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Explore the networking protocols and technologies used by the device to connect to Wi-Fi networks, Bluetooth devices, and cellular data services.

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URLSession.dataTask(with: URL) error: Type of expression is ambiguous without a type annotation
I'm a long-time developer, but pretty new to Swift. I'm trying to get information from a web service (and found code online that I adjusted to build the function below). (Note: AAA_Result -- referenced towards the end -- is another class in my project) Trouble is, I'm getting the subject error on the call to session.dataTask. Any help/suggestions/doc pointers will be greatly appreciated!!! var result: Bool = false var cancellable: AnyCancellable? self.name = name let params = "json={\"\"}}" // removed json details let base_url = URL(string: "https://aaa.yyy.com?params=\(params)&format=json")! // removed URL specifics do { let task = URLSession.shared.dataTask(with: base_url) { data, response, error in if let error = error { print("Error: \(error)") } guard let response = response as? HTTPURLResponse, (200...299).contains(response.statusCode) else { print("Error \(String(describing: response))") } do { let decoder = JSONDecoder() let ar = try decoder.decode(AAA_Result.self, from: response.value) // removed specific details... result = true } catch { print(error) } } task.resume() } catch { print(error) } return result }
4
0
116
May ’25
iOS 26 Crash: _xzm_xzone_malloc_freelist_outlined in com.apple.network.connections
Hello Apple Support Team, We are seeing a production crash on iOS 26 devices that appears to originate from Apple system frameworks rather than application code. Crash Summary Crash signature: _xzm_xzone_malloc_freelist_outlined Crashed thread: com.apple.network.connections Frameworks involved: CFNetwork, Security, libdispatch, libsystem_malloc Affected OS: iOS 26.x App built with: Xcode 16 Devices: Multiple models (not device-specific) Reproducibility: Intermittent, higher frequency during app launch / background networking Observed Stack Trace (top frames) _xzm_xzone_malloc_freelist_outlined dispatch_data_create_alloc xpc_data_deserialize SecTrustEvaluateIfNecessary CFNetwork HTTPProtocol / HTTP3Connection com.apple.network.connections App Context The app uses URLSession for networking. Multiple third-party SDKs are integrated (Firebase Analytics, Dynatrace, Appsflyer, and similar analytics/monitoring SDKs). These SDKs perform concurrent background network requests, especially during app launch and foreground transitions. No unsafe memory operations (manual malloc/free, unsafe pointers, or custom networking stacks) are used in the app code. Key Observations The crash is predominantly observed on iOS 26 and not on earlier iOS versions. Stack traces do not include application symbols. Disabling or delaying analytics SDK initialization significantly reduces the crash rate. Reducing concurrent network requests and limiting HTTP/3 usage also mitigates the issue. This suggests a potential regression in CFNetwork / Network.framework / HTTP/3 handling combined with the new memory allocator (xzone) on iOS 26. Impact Random app termination during background networking. Occurs without a clear deterministic repro path, making it difficult to fully mitigate at the app level. Request Could you please help investigate whether this is a known iOS 26 issue related to: HTTP/3 / QUIC networking XPC deserialization Memory allocation in the new xzone allocator High-concurrency network requests We would appreciate guidance on: Recommended mitigations Whether this issue is already tracked internally Any best practices for apps integrating multiple analytics SDKs on iOS 26 Crash logs and additional diagnostics can be provided if needed. Thank you for your support. Best regards, Dhananjay
0
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135
Feb ’26
WiFi aware demo paring issue
I am developing a program on my chip and attempting to establish a connection with the WiFi Aware demo app launched by iOS 26. Currently, I am encountering an issue during the pairing phase. If I am the subscriber of the service and successfully complete the follow-up frame exchange of pairing bootstrapping, I see the PIN code displayed by iOS. Question 1: How should I use this PIN code? Question 2: Subsequently, I need to negotiate keys with iOS through PASN. What should I use as the password for the PASN SAE process? If I am the subscriber of the service and successfully complete the follow-up frame exchange of pairing bootstrapping, I should display the PIN code. Question 3: How do I generate this PIN code? Question 4: Subsequently, I need to negotiate keys with iOS through PASN. What should I use as the password for the PASN SAE process?
