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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.

Networking Documentation

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Background Download Support for Large Video Files in visionOS App
Hi everyone, I'm developing a visionOS app that allows users to download large video files (similar to a movie download experience, with each file being around 10 GB). I've successfully implemented the core video download functionality using URLSession, and everything works as expected while the app is active. Now, I’m looking to support background downloading. Specifically, I want users to be able to start a download and then leave the app (e.g., switch apps or return to the home screen) while the download continues in the background. Additionally, I’d like to confirm a specific scenario: If the user starts a download, then removes the headset (keeping the device turned on and connected to power), will the download continue in the background? Or does visionOS suspend the app or downloads in this case? I’m considering using a background URLSessionConfiguration (as done in iOS/macOS) to enable this behavior, but I’m not sure if it behaves the same way on visionOS or if there are special limitations or best practices when handling large downloads on this platform. Any insights or official guidance would be greatly appreciated! Thanks!
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68
May ’25
Technical Inquiry about CoreBluetooth Scanning & NEHotspotConfigurationManager Workflow
I am writing to seek clarification on two technical issues related to iOS frameworks (CoreBluetooth and NetworkExtension). These observations are critical for optimizing our app's performance, and I would appreciate any official guidance or documentation references. CoreBluetooth Scanning Frequency and Cycle Issue: We noticed inconsistent BLE device discovery times (ranging from 0.5s to 1.5s) despite the peripheral advertising at 2Hz (500ms interval). Questions: Does iOS regulate the BLE scan interval or duty cycle internally? If yes, what factors affect this behavior (e.g., foreground/background state, connected devices)? Are there recommended practices to reduce discovery latency for peripherals with fixed advertising intervals? Is there a way to configure scan parameters (e.g., scan window/interval) programmatically, similar to Android's BluetoothLeScanner? Test Context: Device: iPhone 13 mini (iOS 17.6.1) Code: CBCentralManager.scanForPeripherals(withServices: nil, options: [CBCentralManagerScanOptionAllowDuplicatesKey: true]) NEHotspotConfigurationManager Workflow and Latency Issue: Using NEHotspotConfigurationManager.shared.apply(_:) to connect to Wi-Fi occasionally takes up to 8 seconds to complete. Questions: What is the internal workflow of the apply method? Does it include user permission checks, SSID scanning, authentication, or IP assignment steps? Are there known scenarios where this method would block for extended periods (e.g., waiting for user interaction, network timeouts)? Is the latency related to system-level retries or radio coexistence with other wireless activities (e.g., Bluetooth)? Test Context: Configuration: NEHotspotConfiguration(ssid: "TestSSID") Behavior: Delay occurs even when the Wi-Fi network is in range and credentials are correct.
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172
Mar ’25
Getting connection settings from method handleNewUDPFlow
I'm using NETransparentProxyProvider to intercept udp sockets using the method handleNewUDPFlow. An application may create a UDP socket and set the DONTFRAG using setsockopt method setsockopt(s, IPPROTO_IP, IP_DONTFRAG, &val, sizeof(val)) In this case, do I have option in this case, to get the connection settings inside the callback (void)handleNewUDPFlow:(NEAppProxyUDPFlow *)flow initialRemoteEndpoint:(NWEndpoint *)remoteEndpoint; So in this case, I would be able to create the outgoing socket with the exact same characteristics, after the original app socket got intercepted by my proxy provider ?
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356
Feb ’25
Disabling Fragmented Packets on NWConnection - What Is Expected from disableFragmentation?
Hello everyone, We have a use case where we need to disable the sending and receiving of fragmented packets on the network while using NWConnection. However, even after setting the disableFragmentation flag to true, the connection still sends fragmented packets.We’ve tried setting the flag as follows, but the packets are still being fragmented: var connection : NWConnection var udp_options : NWProtocolUDP.Optionsudp_options = NWProtocolUDP.Options() var connection_parameters = NWParameters(dtls: nil, udp: udp_options) let ip_options = connection_parameters.defaultProtocolStack.internetProtocol! as! NWProtocolIP.Options ip_options.disableFragmentation = true connection = NWConnection (host: "XX.XX.XX.***", port: NWEndpoint.Port(25000), using: connection_parameters) The issue we are encountering is that even though we’ve set disableFragmentation to true on the sender, the receiver still receives fragmented UDP packets. This can be observed using Wireshark, where we are sending a 10k byte data from the sender and receiving the fragmented datagram packets on the receiver end while both the devices are on the same WiFi network. Additionally, Wireshark shows that the packet has the "DF" bit set to '0', indicating that fragmentation is allowed. What is exactly expected from the disableFragmentation flag? Are we misunderstanding how this flag works? Or is there something else we should be doing to ensure that fragmentation is completely disabled? Looking forward to your insights!
