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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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Could not delete cookies on IOS18
Hello, I have encountered an issue with an iPhone 15PM with iOS 18.5. The NSHTTPCookieStorage failed to clear cookies, after clearing them, I was still able to retrieve them. However, on the same system NSHTTPCookie *cookie; NSHTTPCookieStorage *storage = [NSHTTPCookieStorage sharedHTTPCookieStorage]; for (cookie in [storage cookies]) { [storage deleteCookie:cookie]; } NSArray *cookies = [[NSHTTPCookieStorage sharedHTTPCookieStorage] cookiesForURL:[[self url] absoluteURL]]; // still able to get cookies,why???
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111
Jun ’25
Way to suppress local network access prompt in sequoia for Unix Domain Socket from swift
Hello, We have a SwiftUI-based application that runs as a LaunchAgent and communicates with other internal components using Unix domain sockets (UDS). On Sequoia (macOS virtualized environment), when installing the app, we encounter the Local Network Privacy Alert, asking: "Allow [AppName] to find and connect to devices on the local network?" We are not using any actual network communication — only interprocess communication via UDS. Is there a way to prevent this system prompt, either through MDM configuration or by adjusting our socket-related implementation? Here's a brief look at our Swift/NIO usage: class ClientHandler: ChannelInboundHandler { ... public func channelRead(context: ChannelHandlerContext, data: NIOAny) { ... } ... } // init bootstrap. var bootstrap: ClientBootstrap { return ClientBootstrap(group: group) // Also tried to remove the .so_reuseaddr, the prompt was still there. .channelOption(ChannelOptions.socketOption(.so_reuseaddr), value: 1) .channelInitializer { channel in // Add ChannelInboundHandler reader. channel.pipeline.addHandler(ClientHandler()) } } // connect to the UDS. self.bootstrap.connect(unixDomainSocketPath: self.path).whenSuccess { (channel) in .. self.channel = channel } ... ... // Send some data. self.channel?.writeAndFlush(buffer).wait() Any guidance would be greatly appreciated.
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135
May ’25
in-addr.arpa default search domains
Hi, I observed some unexpected behavior and hope that someone can enlighten me as to what this is about: mDNSResponder prepends IP / network based default search domains that are checked before any other search domain. E.g. 0.1.168.192.in-addr.arpa. would be used for an interface with an address in the the 192.168.1.0/24 subnet. This is done for any configured non-link-local IP address. I tried to find any mention of an approach like this in RFCs but couldn't spot anything. Please note that this is indeed a search domain and different from reverse-DNS lookups. Example output of tcpdump for ping devtest: 10:02:13.850802 IP (tos 0x0, ttl 64, id 43461, offset 0, flags [none], proto UDP (17), length 92) 192.168.1.2.52319 > 192.168.1.1.53: 54890+ [1au] A? devtest.0.1.168.192.in-addr.arpa. (64) I was able to identify the code that adds those default IP subnet based search domains but failed to spot any indication as to what this is about: https://github.com/apple-oss-distributions/mDNSResponder/blob/d5029b5/mDNSMacOSX/mDNSMacOSX.c#L4171-L4211 Does anyone here have an ideas as to what this might be about?