1
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609
Nov ’25
VPN Stuck at connecting
Hello, I’ve run into some strange behavior with the macOS System Extension using a Packet Tunnel. The issue showed up after the device went to sleep while the VPN was running. When I woke the computer, the VPN tried to reconnect but never succeeded — it just stayed stuck in the “connecting” state. I was able to turn the VPN off, but every attempt to turn it back on failed and got stuck at “connecting” again. Even removing the VPN configuration from Settings didn’t help. The only thing that worked was disabling the system extension completely. While checking the logs, I noticed thousands of identical log messages appearing within just a few seconds: nesessionmanager(562) deny(1) system-fsctl (_IO "h" 47) 17:11:52.481498+0200 NESMVPNSession[Primary Tunnel:Secure DNS: got On Demand start message from pid 5454 com.apple.networkextension 17:11:52.481568+0200 NESMVPNSession[Primary Tunnel:Secure DNS: got On Demand start message from pid 5454 com.apple.networkextension 17:11:52.481580+0200 NESMVPNSession[Primary Tunnel:Secure DNS: got On Demand start message from pid 5454 com.apple.networkextension 17:11:52.481587+0200 NESMVPNSession[Primary Tunnel:Secure DNS: got On Demand start message from pid 5454 com.apple.networkextension 17:11:52.481646+0200 NESMVPNSession[Primary Tunnel:Secure DNS: got On Demand start message from pid 5446 com.apple.networkextension 17:11:52.481664+0200 NESMVPNSession[Primary Tunnel:Secure DNS: got On Demand start message from pid 5446 com.apple.networkextension 17:11:52.481671+0200 NESMVPNSession[Primary Tunnel:Secure DNS: got On Demand start message from pid 5446 com.apple.networkextension 17:11:52.481676+0200 NESMVPNSession[Primary Tunnel:Secure DNS: got On Demand start message from pid 5446 com.apple.networkextension 17:11:52.481682+0200 NESMVPNSession[Primary Tunnel:Secure DNS: got On Demand start message from pid 5446 com.apple.networkextension 17:11:52.481687+0200 NESMVPNSession[Primary Tunnel:Secure DNS: got On Demand start message from pid 5446 com.apple.networkextension After the burst of these repeated messages, I started seeing logs like the following: 17:11:52.481759+0200 NESMVPNSession[Primary Tunnel:Secure DNS: Received a start command from Spotify Helper[69038] com.apple.networkextension 17:11:52.481790+0200 NESMVPNSession[Primary Tunnel:Secure DNS: Skip a start command from Spotify Helper[69038]: session in state connecting com.apple.networkextension 17:11:52.481949+0200 NESMVPNSession[Primary Tunnel:Secure DNS: Received a start command from Spotify Helper[69038] com.apple.networkextension 17:11:52.481966+0200 NESMVPNSession[Primary Tunnel:Secure DNS: Skip a start command from Spotify Helper[69038]: session in state connecting com.apple.networkextension 17:11:52.481986+0200 NESMVPNSession[Primary Tunnel:Secure DNS: Received a start command from Spotify Helper[69038] com.apple.networkextension 17:11:52.481992+0200 NESMVPNSession[Primary Tunnel:Secure DNS: Skip a start command from Spotify Helper[69038]: session in state connecting com.apple.networkextension 17:11:52.482003+0200 NESMVPNSession[Primary Tunnel:Secure DNS: Received a start command from Spotify Helper[69038] com.apple.networkextension 17:11:52.482011+0200 NESMVPNSession[Primary Tunnel:Secure DNS: Skip a start command from Spotify Helper[69038]: session in state connecting com.apple.networkextension 17:11:52.482022+0200 NESMVPNSession[Primary Tunnel:Secure DNS: Received a start command from Spotify Helper[69038] com.apple.networkextension 17:11:52.482028+0200 NESMVPNSession[Primary Tunnel:Secure DNS: Skip a start command from Spotify Helper[69038]: session in state connecting com.apple.networkextension 17:11:52.482039+0200 NESMVPNSession[Primary Tunnel:Secure DNS: Received a start command from Spotify Helper[69038] com.apple.networkextension 17:11:52.482049+0200 NESMVPNSession[Primary Tunnel:Secure DNS: Skip a start command from Spotify Helper[69038]: session in state connecting com.apple.networkextension 17:11:52.482060+0200 NESMVPNSession[Primary Tunnel:Secure DNS: Received a start command from Slack Helper[84828] com.apple.networkextension 17:11:52.482069+0200 NESMVPNSession[Primary Tunnel:Secure DNS: Skip a start command from Slack Helper[84828]: session in state connecting com.apple.networkextension 17:11:52.482079+0200 NESMVPNSession[Primary Tunnel:Secure DNS: Received a start command from sharingd[764] com.apple.networkextension 17:11:52.482086+0200 NESMVPNSession[Primary Tunnel:Secure DNS: Skip a start command from sharingd[764]: session in state connecting com.apple.networkextension It is clear that the connection is in a loop of submitting request to start and then failing. This problem occured only after sleep on macOS 26.0 and 15.6. This issue only occured after the system woke up from sleep. macOS 15.6 and 26.0. Is this a known problem, and how should I go about troubleshooting or resolving it?
3
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165
Oct ’25
[iOS 26] Unable to start TLS handshake connection to devices with self-signed certificates