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308
Dec ’24
Behavior of Pending Receive Callbacks on Canceled NWConnection (UDP) Registered to Custom Serial Dispatch Queue
Hi Everyone, I’m working on a communication system for my app using NWConnection with the UDP protocol. The connection is registered to a custom serial dispatch queue. However, I’m trying to understand what the behavior will be in a scenario where the connection is canceled while there are still pending receive operations in progress. Scenario Overview: The sender is transmitting n = 100 packets to the receiver, out of which 40 packets have already been sent (i.e., delivered to the Receiver). The receiver has posted m = 20 pending receive operations, where each receive operation is responsible for handling one packet. The receiver has already successfully processed x = 10 packets. At the time of cancellation, the receiver’s buffer still holds m = 20 packets that are pending for processing, and k = 10 pending receive callbacks are in the dispatch queue, waiting to be executed. At same time when the 10th packet was processed another thread triggers .cancel() on this accepted NWConnection (on the receiver side), I need to understand the impact on the pending receive operations and their associated callbacks. My Questions: What happens to the k = 10 pending receive callbacks that are in the dispatch queue waiting to be triggered when the connection is canceled? Will these callbacks complete successfully and process the data? Or, because the connection is canceled, will they complete with failure? What happens to the remaining pending receive operations that were initiated but have not yet been scheduled in the dispatch queue? For the pending receive operations that were already initiated (i.e., the network stack is waiting to receive the data, but the callback hasn’t been scheduled yet), will they fail immediately when the connection is canceled? Or is there any chance that the framework might still process these receives before the cancellation fully takes effect?
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313
Feb ’25
Error Domain=NSURLErrorDomain Code=-1009
When I make a local network HTTP request, an error occurs. I'm sure I've granted wireless data permissions and local network permissions, and I'm connected to the correct Wi-Fi. This problem is intermittent, but once it happens, it will keep happening, and the only way to fix it is to restart the phone. Here is the error log: sessionTaskFailed(error: Error Domain=NSURLErrorDomain Code=-1009 "似乎已断开与互联网的连接。" UserInfo={_kCFStreamErrorCodeKey=50, NSUnderlyingError=0x30398a5b0 {Error Domain=kCFErrorDomainCFNetwork Code=-1009 "(null)" UserInfo={_NSURLErrorNWPathKey=unsatisfied (Local network prohibited), interface: en0[802.11], uses wifi, _kCFStreamErrorCodeKey=50, _kCFStreamErrorDomainKey=1}}, _NSURLErrorFailingURLSessionTaskErrorKey=LocalDataTask .<63>, _NSURLErrorRelatedURLSessionTaskErrorKey=( "LocalDataTask .<63>" ), NSLocalizedDescription=似乎已断开与互联网的连接。, NSErrorFailingURLStringKey=http://192.168.2.1:80/v1/parameters, NSErrorFailingURLKey=http://192.168.2.1:80/v1/parameters, _kCFStreamErrorDomainKey=1})
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160
Mar ’25
[MacOS] regular disconnections in enterprise network
Hi, I am working on a case in our organisation where hundreds if not a thousand wireless network clients are affected by regular, usually 30 sometimes 60 minute sometime they are unnoticeable but often people having meetings notice that a lot. We excluded wireless network configuration issue since disconnections happens to clients both connected to Cisco and Ubiquiti Access Points. WLC logs mostly show EAP timeout errors - clients are getting disauthenticated and authenticated back - usually without any action needed - but the meeting is being interrupted. What I found in Macbook logs with sudo log show [options] is the main reason of network disconnection: 2025-02-04 14:16:31.219192+0100 0xc01342 Default 0x0 86459 0 wifianalyticsd: [com.apple.wifi.analytics:Default] -[DPSQuickRecoveryRecommendationEngine updateTimeSincePreviousTriggerForStudy:msgKey:dictKey:]::913:msgkey:WFAAWDWASDS_symptomsDnsTimeSincePreviousTriggerMinutes