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771
Apr ’25
Crash heppen when i set to false to the usesClassicLoadingMode in URLSessionConfiguration
when i set the flag false to the usesClassicLoadingMode, then the application is getting crashed Ex: let config = URLSessionConfiguration.default if #available(iOS 18.4, *) { config.usesClassicLoadingMode = false } Crash log : *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[__NSCFBoolean objectForKeyedSubscript:]: unrecognized selector sent to instance 0x1f655c390' *** First throw call stack: (0x188ae52ec 0x185f69a7c 0x188b4f67c 0x1889fcb84 0x1889fc4f0 0x191393bc8 0x1889ec8a0 0x1889ec6e4 0x191393ad0 0x191344dac 0x191344b58 0x107cfa064 0x107ce36d0 0x191343fcc 0x1891b3b18 0x1892dae58 0x189235c60 0x18921e270 0x18921d77c 0x18921a8ac 0x107ce0584 0x107cfa064 0x107ce891c 0x107ce95d8 0x107ceabcc 0x107cf5894 0x107cf4eb0 0x212f51660 0x212f4e9f8) terminating due to uncaught exception of type NSException
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154
Apr ’25
[iPadOS 26] EACCES (Permission Denied) on UDP Broadcast despite Multicast Networking Entitlement
My application (using a nested framework for networking) was working correctly on iPadOS 18, but failed to perform a UDP broadcast operation after upgrading the device to iPadOS 26. The low-level console logs consistently show a "Permission denied" error. Symptoms & Error Message: When attempting to send a UDP broadcast packet using NWConnection (or a similar low-level socket call within the framework), the connection fails immediately with the following error logged in the console: nw_socket_service_writes_block_invoke [C2:1] sendmsg(fd 6, 124 bytes) [13: Permission denied] (Error code 13 corresponds to EACCES). Verification Steps (What I have checked): Multicast Networking Entitlement is Approved and Applied: The necessary entitlement (com.apple.developer.networking.multicast) was granted by Apple. The Provisioning Profile used for signing the Host App Target has been regenerated and explicitly includes "Multicast Networking" capability (see attached screenshot). I confirmed that Entitlements cannot be added directly to the Framework Target, only the Host App Target, which is the expected behavior. Local Network Privacy is Configured: The Host App's Info.plist contains the NSLocalNetworkUsageDescription key with a clear usage string. Crucially, the Local Network Access alert does not reliably appear when the Broadcast function is first called (despite a full reinstall after OS upgrade). Even when Local Network Access is manually enabled in Settings, the Broadcast still fails with EACCES. Code Implementation: The Broadcast is attempted using NWConnection to the host 255.255.255.255 on a specific port. Request: Since all required entitlements and profiles are correct, and the failure is a low-level EACCES on a newly updated OS version, I suspect this may be a regression bug in the iPadOS 26 security sandbox when validating the Multicast Networking Entitlement against a low-level socket call (like sendmsg). Has anyone else encountered this specific Permission denied error on iPadOS 26 with a valid Multicast Entitlement, and is there a known workaround aside from switching to mDNS/Bonjour?
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218
Oct ’25
NWPathMonitor Reports Unexpected satisfied→unsatisfied→satisfied Sequence After WiFi Re-enablement
I am developing an iOS application using NWPathMonitor for network connectivity monitoring. We discovered a reproducible issue where disabling and re-enabling WiFi triggers an unexpected network status sequence. ENVIRONMENT: iOS Version: 17.x Device: iPhone (various models tested) Network Framework: NWPathMonitor from iOS Network framework STEPS TO REPRODUCE: Device connected to WiFi normally Disable WiFi via Settings or Control Center Re-enable WiFi via Settings or Control Center EXPECTED BEHAVIOR: WiFi reconnects and NWPathMonitor reports stable satisfied status ACTUAL BEHAVIOR: T+0s: WiFi re-enables, NWPathMonitor reports path.status = .satisfied T+8s: NWPathMonitor unexpectedly reports path.status = .unsatisfied with unsatisfiedReason = .notAvailable T+9-10s: NWPathMonitor reports path.status = .satisfied again Connection becomes stable afterward NETWORK PATH TIMELINE: T+0s: satisfied (IPv4: true, DNS: false) T+140ms: satisfied (IPv4: true, DNS: true) T+8.0s: unsatisfied (reason: notAvailable, no interfaces available) T+10.0s: satisfied (IPv4: true, DNS: true) KEY OBSERVATIONS: Timing consistency: unsatisfied event always occurs ~8 seconds after reconnection resolution: "Reset Network Settings" eliminates this behavior TECHNICAL QUESTIONS: What causes the 8-second delayed unsatisfied status after WiFi re-enablement? Is this expected behavior that applications should handle? Why does reset network setting in iPhone fix this issue?
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110
Jul ’25
URLSession not working on iOS26/Xcode26
Hi, I’m trying out my app with Xcode 26, running on an iOS 26 simulator. I'm having issues with URLSessions, it crashes when I set the URLSessionConfiguration to default, and if I don’t use the URLSessionConfiguration, it crashes if I use URLSession.shared. When running in a real device, it doesn't crash, but any network request will hang and time out after a while. Is it a known issue in the latest beta versions?