Hi there, We are facing some issues regarding TLS connectivity: Starting with iOS 26, the operating system refuses to open TLS sockets to local devices with self-signed certificates over Wi-Fi. In this situation, connection is no longer possible, even if the device is detected on the network with Bonjour. We have not found a workaround for this problem. We've tryied those solutions without success: Added the 'NSAppTransportSecurity' key to the info.plist file, testing all its items, such as "NSAllowsLocalNetworking", "NSExceptionDomains", etc. Various code changes to use properties such as "sec_protocol_options_set_local_identity" and "sec_protocol_options_set_tls_server_name" to no avail. Brutally import the certificate files into the project and load them via, for example, "Bundle.main.url(forResource: "nice_INTERFACE_server_cert", withExtension: "crt")", using methods such as sec_trust_copy_ref and SecCertificateCopyData. Download the .pem or .crt files to the iPhone, install them (now visible under "VPN & Device Management"), and then flag them as trusted by going to "Settings -> General -> Info -> Trust". certificates" The most critical part seems to be the line sec_protocol_options_set_verify_block(tlsOptions.securityProtocolOptions, { $2(true) }, queue) whose purpose is to bypass certificate checks and validate all of them (as apps already do). However, on iOS26, if I set a breakpoint on leg$2(true),` it never gets there, while on iOS 18, it does. I'll leave as example the part of the code that was tested the most below. Currently, on iOS26, the handler systematically falls back to .cancelled: func startConnection(host: String, port: UInt16) { self.queue = DispatchQueue(label: "socketQueue") let tlsOptions = NWProtocolTLS.Options() sec_protocol_options_set_verify_block(tlsOptions.securityProtocolOptions, { $2(true) }, queue) let parameters = NWParameters(tls: tlsOptions) self.nwConnection = NWConnection(host: .init(host), port: .init(rawValue: port)!, using: parameters) self.nwConnection.stateUpdateHandler = { [weak self] state in switch state { case .setup: break case .waiting(let error): self?.connectionDidFail(error: error) case .preparing: break case .ready: self?.didConnectSubject.onNext(Void()) case .failed(let error): self?.connectionDidFail(error: error) case .cancelled: self?.didDisconnectSubject.onNext(nil) @unknown default: break } } self.setupReceive() self.nwConnection.start(queue: queue) } These are the prints made during the procedure. The ones with the dot are from the app, while the ones without are warnings/info from Xcode: 🔵 INFO WifiNetworkManager.connect():52 - Try to connect onto the interface access point with ssid NiceProView4A9151_AP 🔵 INFO WifiNetworkManager.connect():68 - Connected to NiceProView4A9151_AP tcp_output [C13:2] flags=[R.] seq=215593821, ack=430284980, win=4096 state=CLOSED rcv_nxt=430284980, snd_una=215593821 nw_endpoint_flow_failed_with_error [C13 192.168.0.1:443 in_progress channel-flow (satisfied (Path is satisfied), viable, interface: en0[802.11], dns, uses wifi, LQM: unknown)] already failing, returning nw_connection_copy_protocol_metadata_internal_block_invoke [C13] Client called nw_connection_copy_protocol_metadata_internal on unconnected nw_connection nw_connection_copy_protocol_metadata_internal_block_invoke [C13] Client called nw_connection_copy_protocol_metadata_internal on unconnected nw_connection nw_connection_copy_connected_local_endpoint_block_invoke [C13] Client called nw_connection_copy_connected_local_endpoint on unconnected nw_connection nw_connection_copy_connected_remote_endpoint_block_invoke [C13] Client called nw_connection_copy_connected_remote_endpoint on unconnected nw_connection nw_connection_copy_protocol_metadata_internal_block_invoke [C14] Client called nw_connection_copy_protocol_metadata_internal on unconnected nw_connection nw_connection_copy_protocol_metadata_internal_block_invoke [C14] Client called nw_connection_copy_protocol_metadata_internal on unconnected nw_connection nw_connection_copy_connected_local_endpoint_block_invoke [C14] Client called nw_connection_copy_connected_local_endpoint on unconnected nw_connection nw_connection_copy_connected_remote_endpoint_block_invoke [C14] Client called nw_connection_copy_connected_remote_endpoint on unconnected nw_connection [C14 192.168.0.1:443 tcp, tls, attribution: developer] is already cancelled, ignoring cancel [C14 192.168.0.1:443 tcp, tls, attribution: developer] is already cancelled, ignoring cancel nw_connection_copy_protocol_metadata_internal_block_invoke [C15] Client called nw_connection_copy_protocol_metadata_internal on unconnected nw_connection nw_connection_copy_protocol_metadata_internal_block_invoke [C15] Client called nw_connection_copy_protocol_metadata_internal on unconnected nw_connection nw_connection_copy_connected_local_endpoint_block_invoke [C15] Client called nw_connection_copy_connected_local_endpoint on unconnected nw_connection nw_connection_copy_connected_remote_endpoint_block_invoke [C15] Client called nw_connection_copy_connected_remote_endpoint on unconnected nw_connection nw_connection_copy_protocol_metadata_internal_block_invoke [C16] Client called nw_connection_copy_protocol_metadata_internal on unconnected nw_connection nw_connection_copy_protocol_metadata_internal_block_invoke [C16] Client called nw_connection_copy_protocol_metadata_internal on unconnected nw_connection nw_connection_copy_connected_local_endpoint_block_invoke [C16] Client called nw_connection_copy_connected_local_endpoint on unconnected nw_connection nw_connection_copy_connected_remote_endpoint_block_invoke [C16] Client called nw_connection_copy_connected_remote_endpoint on unconnected nw_connection [C16 192.168.0.1:443 tcp, tls, attribution: developer] is already cancelled, ignoring cancel [C16 192.168.0.1:443 tcp, tls, attribution: developer] is already cancelled, ignoring cancel 🔴 ERROR InterfaceDisconnectedViewModel.connect():51 - Sequence timeout.
1
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270
Oct ’25
DNS duration 4294893875545978
When I use NSURLSessionTaskTransactionMetrics property domainLookupStartDate and domainLookupEndDate to calculate the duration of DNS, sometimes I get 4294893875545978 or -4294893875545978 return method like this [NSNumber numberWithLongLong:[taskMetrics.domainLookupEndDate timeIntervalSinceDate:taskMetrics.domainLookupStartDate?]*1000000000] The hexadecimal value of 4294893875545978 is 0xF3F3F3F3F3F3A. Is 4294893875545978 a special value?