dictKey:dps_lastSymptomsDpsTrigger previous_TS:(null) current_TS:Tue Feb 4 14:16:31 2025 difference:0 2025-02-04 14:16:31.219704+0100 0xc01342 Default 0x0 86459 0 wifianalyticsd: [com.apple.wifi.analytics:Default] -[DPSQuickRecoveryRecommendationEngine updateScreenState]::198:DPS Fast Reset Recommendation Engine: (screenON & foreGrnd traffic) is DETECTED 2025-02-04 14:16:31.219713+0100 0xc01342 Default 0x0 86459 0 wifianalyticsd: [com.apple.wifi.analytics:Default] -[DPSQuickRecoveryRecommendationEngine recommendSymptomsDpsRecovery:symptomsDnsStats:awdlState:currentSymptomsCondition:isLANPingSuccessful:appUsage:averageCCA:]::966:PeerDiagnostics: Data not received from peerDiagnostics 2025-02-04 14:16:31.219714+0100 0xc01342 Default 0x0 86459 0 wifianalyticsd: [com.apple.wifi.analytics:Default] -[DPSQuickRecoveryRecommendationEngine checkForPriorityNetwork]::256:Priority Network Check Disabled: NO IsPriorityNetwork: YES 2025-02-04 14:16:31.219732+0100 0xc01342 Default 0x0 86459 0 wifianalyticsd: [com.apple.wifi.analytics:Default] -[DPSQuickRecoveryRecommendationEngine isResetAllowedForKey:forPrefSelector:]::330:key:symptomsDps_lastScreenOnRecoveryWD previousWD_TS:(null) currentWD_TS:Tue Feb 4 14:16:31 2025 recommendation:YES 2025-02-04 14:16:31.219735+0100 0xc01342 Default 0x0 86459 0 wifianalyticsd: [com.apple.wifi.analytics:Default] -[DPSQuickRecoveryRecommendationEngine updateSymptomsDPSRecoveryWDStatsForKey:]::210:Added key: symptomsDps_numRecommendedScreenOnRecoveryWD value:1 dict:(null) 2025-02-04 14:16:31.219737+0100 0xc01342 Default 0x0 86459 0 wifianalyticsd: [com.apple.wifi.analytics:Default] -[DPSQuickRecoveryRecommendationEngine recommendSymptomsDpsRecovery:symptomsDnsStats:awdlState:currentSymptomsCondition:isLANPingSuccessful:appUsage:averageCCA:]::1023:PeerDiagnostics: Recommendation for DNS Symptoms Recovery: Reassoc Do you guys have any idea where can I see that DNS symptoms? I can also see some reading like: 2025-02-04 14:16:31.219169+0100 0xc01342 Default 0x0 86459 0 wifianalyticsd: [com.apple.wifi.analytics:Default] -[WAEngine gatherConsecutiveDatapathReadings:forProcessToken:andReply:]_block_invoke::4235:DNS Symptoms pre-decision check:: Associated:YES Primary:YES isCaptive:NO isValidDnsConfig:YES 2025-02-04 14:16:31.219169+0100 0xc01342 Default 0x0 86459 0 wifianalyticsd: [com.apple.wifi.analytics:Default] -[WAEngine gatherConsecutiveDatapathReadings:forProcessToken:andReply:]_block_invoke::4238:SDNS: WiFi Not Primary - setting suppressedReason kSymptomsDnsWiFiInterfaceNotPrimary WiFi Not Primary - how if this is my only interface? - I removed all other Killing and disabling wifianalyticsd does not help - the process is being spawned by launchd on airportd request: 2025-02-04 08:54:11.903825+0100 0xb85274 Default 0x0 627 0 airportd: (WiFiAnalytics) [com.apple.wifi.analytics:Default] -[WAClient _establishDaemonConnection]_block_invoke::1057:XPC: establishing connection to daemon with token ending in: <private>... 2025-02-04 08:54:11.907779+0100 0xb8504a Default 0x0 627 0 airportd: (IO80211) [com.apple.WiFiManager:] Info: <airport[627]> -[dpsManager submitDpsSymptom:isCriticalApp:]_block_invoke: 2025-02-04 08:54:11.907943+0100 0xb8504a Default 0x0 627 0 airportd: (IO80211) -[dpsManager submitDpsSymptom:isCriticalApp:]_block_invoke: Error preparing DPSNotification for submission: Error Domain=com.apple.wifi.analytics.errordomain Code=9014 "WAErrorCodeDaemonContactTimeout" UserInfo={NSLocalizedFailureReason=WAErrorCodeDaemonContactTimeout}, or null WAMessageAWD 2025-02-04 08:54:11.908055+0100 0xb8504a Default 0x0 627 0 airportd: (IO80211) [com.apple.WiFiManager:] <airport[627]> -[dpsManager submitDpsSymptom:isCriticalApp:]_block_invoke: Error preparing DPSNotification for submission: Error Domain=com.apple.wifi.analytics.errordomain Code=9014 "WAErrorCodeDaemonContactTimeout" UserInfo={NSLocalizedFailureReason=WAErrorCodeDaemonContactTimeout}, or null WAMessageAWD 2025-02-04 08:54:11.910453+0100 0xb85274 Default 0x0 627 0 airportd: (libxpc.dylib) [com.apple.xpc:connection] [0x80fe64640] activating connection: mach=true listener=false peer=false name=com.apple.wifianalyticsd 2025-02-04 08:54:11.911105+0100 0xb85382 Default 0x0 1 0 launchd: [system/com.apple.wifianalyticsd:] internal event: WILL_SPAWN, code = 0 2025-02-04 08:54:11.911229+0100 0xb85382 Default 0x0 1 0 launchd: [system/com.apple.wifianalyticsd:] service state: spawn scheduled 2025-02-04 08:54:11.911233+0100 0xb85382 Default 0x0 1 0 launchd: [system/com.apple.wifianalyticsd:] service state: spawning 2025-02-04 08:54:11.911384+0100 0xb85382 Default 0x0 1 0 launchd: [system/com.apple.wifianalyticsd:] launching: ipc (mach) 2025-02-04 08:54:11.920272+0100 0xb85382 Default 0x0 1 0 launchd: [system/com.apple.wifianalyticsd [86459]:] xpcproxy spawned with pid 86459 Do you guys have any idea what is the cause of this behaviour? Or how to disable wifianalyticsd process for good?
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216
Feb ’25
Unable to update app with PacketTunnelProvider running
Hi there, I am working on an app that configures a PacketTunnelProvider to establish a VPN connection. Unfortunately, while a VPN connection is established, I am unable to update the app via testflight. Downloading other app updates works fine. I noticed that after I receive the alert that updating failed, the vpn badge appears at the top of my screen (the same ux that occurs when the connection is first established). So it's almost like it tried to close the tunnel, and seeing that the app update failed it restablishes the tunnel. I am unsure of why I would not be able to update my app. Maybe stopTunnel is not being called with NEProviderStopReason.appUpdate?
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48
Jun ’25
Writing an `NWProtocolFramerImplementation` to run on top of `NWProtocolWebSocket`
Hi All, I am trying to write an NWProtocolFramerImplementation that will run after Websockets. I would like to achieve two goals with this Handle the application-layer authentication handshake in-protocol so my external application code can ignore it Automatically send pings periodically so my application can ignore keepalive I am running into trouble because the NWProtocolWebsocket protocol parses websocket metadata into NWMessage's and I don't see how to handle this at the NWProtocolFramerImplementation level Here's what I have (see comments for questions) class CoolProtocol: NWProtocolFramerImplementation { static let label = "Cool" private var tempStatusCode: Int? required init(framer: NWProtocolFramer.Instance) {} static let definition = NWProtocolFramer.Definition(implementation: CoolProtocol.self) func start(framer: NWProtocolFramer.Instance) -> NWProtocolFramer.StartResult { return .willMarkReady } func wakeup(framer: NWProtocolFramer.Instance) { } func stop(framer: NWProtocolFramer.Instance) -> Bool { return true } func cleanup(framer: NWProtocolFramer.Instance) { } func handleOutput(framer: NWProtocolFramer.Instance, message: NWProtocolFramer.Message, messageLength: Int, isComplete: Bool) { // How to write a "Message" onto the next protocol handler. I don't want to just write plain data. // How to tell the websocket protocol framer that it's a ping/pong/text/binary... } func handleInput(framer: NWProtocolFramer.Instance) -> Int { // How to handle getting the input from websockets in a message format? I don't want to just get "Data" I would like to know if that data is // a ping, pong, text, binary, ... } } If I implementing this protocol at the application layer, here's how I would send websocket messages class Client { ... func send(string: String) async throws { guard let data = string.data(using: .utf8) else { return } let metadata = NWProtocolWebSocket.Metadata(opcode: .text) let context = NWConnection.ContentContext( identifier: "textContext", metadata: [metadata] ) self.connection.send( content: data, contentContext: context, isComplete: true, completion: .contentProcessed({ [weak self] error in ... }) ) } } You see at the application layer I have access to this context object and can access NWProtocolMetadata on the input and output side, but in NWProtocolFramer.Instance I only see final func writeOutput(data: Data) which doesn't seem to include context anywhere. Is this possible? If not how would you recommend I handle this? I know I could re-write the entire Websocket protocol framer, but it feels like I shouldn't have to if framers are supposed to be able to stack.