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264
Jun ’25
NetworkFramework and UDP Broadcast Mode (2025)
So it seems the NetworkFramework is still not able to support Broastcast Mode am I correct? As soon as I switch broadcast mode to On in my game I receive console messages instead of receiving data. nw_path_evaluator_create_flow_inner failed NECP_CLIENT_ACTION_ADD_FLOW (null) evaluator parameters: udp, definite, server, attribution: developer, reuse local address, context: Default Network Context (private), proc: 2702288D-96FB-37DD-8610-A68CC526EA0F, local address: 0.0.0.0:20778 nw_path_evaluator_create_flow_inner NECP_CLIENT_ACTION_ADD_FLOW 1FB68D7E-7C9B-47B2-B6AC-E5710CD9C9CD [17: File exists] nw_endpoint_flow_setup_channel [C2 192.168.178.221:52716 initial channel-flow (satisfied (Path is satisfied), interface: en0[802.11], ipv4, ipv6, dns, uses wifi)] failed to request add nexus flow nw_endpoint_flow_failed_with_error [C2 192.168.178.221:52716 initial channel-flow (satisfied (Path is satisfied), interface: en0[802.11], ipv4, ipv6, dns, uses wifi)] already failing, returning nw_endpoint_handler_create_from_protocol_listener [C2 192.168.178.221:52716 failed channel-flow (satisfied (Path is satisfied), interface: en0[802.11], ipv4, ipv6, dns, uses wifi)] nw_endpoint_flow_pre_attach_protocols nw_connection_create_from_protocol_on_nw_queue [C2] Failed to create connection from listener nw_ip_channel_inbox_handle_new_flow nw_connection_create_from_protocol_on_nw_queue failed I won't be able to receive data which is a real shame, so I guess I am stuck with the lower level code: // Enable broadcast var enableBroadcast: Int32 = 1 if setsockopt(socketDescriptor, SOL_SOCKET, SO_BROADCAST, &enableBroadcast, socklen_t(MemoryLayout<Int32>.size)) == -1 { let errorMessage = String(cString: strerror(errno)) throw UDPSocketError.cannotEnableBroadcast(errorMessage) }
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147
Apr ’25
Real-time audio application on locked device
I would like to inquire about the feasibility of developing an iOS application with the following requirements: The app must support real-time audio communication based on UDP. It needs to maintain a TCP signaling connection, even when the device is locked. The app will run only on selected devices within a controlled (closed) environment, such as company-managed iPads or iPhones. Could you please clarify the following: Is it technically possible to maintain an active TCP connection when the device is locked? What are the current iOS restrictions or limitations for background execution, particularly related to networking and audio? Are there any recommended APIs or frameworks (such as VoIP, PushKit, or Background Modes) suitable for this type of application?
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190
Jun ’25
NEFilterDataProvider Filtering Traffic to 127.0.0.1 Breaks Maven Build in IntelliJ IDEA
When filtering traffic to localhost (127.0.0.1), it causes Maven repository synchronization to fail in IntelliJ IDEA. However, Maven works correctly when local traffic is not filtered. I will provide a minimal code reproduction below. - (void)startFilterWithCompletionHandler:(void (^)(NSError *error))completionHandler { // Add code to initialize the filter NSMutableArray *rules = [NSMutableArray array]; NENetworkRule * rule = [[NENetworkRule alloc] initWithRemoteNetwork:nil remotePrefix:0 localNetwork:nil localPrefix:0 protocol:NENetworkRuleProtocolTCP direction:NETrafficDirectionAny]; [rules addObject:[[NEFilterRule alloc]initWithNetworkRule:rule action:NEFilterActionFilterData]]; rule = [[NENetworkRule alloc] initWithRemoteNetwork:nil remotePrefix:0 localNetwork:nil localPrefix:0 protocol:NENetworkRuleProtocolUDP direction:NETrafficDirectionAny]; [rules addObject:[[NEFilterRule alloc]initWithNetworkRule:rule action:NEFilterActionFilterData]]; NWHostEndpoint *hostEndpointIpv4 = [NWHostEndpoint endpointWithHostname:@"127.0.0.1" port:@"0"]; NENetworkRule *localHostRuleIpv4 = [[NENetworkRule alloc] initWithRemoteNetwork:hostEndpointIpv4 remotePrefix:32 localNetwork:hostEndpointIpv4 localPrefix:32 protocol:NENetworkRuleProtocolAny direction:NETrafficDirectionAny]; [rules addObject:[[NEFilterRule alloc]initWithNetworkRule:localHostRuleIpv4 action:NEFilterActionFilterData]]; NEFilterSettings *filterSetting = [[NEFilterSettings alloc] initWithRules:rules defaultAction:NEFilterActionAllow]; [self applySettings:filterSetting completionHandler:^(NSError * _Nullable error) { if (error) { NSLog(@"Failed to apply filter settring: %@", error.localizedDescription); } completionHandler(error); }]; } Maven Sync error: System Log: 默认 17:35:13.184509+0800 kernel cfil_inp_log:6179 <CFIL: outbound TCP data dropped for pre-existing un-filtered flow>: [41046 idea] <TCP out so 3bb6402f58a82e37 - flags 0x800840 