3
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82
Mar ’25
NFC Missing required entitlement
Hi, I have created an application for NFC tag scanning and read the tag data. For that, i enabled the capability: NearField Communication Tag reading. Then I added 2 tag formats in the entitlement then i added info.plist: NFCReaderUsageDescription We need to use NFC com.apple.developer.nfc.readersession.felica.systemcodes 8005 8008 0003 fe00 90b7 927a 12FC 86a7 com.apple.developer.nfc.readersession.iso7816.select-identifiers D2760000850100 D2760000850101 but even though when i run the app and tap the nfc card im getting some error: NFCTag didBecomeActive 2025-08-29 19:08:12.272278+0530 SAFRAN_NFC[894:113090] NFCTag didDetectTags 2025-08-29 19:08:12.282869+0530 SAFRAN_NFC[894:113520] [CoreNFC] -[NFCTagReaderSession _connectTag:error:]:730 Error Domain=NFCError Code=2 "Missing required entitlement" UserInfo={NSLocalizedDescription=Missing required entitlement} 2025-08-29 19:08:12.284044+0530 SAFRAN_NFC[894:113090] NFCTag restarting polling 2025-08-29 19:08:12.372116+0530 SAFRAN_NFC[894:113090] NFCTag didDetectTags 2025-08-29 19:08:12.381535+0530 SAFRAN_NFC[894:113378] [CoreNFC] -[NFCTagReaderSession _connectTag:error:]:730 Error Domain=NFCError Code=2 "Missing required entitlement" UserInfo={NSLocalizedDescription=Missing required entitlement} 2025-08-29 19:08:12.382246+0530 SAFRAN_NFC[894:113090] NFCTag restarting polling 2025-08-29 19:08:12.470667+0530 SAFRAN_NFC[894:113090] NFCTag didDetectTags 2025-08-29 19:08:12.479336+0530 SAFRAN_NFC[894:113378] [CoreNFC] -[NFCTagReaderSession _connectTag:error:]:730 Error Domain=NFCError Code=2 "Missing required entitlement" UserInfo={NSLocalizedDescription=Missing required entitlement} 2025-08-29 19:08:12.480101+0530 SAFRAN_NFC[894:113090] NFCTag restarting polling Could you please help me wha tis the issue and give solution for that?
1
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214
Aug ’25
DMG Distribution for macOS App with App Extension — Should I Use System Extension Instead?
Hi everyone, I’m currently developing a macOS app that is distributed via a DMG file on our website. The app includes an App Extension (appex) for Network Extension functionality. I’m wondering if distributing via DMG on the web requires the app extension to be implemented as a System Extension instead of an App Extension. Is it necessary to migrate to System Extension for web-based DMG distribution, or can I continue using App Extension as is? Any insights or recommendations would be greatly appreciated. Thank you!
1
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65
Aug ’25
“Wi-Fi Aware Sample” on Phone quit unexpectedly.
The app “Wi-Fi Aware Sample” on Bojie的iPhone quit unexpectedly. Domain: IDEDebugSessionErrorDomain Code: 20 Failure Reason: Message from debugger: The LLDB RPC server has crashed. You may need to manually terminate your process. The crash log is located in ~/Library/Logs/DiagnosticReports and has a prefix 'lldb-rpc-server'. Please file a bug and attach the most recent crash log. User Info: { DVTErrorCreationDateKey = "2025-09-17 10:26:56 +0000"; IDEDebugSessionErrorUserInfoUnavailabilityError = "Error Domain=com.apple.dt.deviceprep Code=-10 "Fetching debug symbols for Bojie\U7684iPhone" UserInfo={NSLocalizedRecoverySuggestion=Xcode will continue when the operation completes., NSLocalizedDescription=Fetching debug symbols for Bojie\U7684iPhone}"; IDERunOperationFailingWorker = DBGLLDBLauncher; } Event Metadata: com.apple.dt.IDERunOperationWorkerFinished : { "device_identifier" = "00008101-001E29E01E63003A"; "device_isCoreDevice" = 1; "device_model" = "iPhone13,3"; "device_osBuild" = "26.0 (23A341)"; "device_osBuild_monotonic" = 2300034100; "device_os_variant" = 1; "device_platform" = "com.apple.platform.iphoneos"; "device_platform_family" = 2; "device_reality" = 1; "device_thinningType" = "iPhone13,3"; "device_transport" = 1; "dvt_coredevice_version" = "477.23"; "dvt_coredevice_version_monotonic" = 477023000000000; "dvt_coresimulator_version" = 1043; "dvt_coresimulator_version_monotonic" = 1043000000000000; "dvt_mobiledevice_version" = "1818.0.1"; "dvt_mobiledevice_version_monotonic" = 1818000001000000; "launchSession_schemeCommand" = Run; "launchSession_schemeCommand_enum" = 1; "launchSession_targetArch" = arm64; "launchSession_targetArch_enum" = 6; "operation_duration_ms" = 1922640; "operation_errorCode" = 20; "operation_errorDomain" = IDEDebugSessionErrorDomain; "operation_errorWorker" = DBGLLDBLauncher; "operation_error_reportable" = 1; "operation_name" = IDERunOperationWorkerGroup; "operation_unavailabilityErrorCode" = "-10"; "operation_unavailabilityErrorDomain" = "com.apple.dt.deviceprep"; "param_consoleMode" = 1; "param_debugger_attachToExtensions" = 0; "param_debugger_attachToXPC" = 1; "param_debugger_type" = 3; "param_destination_isProxy" = 0; "param_destination_platform" = "com.apple.platform.iphoneos"; "param_diag_MainThreadChecker_stopOnIssue" = 0; "param_diag_MallocStackLogging_enableDuringAttach" = 0; "param_diag_MallocStackLogging_enableForXPC" = 1; "param_diag_allowLocationSimulation" = 1; "param_diag_checker_mtc_enable" = 1; "param_diag_checker_tpc_enable" = 1; "param_diag_gpu_frameCapture_enable" = 0; "param_diag_gpu_shaderValidation_enable" = 0; "param_diag_gpu_validation_enable" = 0; "param_diag_guardMalloc_enable" = 0; "param_diag_memoryGraphOnResourceException" = 0; "param_diag_queueDebugging_enable" = 1; "param_diag_runtimeProfile_generate" = 0; "param_diag_sanitizer_asan_enable" = 0; "param_diag_sanitizer_tsan_enable" = 0; "param_diag_sanitizer_tsan_stopOnIssue" = 0; "param_diag_sanitizer_ubsan_enable" = 