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283
Jan ’25
IOS VPN APP DEPLOYMENT
Hi everyone, I developed an Android version of a VPN app built with Flutter using OpenVPN, and it works perfectly on Android. However, when porting it to iOS, I’ve encountered an issue: the app connects successfully but then automatically disconnects when tested via TestFlight. We’ve already added all the necessary network extensions. Despite this, we decided to submit the app to the App Store. It’s been five days now, and the app is still 'Waiting for Review.' Could anyone share their experience deploying and working on an iOS version of a VPN app? I’d really appreciate your insights!
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91
Mar ’25
SSH app
Hello. I would like to develop an application that sends SSH commands via my phone to the server. I know that applications of this type exist, but they are not suitable for my use as a blind person who uses a screen reader. I hope you can help me find libraries that will assist me in development, or ready-made, open-source projects that I can develop and modify if necessary. Thank you in advance.
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41
Mar ’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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95
May ’25
Do watchOS apps support IP request communication within a local area network?
As a third-party application on Apple Watch, can it be located in the same LAN httpServer? Currently, when testing to initiate an http request in the LAN, the connection timeout is returned, code: -1001 self.customSession.request("http://10.15.48.191:9000/hello").response { response in switch response.result { case .success(let data): dlog("✅ 请求成功,收到数据:") if let html = String(data: data ?? Data(), encoding: .utf8) { dlog(html) } case .failure(let error): dlog("❌ 请求失败:\(error.localizedDescription)") } } 执行后报错 Task <B71BE820-FD0E-4880-A6DD-1F8F6EAF98B0>.<1> finished with error [-1001] Error Domain=NSURLErrorDomain Code=-1001 "请求超时。" UserInfo={_kCFStreamErrorCodeKey=-2102, _NSURLErrorFailingURLSessionTaskErrorKey=LocalDataTask <B71BE820-FD0E-4880-A6DD-1F8F6EAF98B0>.<1>, _NSURLErrorRelatedURLSessionTaskErrorKey=( "LocalDataTask <B71BE820-FD0E-4880-A6DD-1F8F6EAF98B0>.<1>", "LocalDataPDTask <B71BE820-FD0E-4880-A6DD-1F8F6EAF98B0>.<1>", "LocalDataTask <B71BE820-FD0E-4880-A6DD-1F8F6EAF98B0>.<1>" ), NSLocalizedDescription=请求超时。, _kCFStreamErrorDomainKey=4, NSErrorFailingURLStringKey=http://10.15.48.191:9000/hello, NSErrorFailingURLKey=http://10.15.48.191:9000/hello}
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83
May ’25
Custom IPSec IKEv2 with Packet Tunnel Provider Extension on iOS
We’re looking to implement a custom IPSec IKEv2 VPN using the Packet Tunnel Provider network extension on iOS because we need to add extra information to EAP, which the built-in IKEv2 VPN configuration does not support. Is it possible to handle the full IKEv2 negotiation and IPSec tunneling within the Packet Tunnel Provider extension? Or are there limitations that would prevent implementing a full IKEv2 stack this way? Any insights or alternative approaches would be appreciated. Thanks!
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77
Mar ’25
Unable to Find Local Network Devices in Simulator – Permission Issue on M4 Mac, macOS 15.5, Xcode 16.1
Hello, I'm running into an issue while developing an iOS app that requires local network access. I’m using the latest MacBook Air M4 with macOS sequoia 15.5 and Xcode 16.1. In the iOS Simulator, my app fails to discover devices connected to the same local network. I’ve already added the necessary key to the Info.plist: NSLocalNetworkUsageDescription This app needs access to local network devices. When I run the app on a real device and M2 Chip Macbook's simulators, it works fine for local network permission as expected. However, in the M4 Chip Macbook's Simulator: The app can’t find any devices on the local network Bonjour/mDNS seems not to be working as well I’ve tried the following without success: Restarting Simulator and Mac Resetting network settings in Simulator Confirming app permissions under System Settings > Privacy & Security Has anyone else encountered this issue with the new Xcode/macOS combo? Is local network access just broken in the Simulator for now, or is there a workaround? Thanks in advance!
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159
May ’25