0x80> lport 63166 fport 29735 laddr 127.0.0.1 faddr 127.0.0.1 默认 17:35:13.184510+0800 kernel cfil_inp_log:6179 <CFIL: outbound TCP data dropped for pre-existing un-filtered flow>: [41046 idea] <TCP out so d6dde374c8cb613b - flags 0x800840 0x80> lport 63165 fport 29735 laddr 127.0.0.1 faddr 127.0.0.1 默认 17:35:13.529546+0800 kernel cfil_inp_log:6179 <CFIL: outbound TCP data dropped for pre-existing un-filtered flow>: [41046 idea] <TCP out so cc915e74ba29f8cb - flags 0x800840 0x80> lport 63169 fport 39066 laddr 127.0.0.1 faddr 127.0.0.1 默认 17:35:13.529546+0800 kernel cfil_inp_log:6179 <CFIL: outbound TCP data dropped for pre-existing un-filtered flow>: [41046 idea] <TCP out so 2e15c3e54ebcc45 - flags 0x800840 0x80> lport 63168 fport 39066 laddr 127.0.0.1 faddr 127.0.0.1 默认 17:35:14.046094+0800 kernel cfil_inp_log:6179 <CFIL: outbound TCP data dropped for pre-existing un-filtered flow>: [41046 idea] <TCP out so 71f6d3a53472131f - flags 0x800840 0x80> lport 63172 fport 53241 laddr 127.0.0.1 faddr 127.0.0.1 默认 17:35:14.046145+0800 kernel cfil_inp_log:6179 <CFIL: outbound TCP data dropped for pre-existing un-filtered flow>: [41046 idea] <TCP out so c88a367c9717185b - flags 0x800840 0x80> lport 63171 fport 53241 laddr 127.0.0.1 faddr 127.0.0.1 Environment Details: Operating System: macOS 15.5 (Sequoia) IDE: IntelliJ IDEA 2025.1 Relevant Technology: NEFilterDataProvider (Network Extension) I have found reports of similar problems online: https://discussionschinese.apple.com/thread/255270330?sortBy=rank https://blog.csdn.net/weixin_42339552/article/details/137402307 They all seem to be caused by network extension。
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118
Oct ’25
How to Keep Cellular Data Active While Connected to a Local Hotspot for File Transfer?
Hi all, I’m developing a companion iOS app that connects to a device-created Wi-Fi hotspot to transfer videos or other files WebSocket. The challenge is: once the iPhone connects to this hotspot, it loses internet access because iOS routes all traffic through Wi-Fi. However, I’d like to keep the iPhone’s cellular data active and usable while staying connected to the local hotspot — so the app can access cloud APIs, or the user can continue using other apps that require internet access. I understand that iOS prioritizes Wi-Fi over cellular, but are there any supported workarounds or patterns (e.g., MFi programs, local-only Wi-Fi access, NEHotspotConfiguration behavior, etc.) that : • Using Wi-Fi only for local communication; • cellular to remain active for internet access. Any insights or Apple-recommended best practices would be greatly appreciated — especially any official references regarding MFi Accessory setup or NEHotspotConfiguration behavior in this context. Thanks in !
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109
Jun ’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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62
Jun ’25
Can't find server for API Endpoint that works.
Hi, I am making a AI-Powered app that makes api requests to the openai API. However, for security, I set up a vercel backend that handles the API calls securely, while my frontend makes a call to my vercel-hosted https endpoint. Interestingly, whenever I try to make that call on my device, an iPhone, I get this error: Task <91AE4DE0-2845-4348-89B4-D3DD1CF51B65>.<10> finished with error [-1003] Error Domain=NSURLErrorDomain Code=-1003 "A server with the specified hostname could not be found." UserInfo={_kCFStreamErrorCodeKey=-72000, NSUnderlyingError=0x1435783f0 {Error Domain=kCFErrorDomainCFNetwork Code=-1003 "(null)" UserInfo={_kCFStreamErrorDomainKey=10, _kCFStreamErrorCodeKey=-72000, _NSURLErrorNWResolutionReportKey=Resolved 0 endpoints in 3ms using unknown from query, _NSURLErrorNWPathKey=satisfied (Path is satisfied), interface: pdp_ip0[lte], ipv4, ipv6, dns, expensive, uses cell}}, _NSURLErrorFailingURLSessionTaskErrorKey=LocalDataTask <91AE4DE0-2845-4348-89B4-D3DD1CF51B65>.<10>, _NSURLErrorRelatedURLSessionTaskErrorKey=( "LocalDataTask <91AE4DE0-2845-4348-89B4-D3DD1CF51B65>.<10>" ), NSLocalizedDescription=A server with the specified hostname could not be found., NSErrorFailingURLStringKey=https://[my endpoint], NSErrorFailingURLKey=https://[my endpoint], _kCFStreamErrorDomainKey=10} I'm completely stuck because when I directly make https requests to other api's like openai's endpoint, without the proxy, it finds the server completely fine. Running my endpoint on terminal with curl also works as intended, as I see api key usages. But for some reason, on my project, it does not work. I've looked through almost every single post I could find online, but a lot all of the solutions are outdated and unhelpful. I'm willing to schedule a call, meeting, whatever to resolve this issue and get help more in depth as well.