0; "param_diag_sanitizer_ubsan_stopOnIssue" = 0; "param_diag_showNonLocalizedStrings" = 0; "param_diag_viewDebugging_enabled" = 1; "param_diag_viewDebugging_insertDylibOnLaunch" = 1; "param_install_style" = 2; "param_launcher_UID" = 2; "param_launcher_allowDeviceSensorReplayData" = 0; "param_launcher_kind" = 0; "param_launcher_style" = 99; "param_launcher_substyle" = 0; "param_lldbVersion_component_idx_1" = 0; "param_lldbVersion_monotonic" = 170300230950; "param_runnable_appExtensionHostRunMode" = 0; "param_runnable_productType" = "com.apple.product-type.application"; "param_testing_launchedForTesting" = 0; "param_testing_suppressSimulatorApp" = 0; "param_testing_usingCLI" = 0; "sdk_canonicalName" = "iphoneos26.0"; "sdk_osVersion" = "26.0"; "sdk_platformID" = 2; "sdk_variant" = iphoneos; "sdk_version_monotonic" = 2300527605; } System Information macOS Version 15.5 (Build 24F74) Xcode 26.0 (24141.31) (Build 17A5241o) Timestamp: 2025-09-17T18:26:56+08:00
3
0
209
Sep ’25
Extra-ordinary Networking
Most apps perform ordinary network operations, like fetching an HTTP resource with URLSession and opening a TCP connection to a mail server with Network framework. These operations are not without their challenges, but they’re the well-trodden path. If your app performs ordinary networking, see TN3151 Choosing the right networking API for recommendations as to where to start. Some apps have extra-ordinary networking requirements. For example, apps that: Help the user configure a Wi-Fi accessory Require a connection to run over a specific interface Listen for incoming connections Building such an app is tricky because: Networking is hard in general. Apple devices support very dynamic networking, and your app has to work well in whatever environment it’s running in. Documentation for the APIs you need is tucked away in man pages and doc comments. In many cases you have to assemble these APIs in creative ways. If you’re developing an app with extra-ordinary networking requirements, this post is for you. Note If you have questions or comments about any of the topics discussed here, put them in a new thread here on DevForums. Make sure I see it by putting it in the App & System Services > Networking area. And feel free to add tags appropriate to the specific technology you’re using, like Foundation, CFNetwork, Network, or Network Extension. Links, Links, and More Links Each topic is covered in a separate post: The iOS Wi-Fi Lifecycle describes how iOS joins and leaves Wi-Fi networks. Understanding this is especially important if you’re building an app that works with a Wi-Fi accessory. Network Interface Concepts explains how Apple platforms manage network interfaces. If you’ve got this far, you definitely want to read this. Network Interface Techniques offers a high-level overview of some of the more common techniques you need when working with network interfaces. Network Interface APIs describes APIs and core techniques for working with network interfaces. It’s referenced by many other posts. Running an HTTP Request over WWAN explains why most apps should not force an HTTP request to run over WWAN, what they should do instead, and what to do if you really need that behaviour. If you’re building an iOS app with an embedded network server, see Showing Connection Information in an iOS Server for details on how to get the information to show to your user so they can connect to your server. Many folks run into trouble when they try to find the device’s IP address, or other seemingly simple things, like the name of the Wi-Fi interface. Don’t Try to Get the Device’s IP Address explains why these problems are hard, and offers alternative approaches that function correctly in all network environments. Similarly, folks also run into trouble when trying to get the host name. On Host Names explains why that’s more complex than you might think. If you’re working with broadcasts or multicasts, see Broadcasts and Multicasts, Hints and Tips. If you’re building an app that works with a Wi-Fi accessory, see Working with a Wi-Fi Accessory. If you’re trying to gather network interface statistics, see Network Interface Statistics. There are also some posts that are not part of this series but likely to be of interest if you’re working in this space: TN3179 Understanding local network privacy discusses the local network privacy feature. Calling BSD Sockets from Swift does what it says on the tin, that is, explains how to call BSD Sockets from Swift. When doing weird things with the network, you often find yourself having to use BSD Sockets, and that API is not easy to call from Swift. The code therein is primarily for the benefit of test projects, oh, and DevForums posts like these. TN3111 iOS Wi-Fi API overview is a critical resource if you’re doing Wi-Fi specific stuff on iOS. TLS For Accessory Developers tackles the tricky topic of how to communicate securely with a network-based accessory. A Peek Behind the NECP Curtain discusses NECP, a subsystem that control which programs have access to which network interfaces. Networking Resources has links to many other useful resources. Share and Enjoy — Quinn “The Eskimo!” @ Developer Technical Support @ Apple let myEmail = "eskimo" + "1" + "@" + "apple.com" Revision History 2025-07-31 Added a link to A Peek Behind the NECP Curtain. 2025-03-28 Added a link to On Host Names. 2025-01-16 Added a link to Broadcasts and Multicasts, Hints and Tips. Updated the local network privacy link to point to TN3179. Made other minor editorial changes. 2024-04-30 Added a link to Network Interface Statistics. 2023-09-14 Added a link to TLS For Accessory Developers. 2023-07-23 First posted.
