling (no round-robin between streams' DATA frames) the expected CFNetwork behavior? Does URLSessionTask.priority influence HTTP/2 stream weighting for upload bodies? Is there any other way to influence bandwidth sharing between concurrent uploads? Is there any supported way to opt out of HTTP/2 (constrain ALPN to HTTP/1.1) or cap concurrent streams per connection from the client side? We believe there isn't, but would like to confirm. What is the recommended pattern for concurrent large uploads in this situation? Filed as FB24062619 with full sanitized metrics attached. Happy to provide more data.

In my apps, I have a requirement to display an image of the application icon is certain circumstances. This is fairly straightforward for iOS/iPadOS and it used to be straightforward for macCatalyst. For MacCatalyst, this is no longer true (at least since macOS 26). This is because the app icon is now stored as an .icns file and (in the case of using an IconComposer icon), the `'png' in the Asset Catalog now has an unknown name. So the following code no longer works: public extension Bundle { var icon: UIImage? { #if targetEnvironment(macCatalyst) guard let iconName = infoDictionary?["CFBundleIconName"] as? String else { return nil } return UIImage(named: iconName, in: self, compatibleWith: nil) #else guard let icons = infoDictionary?["CFBundleIcons"] as? [String : Any] else { return nil } guard let primaryIcon = icons["CFBundlePrimaryIcon"] as? [String : Any] else { return nil } guard let iconFiles = primaryIcon["CFBundleIconFiles"] as? [String] else { return nil } guard let file = iconFiles.last else { return nil } return UIImage(named: file, in: self, compatibleWith: nil) #endif } The obvious solution is to place an Image in the Asset Catalog which I can access, but this is a maintenance headache. What I would actually like to do is either create a UIImage directly from the .icns file, or access the .png file in the Asset Catalog (which has a name beginning with the icon file name, but has additional characters in its name that I don't know). Can you help?

Question 1 (Return journey from containing app back to original host): Is there an alternative, supported method for a custom keyboard extension to launch its containing app such that when that containing app is later suspended/resigned, the system returns the user to the original host app (e.g., Notes) instead of the Home screen? Does iOS 26 provide any handoff/return APIs for the keyboard voice‑input scenario? Question 2 (Full‑access‑off persistence and settings navigation): (a) Is the shared app group container expected to be effectively read‑only (with EPERM) when Full Access is off? If so, is there any supported way to persist keyboard settings (that require writing to shared files) without Full Access? (b) What is the supported method for a keyboard extension to direct the user to Settings to enable Full Access on iOS 26, given that openURL via responder chain and extensionContext.open both fail? We are seeking a reliable, non‑private API approach.

UserDefaults store app-related settings, and I am just worried that if an SDK also writes to the UserDefaults, that there could be potentially some key collisions between the host app and the SDK. Is the concern just in my head or does it have merit?

Overview I would like to observe calendar changes using NotificationCenter.messages(of: for:) I want receive Sendable messages, not traditional Notification which is not Sendable Problem I can't seem to get the following code to compile import EventKit NotificationCenter.default.messages( of: EKEventStore.EventStoreChanged.Subject.self, for: .changed ) Reference https://developer.apple.com/documentation/foundation/notificationcenter/messageidentifier/changed-50yz5 Questions How can I use by using NotificationCenter.messages(of: for:) for Calendar changes?

macOS 27.0 beta 4 I have an installer app which needs to set a key/value inside a plist file during installation. This is for a screensaver that runs under the legacyScreensaver system, so the plist lives at: ~/Library/Containers/com.apple.ScreenSaver.Engine.legacyScreenSaver.x86-64/Data/Library/Preferences/com.foobar.plist Although I can see the plist file in the Finder, my installer app can't read or write it, and the NSAppDataUsageDescription string is not shown, nor does the OS ask the user for permission. Also, trying to do this via the Terminal app is also blocked (even using 'sudo'). I understand this is part of the new Golden Gate security system. In Golden Gate, is there a legitimate way to accomplish this so it works like it did in macOS 26 and earlier? I'd like my installer to request access, the NSAppDataUsageDescription string is shown, and the user can grant or deny permission.

userlog.txt We've run into some HTTP request errors, details as follows: We're currently at a loss because restarting the app doesn't help, only rebooting the phone restores things to normal. Based on tracking data, the occurrence rate for users is about 0.033%, and it's only happening on iOS, Android is fine. iOS operating system versions: 14-27 are all affected. The same issue appears in Rust, Flutter, and C/C++. Rust： 2026-07-11-19:39:22.252+0800|F4E26069-2D7E-4D5F-8B53-664E012B2CA7|UPLogDefaultLogger|DEBUG|测试模式|1023629905|[userdomain_rust/rust_userdomain/src/operator/device_ops/refresh_device_list_op.rs:61]query_device_list error: HttpRequstFaild(Reqwest(reqwest::Error { kind: Request, url: "https://zj.haier.net/api-gw/wisdomdevice/device/v11/family/devices?familyId=ALL&filterFlag=false", source: hyper_util::client::legacy::Error(Connect, ConnectError("tcp connect error", 36.156.179.34:443, Os { code: 49, kind: AddrNotAvailable, message: "Can't assign requested address" })) })) Flutter： 2026-07-11-15:29:02.718371+0800|b2257ae8-f7d8-41d0-8811-2ff1824f95d9|UpPlugins|ERROR|正常模式|1023629905|level:error tag:smart_home msg:getWholeHousePreferenceSetting err: DioException [unknown]: null Error: SocketException: Connection failed (OS Error: Can't assign requested address, errno = 49), address = zj.haier.net, port = 443 C/C++： 2026-07-11-19:39:15.247588+0800|a991af96-bf02-4b94-a437-d4f7efc249ff|uSDK|ERROR|正常模式|1023629905|[CAE][[cae_sock_no_ssl_last_err:869][connect fd 122 ret -1 err 49: Can't assign requested address] ] Native iOS HTTP interface requests work fine, for example when using AFNetworking. Looking for your help~

Can anyone explain to me why my UI doesn't update after the timer fires in this code below? Even when the timer fires, the UI doesn't update. thanks, in advance for any guidance Mike struct ContentView: View { @State var referenceDate: Date = Date() init () { setupTimer() } func setupTimer() { let calendar = Calendar.current guard let triggerDate = calendar.nextDate( after: Date(), matching: DateComponents(hour: 14, minute: 46, second: 0), matchingPolicy: .nextTime ) else { return } let timer = Timer(fire: triggerDate, interval: 0.2, repeats: false) { _ in self.referenceDate = Date() print("runLoop!") } RunLoop.main.add(timer, forMode: .common) } var body: some View { VStack { Text("Ref time: \(referenceDate.formatted(date: .abbreviated, time: .standard))") } } }