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153
Jun ’25
New developer question - exporting Apple Watch data to central server
This is probably a basic question but I wanted to ask your advice for the best way to take consenting users' Watch data from Apple Health Kit and send it to our central server? One idea we had was to create an iOS app that gets the data from Apple's Health SDK on the phone and sends it to our server. Would appreciate any help here, thank you.
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72
Jun ’25
PF rules issue on MacOS 15
Hey! We are investigating a problem pf rules being ignored by some processes. Despite blocking all traffic, some outgoing unicast packets can be seen in tcpdump. Issue is present in MacOS 15.0.0 - 15.3.1 (Newest at the time of writing). I tested MacOS 14.7.4 and pf rules there behaved as expected. Steps to reproduce the issue: $ cat pf.conf block all $ sudo pfctl -e -F all -f ./pf.conf Password: pfctl: Use of -f option, could result in flushing of rules present in the main ruleset added by the system at startup. See /etc/pf.conf for further details. No ALTQ support in kernel ALTQ related functions disabled rules cleared nat cleared dummynet cleared 0 tables deleted. 196 states cleared source tracking entries cleared pf: statistics cleared pf: interface flags reset pfctl: pf already enabled After executing these commands MacOS 14 will block all outgoing unicast traffic, and on MacOS 15 data can be sent to arbitrary addresses: $ ifconfig en0 en0: flags=8863<UP,BROADCAST,SMART,RUNNING,SIMPLEX,MULTICAST> mtu 1500 options=6460<TSO4,TSO6,CHANNEL_IO,PARTIAL_CSUM,ZEROINVERT_CSUM> ether b6:5e:a5:c5:1e:db inet6 fe80::1090:9c8:4325:329a%en0 prefixlen 64 secured scopeid 0xe inet 192.168.50.144 netmask 0xffffff00 broadcast 192.168.50.255 nd6 options=201<PERFORMNUD,DAD> media: autoselect status: active $ sudo tcpdump -k A -i any -n src 192.168.50.144 tcpdump: data link type PKTAP tcpdump: verbose output suppressed, use -v[v]... for full protocol decode listening on any, link-type PKTAP (Apple DLT_PKTAP), snapshot length 524288 bytes 12:05:12.673472 (en0, proc com.apple.geod:1286:, svc BE, out, ch, flowid 0x0, ttag 0x0, dlt 0x1, cmpgc 0x0) IP 192.168.50.144.52012 > 17.253.15.196.443: Flags [P.], seq 1888882378:1888882402, ack 3554898220, win 2048, options [nop,nop,TS val 2752050055 ecr 1291585385], length 24 12:05:13.793937 (en0, proc com.apple.WebKit:974:, eproc Safari:804:, svc BE, out, ch, flowid 0x0, ttag 0x0, dlt 0x1, cmpgc 0x0) IP 192.168.50.144.52024 > 3.65.102.105.443: Flags [P.], seq 2011312019:2011312073, ack 673002582, win 2048, options [nop,nop,TS val 777228223 ecr 484269939], length 54 Was there any change in the way pfctl is used or is this a bug? This issue affects negatively privacy features of our product.
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339
Mar ’25
Cellular only VPN app
I have a requirement to create a VPN app which only works on Cellular. But I'm facing an issue like when wifi is ON, OS is using wifi interface to route the traffic instead of cellular. I tried some ways like let cellularParams = NWParameters.udp cellularParams.requiredInterfaceType = .cellular But this is not working properly as expected. How can I manually bind to cellular interface in iOS?
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101
Jul ’25