0
0
5.7k
Jul ’25
Symbol not found: ___res_9_state
When running my app with Xcode16.4, it crashed with the error: dyld[1045]: Symbol not found: ___res_9_state Referenced from: <8B329554-5BEF-38D0-BFCD-1731FA6120CB> /private/var/containers/Bundle/Application/00C941BA-E397-4D0B-B280-E75583FF2890/xxx.app/xxx.debug.dylib Expected in: <7D74C679-8F55-3A01-9AA2-C205A4A19D3E> /usr/lib/libresolv.9.dylib The ___res_9_state related code in my app is: let state = __res_9_state() res_9_ninit(state) var servers = [res_9_sockaddr_union](repeating: res_9_sockaddr_union(), count: Int(MAXNS)) let found = Int(res_9_getservers(state, &servers, Int32(MAXNS))) res_9_nclose(state) if found > 0 { return Array(servers[0..<found]).filter() { $0.sin.sin_len > 0 } } else { return [] } Previously, __res_9_state() could run normally in Xcode 16.1 How to fix this problem?
2
0
181
Jul ’25
Network Interface APIs
For important background information, read Extra-ordinary Networking before reading this. Share and Enjoy — Quinn “The Eskimo!” @ Developer Technical Support @ Apple let myEmail = "eskimo" + "1" + "@" + "apple.com" Network Interface APIs Most developers don’t need to interact directly with network interfaces. If you do, read this post for a summary of the APIs available to you. Before you read this, read Network Interface Concepts. Interface List The standard way to get a list of interfaces and their addresses is getifaddrs. To learn more about this API, see its man page. A network interface has four fundamental attributes: A set of flags — These are packed into a CUnsignedInt. The flags bits are declared in <net/if.h>, starting with IFF_UP. An interface type — See Network Interface Type, below. An interface index — Valid indexes are greater than 0. A BSD interface name. For example, an Ethernet interface might be called en0. The interface name is shared between multiple network interfaces running over a given hardware interface. For example, IPv4 and IPv6 running over that Ethernet interface will both have the name en0. WARNING BSD interface names are not considered API. There’s no guarantee, for example, that an iPhone’s Wi-Fi interface is en0. You can map between the last two using if_indextoname and if_nametoindex. See the if_indextoname man page for details. An interface may also have address information. If present, this always includes the interface address (ifa_addr) and the network mask (ifa_netmask). In addition: Broadcast-capable interfaces (IFF_BROADCAST) have a broadcast address (ifa_broadaddr, which is an alias for ifa_dstaddr). Point-to-point interfaces (IFF_POINTOPOINT) have a destination address (ifa_dstaddr). Calling getifaddrs from Swift is a bit tricky. For an example of this, see QSocket: Interfaces. IP Address List Once you have getifaddrs working, it’s relatively easy to manipulate the results to build a list of just IP addresses, a list of IP addresses for each interface, and so on. QSocket: Interfaces has some Swift snippets that show this. Interface List Updates The interface list can change over time. Hardware interfaces can be added and removed, network interfaces come up and go down, and their addresses can change. It’s best to avoid caching information from getifaddrs. If thats unavoidable, use the kNotifySCNetworkChange Darwin notification to update your cache. For information about registering for Darwin notifications, see the notify man page (in section 3). This notification just tells you that something has changed. It’s up to you to fetch the new interface list and adjust your cache accordingly. You’ll find that this notification is sometimes posted numerous times in rapid succession. To avoid unnecessary thrashing, debounce it. While the Darwin notification API is easy to call from Swift, Swift does not import kNotifySCNetworkChange. To fix that, define that value yourself, calling a C function to get the value: var kNotifySCNetworkChange: UnsafePointer<CChar> { networkChangeNotifyKey() } Here’s what that C function looks like: extern const char * networkChangeNotifyKey(void) { return kNotifySCNetworkChange; } Network Interface Type There are two ways to think about a network interface’s type. Historically there were a wide variety of weird and wonderful types of network interfaces. The following code gets this legacy value for a specific BSD interface name: func legacyTypeForInterfaceNamed(_ name: String) -> UInt8? { var addrList: UnsafeMutablePointer<ifaddrs>? = nil let err = getifaddrs(&addrList) // In theory we could check `errno` here but, honestly, what are gonna // do with that info? guard err >= 0, let first = addrList else { return nil } defer { freeifaddrs(addrList) } return sequence(first: first, next: { $0.pointee.ifa_next }) .compactMap { addr in guard let nameC = addr.pointee.ifa_name, name == String(cString: nameC), let sa = addr.pointee.ifa_addr, sa.pointee.sa_family == AF_LINK, let data = addr.pointee.ifa_data else { return nil } return data.assumingMemoryBound(to: if_data.self).pointee.ifi_type } .first } The values are defined in <net/if_types.h>, starting with IFT_OTHER. However, this value is rarely useful because many interfaces ‘look like’ Ethernet and thus have a type of IFT_ETHER. Network framework has the concept of an interface’s functional type. This is an indication of how the interface fits into the system. There are two ways to get an interface’s functional type: If you’re using Network framework and have an NWInterface value, get the type property. If not, call ioctl with a SIOCGIFFUNCTIONALTYPE request. The return values are defined in <net/if.h>, starting with IFRTYPE_FUNCTIONAL_UNKNOWN. Swift does not import SIOCGIFFUNCTIONALTYPE, so it’s best to write this code in a C: extern uint32_t functionalTypeForInterfaceNamed(const char * name) { int fd = socket(AF_INET, SOCK_DGRAM, 0); if (fd < 0) { return IFRTYPE_FUNCTIONAL_UNKNOWN; } struct ifreq ifr = {}; strlcpy(ifr.ifr_name, name, sizeof(ifr.ifr_name)); bool success = ioctl(fd, SIOCGIFFUNCTIONALTYPE, &ifr) >= 0; int junk = close(fd); assert(junk == 0); if ( ! success ) { return IFRTYPE_FUNCTIONAL_UNKNOWN; } return ifr.ifr_ifru.ifru_functional_type; } Finally, TN3158 Resolving Xcode 15 device connection issues documents the SIOCGIFDIRECTLINK flag as a specific way to identify the network interfaces uses by Xcode for device connection traffic. Revision History 2025-12-10 Added info about SIOCGIFDIRECTLINK. 2023-07-19 First posted.
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2.1k
Dec ’25
Need Help with TUN Writeback
Hi everyone, I'm currently experimenting with building a simple DNS filter using Apple's Packet Tunnel framework. Here's the flow I'm trying to implement: Create a TUN interface Set up a UDP socket Read packets via packetFlow.readPackets Parse the raw IP packet Forward the UDP payload through the socket Receive the response from the server Reconstruct the IP packet with the response Write it back to the TUN interface using packetFlow.writePackets Here’s an example of an intercepted IP packet (DNS request): 45 00 00 3c 15 c4 00 00 40 11 93 d1 c0 a8 00 64 08 08 08 08 ed 6e 00 35 00 28 e5 c9 7f da 01 00 00 01 00 00 00 00 00 00 04 74 69 6d 65 05 61 70 70 6c 65 03 63 6f 6d 00 00 01 00 01 And here’s the IP packet I tried writing back into the TUN interface (DNS response): 45 00 00 89 5e 37 40 00 40 11 0b 11 08 08 08 08 c0 a8 00 64 00 35 ed 6e 00 75 91 e8 7f da 81 80 00 01 00 04 00 00 00 00 04 74 69 6d 65 05 61 70 70 6c 65 03 63 6f 6d 00 00 01 00 01 c0 0c 00 05 00 01 00 00 0c fb 00 11 04 74 69 6d 65 01 67 07 61 61 70 6c 69 6d 67 c0 17 c0 2c 00 01 00 01 00 00 03 04 00 04 11 fd 74 fd c0 2c 00 01 00 01 00 00 03 04 00 04 11 fd 74 7d c0 2c 00 01 00 01 00 00 03 04 00 04 11 fd 54 fb Unfortunately, it seems the packet is not being written back correctly to the TUN interface. I'm not seeing any expected DNS response behavior on the device. Also, I noticed that after creating the TUN, the interface address shows up as 0.0.0.0:0 in Xcode. The system log includes this message when connecting the VPN: NWPath does not have valid interface: satisfied (Path is satisfied), interface: utun20[endc_sub6], ipv4, dns, expensive, uses cellular Does anyone know how to properly initialize the TUN so that the system recognizes it with a valid IP configuration? Or why my written-back packet might be getting ignored? Any help would be appreciated!
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87
Jul ’25
Securely transmit UIImage to app running on desktop website
Hello everyone, I'm trying to figure out how to transmit a UIImage (png or tiff) securely to an application running in my desktop browser (Mac or PC). The desktop application and iOS app would potentially be running on the same local network (iOS hotspot or something) or have no internet connection at all. I'm trying to securely send over an image that the running desktop app could ingest. I was thinking something like a local server securely accepting image data from an iPhone. Any suggestions ideas or where to look for more info would be greatly appreciated! Thank you for your help.
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124
May ’25
Network Relay errors out with "Privacy proxy failed with error 53"
I'm using NERelayManager to set Relay configuration which all works perfectly fine. I then do a curl with the included domain and while I see QUIC connection succeeds with relay server and H3 request goes to the server, the connection gets abruptly closed by the client with "Software caused connection abort". Console has this information: default 09:43:04.459517-0700 curl nw_flow_connected [C1.1.1 192.168.4.197:4433 in_progress socket-flow (satisfied (Path is satisfied), viable, interface: en0[802.11], ipv4, ipv6, dns, uses wifi)] Transport protocol connected (quic) default 09:43:04.459901-0700 curl [C1.1.1 192.168.4.197:4433 in_progress socket-flow (satisfied (Path is satisfied), viable, interface: en0[802.11], ipv4, ipv6, dns, uses wifi)] event: flow:finish_transport @0.131s default 09:43:04.460745-0700 curl nw_flow_connected [C1.1.1 192.168.4.197:4433 in_progress socket-flow (satisfied (Path is satisfied), viable, interface: en0[802.11], ipv4, ipv6, dns, uses wifi)] Joined protocol connected (http3) default 09:43:04.461049-0700 curl [C1.1.1 192.168.4.197:4433 in_progress socket-flow (satisfied (Path is satisfied), viable, interface: en0[802.11], ipv4, ipv6, dns, uses wifi)] event: flow:finish_transport @0.133s default 09:43:04.465115-0700 curl [C2 E47A3A0C-7275-4F6B-AEDF-59077ABAE34B 192.168.4.197:4433 quic, multipath service: 1, tls, definite, attribution: developer] cancel default 09:43:04.465238-0700 curl [C2 E47A3A0C-7275-4F6B-AEDF-59077ABAE34B 192.168.4.197:4433 quic, multipath service: 1, tls, definite, attribution: developer] cancelled [C2 FCB1CFD1-4BF9-4E37-810E-81265D141087 192.168.4.139:53898<->192.168.4.197:4433] Connected Path: satisfied (Path is satisfied), viable, interface: en0[802.11], ipv4, ipv6, dns, uses wifi Duration: 0.121s, QUIC @0.000s took 0.000s, TLS 1.3 took 0.111s bytes in/out: 2880/4322, packets in/out: 4/8, rtt: 0.074s, retransmitted bytes: 0, out-of-order bytes: 0 ecn packets sent/acked/marked/lost: 3/1/0/0 default 09:43:04.465975-0700 curl nw_flow_disconnected [C2 192.168.4.197:4433 cancelled multipath-socket-flow ((null))] Output protocol disconnected default 09:43:04.469189-0700 curl nw_endpoint_proxy_receive_report [C1.1 IPv4#124bdc4d:80 in_progress proxy (satisfied (Path is satisfied), interface: en0[802.11], ipv4, ipv6, dns, proxy, uses wifi)] Privacy proxy failed with error 53 ([C1.1.1] masque Proxy: http://192.168.4.197:4433) default 09:43:04.469289-0700 curl [C1.1.1 192.168.4.197:4433 failed socket-flow (satisfied (Path is satisfied), viable, interface: en0[802.11], ipv4, ipv6, dns, uses wifi)] event: flow:failed_connect @0.141s, error Software caused connection abort Relay server otherwise works fine with our QUIC MASQUE clients but not with built-in macOS MASQUE client. Anything I'm missing?
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222
May ’25
XPC Connection with Network Extension fails after upgrade
Hi Team, I have a Network Extension application and UI frontend for it. The UI frontend talks to the Network Extension using XPC, as provided by NEMachServiceName. On M2 machine, The application and XPC connection works fine on clean installation. But, when the application is upgraded, the XPC connection keeps failing. Upgrade steps: PreInstall script kills the running processes, both UI and Network Extension Let installation continue PostInstall script to launch the application after installation complete. Following code is successful to the point of resume from UI application NSXPCInterface *exportedInterface = [NSXPCInterface interfaceWithProtocol:@protocol(IPCUIObject)]; newConnection.exportedInterface = exportedInterface; newConnection.exportedObject = delegate; NSXPCInterface *remoteObjectInterface = [NSXPCInterface interfaceWithProtocol:@protocol(IPCExtObject)]; newConnection.remoteObjectInterface = remoteObjectInterface; self.currentConnection = newConnection; [newConnection resume]; But it fails to get the object id<IPCExtObject> providerProxy = [self.currentConnection remoteObjectProxyWithErrorHandler:^(NSError *registerError) { }]; Please note, this only fails for M2. For M1, this exact code is running fine. Additionally, if I uninstall the application by dropping it in Trash and then installing the newer version, then too, the application works fine.
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967
Dec ’25
Network Extension Resources
General: Forums subtopic: App & System Services > Networking DevForums tag: Network Extension Network Extension framework documentation Routing your VPN network traffic article Filtering traffic by URL sample code Filtering Network Traffic sample code TN3120 Expected use cases for Network Extension packet tunnel providers technote TN3134 Network Extension provider deployment technote TN3165 Packet Filter is not API technote Network Extension and VPN Glossary forums post Debugging a Network Extension Provider forums post Exporting a Developer ID Network Extension forums post Network Extension Framework Entitlements forums post Network Extension vs ad hoc techniques on macOS forums post Network Extension Provider Packaging forums post NWEndpoint History and Advice forums post Extra-ordinary Networking forums post Wi-Fi management: Wi-Fi Fundamentals forums post TN3111 iOS Wi-Fi API overview technote How to modernize your captive network developer news post iOS Network Signal Strength forums post See also Networking Resources. Share and Enjoy — Quinn “The Eskimo!” @ Developer Technical Support @ Apple let myEmail = "eskimo" + "1" + "@" + "apple.com"
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3.1k
Jan ’26
Wi-Fi Aware Paring Flow
Hello, I understand that to discover and pair a device or accessory with Wi-Fi Aware, we can use either the DeviceDiscoveryUI or AccessorySetupKitUI frameworks. During the pairing process, both frameworks prompt the user to enter a pairing code. Is this step mandatory? What alternatives exist for devices or accessories that don't have a way to communicate a pairing code to the user (for example, devices or accessories without a display or voice capability)? Best regards, Gishan
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331
Nov ’25
intermittent multicast socket failures, new to Sequoia, still not fixed
multicast sockets fail to send/receive on macosx, errno 65 "no route to host". Wireshark and Terminal.app (which have root privileges) both show incoming multicast traffic just fine. Normal UDP broadcast sockets have no problems. Toggling the Security&Privacy -> Local Network setting may fix the problem for some Users. There is no pattern for when multicast socket fails. Sometimes, recreating the sockets fix the problem. Restart the app, sometimes multicast fails, sometimes success (intermittent, no pattern). Reboot machine (intermittent fail) Create a fresh new user on machine, install single version of app, give app permission. (intermittent fail, same as above). We have all the normal entitlements / notarized app. Similar posts here see FB16923535, Related to FB16512666 https://forum.xojo.com/t/udp-multicast-receive-on-mac-failing-intermittant/83221 see my post from 2012 "distinguishing between SENDING sockets and RECEIVING sockets" for source code example of how we bind multicast sockets. Our other socket code is standard "Stevens, et al." code. The bind() is the call that fails in this case. https://stackoverflow.com/questions/10692956/what-does-it-mean-to-bind-a-multicast-udp-socket . Note that this post from 2012 is still relevant, and that it is a workaround to a longstanding Apple bug that was never fixed. Namely, "Without this fix, multicast sending will intermittently get sendto() errno 'No route to host'. If anyone can shed light on why unplugging a DHCP gateway causes Mac OS X multicast SENDING sockets to get confused, I would love to hear it." This may be a hint as to the underlying bug that Apple really needs to fix, but if it's not, then please Apple, fix the Sequoia bug first. These are probably different bugs because in one case, sendto() fails when a socket becomes "unbound" after you unplug an unrelated network cable. In this case, bind() fails, so sendto() is never even called. Note, that we have also tried to use other implementations for network discovery, including Bonjour, CFNetwork, etc. Bonjour fails intermittently, and also suffers from both bugs mentioned above, amongst others.
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112
May ’25