I’m developing an app designed for hospital environments, where public internet access may not be available. The app includes two components: the main app and a Local Connectivity Extension. Both rely on persistent TCP socket connections to communicate with a local server. We’re observing a recurring issue where the extension’s socket becomes unresponsive every 1–3 hours, but only when the device is on the lock screen, even if the main app remains in the foreground. When the screen is not locked, the connection is stable and no disconnections occur. ❗ Issue Details: • What’s going on: The extension sends a keep-alive ping packet every second, and the server replies with a pong and a system time packet. • The bug: The server stops receiving keep alive packets from the extension.  • On the server, we detect about 30 second gap on the server, a gap that shows no packets were received by the extension. This was confirmed via server logs and Wireshark).  • On the extension, from our logs there was no gap in sending packets. From it’s perspective, all packets were sent with no error.  • Because no packet are being received by the server, no packets will be sent to the extension. Eventually the server closes the connection due to keep-alive timeout.  • FYI we log when the NEAppPushProvider subclass sleeps and it did NOT go to sleep while we were debugging. 🧾 Example Logs: Extension log: 2025-03-24 18:34:48.808 sendKeepAliveRequest() 2025-03-24 18:34:49.717 sendKeepAliveRequest() 2025-03-24 18:34:50.692 sendKeepAliveRequest() ... // continuous sending of the ping packet to the server, no problems here 2025-03-24 18:35:55.063 sendKeepAliveRequest() 2025-03-24 18:35:55.063 keepAliveTimer IS TIME OUT... in CoreService. // this is triggered because we did not receive any packets from the server 2025-03-24 18:34:16.298 No keep-alive received for 16 seconds... connection ID=95b3... // this shows that there has been no packets being received by the extension ... 2025-03-24 18:34:30.298 Connection timed out on keep-alive. connection ID=95b3... // eventually closes due to no packets being received 2025-03-24 18:34:30.298 Remote Subsystem Disconnected {name=iPhone|Replica-Ext|...} ✅ Observations: • The extension process continues running and logging keep-alive attempts. • However, network traffic stops reaching the server, and no inbound packets are received by the extension. • It looks like the socket becomes silently suspended or frozen, without being properly closed or throwing an error. ❓Questions: • Do you know why this might happen within a Local Connectivity Extension, especially under foreground conditions and locked ? • Is there any known system behavior that might cause the socket to be suspended or blocked in this way after running for a few hours? Any insights or recommendations would be greatly appreciated. Thank you!

At WWDC 2015 Apple announced two major enhancements to the Network Extension framework: Network Extension providers — These are app extensions that let you insert your code at various points within the networking stack, including: Packet tunnels via NEPacketTunnelProvider App proxies via NEAppProxyProvider Content filters via NEFilterDataProvider and NEFilterControlProvider Hotspot Helper (NEHotspotHelper) — This allows you to create an app that assists the user in navigating a hotspot (a Wi-Fi network where the user must interact with the network in order to get access to the wider Internet). Originally, using any of these facilities required authorisation from Apple. Specifically, you had to apply for, and be granted access to, a managed capability. In Nov 2016 this policy changed for Network Extension providers. Any developer can now use the Network Extension provider capability like they would any other capability. There is one exception to this rule: Network Extension app push providers, introduced by iOS 14 in 2020, still requires that Apple authorise the use of a managed capability. To apply for that, follow the link in Local push connectivity. Also, the situation with Hotspot Helpers remains the same: Using a Hotspot Helper, requires that Apple authorise that use via a managed capability. To apply for that, follow the link in Hotspot helper. IMPORTANT Pay attention to this quote from the documentation: NEHotspotHelper is only useful for hotspot integration. There are both technical and business restrictions that prevent it from being used for other tasks, such as accessory integration or Wi-Fi based location. The rest of this document answers some frequently asked questions about the Nov 2016 change. #1 — Has there been any change to the OS itself? No, this change only affects the process by which you get the capabilities you need in order to use existing Network Extension framework facilities. Previously these were managed capabilities, meaning their use was authorised by Apple. Now, except for app push providers and Hotspot Helper, you can enable the necessary capabilities using Xcode’s Signing & Capabilities editor or the Developer website. IMPORTANT Some Network Extension providers have other restrictions on their use. For example, a content filter can only be used on a supervised device. These restrictions are unchanged. See TN3134 Network Extension provider deployment for the details. #2 — How exactly do I enable the Network Extension provider capability? In the Signing & Capabilities editor, add the Network Extensions capability and then check the box that matches the provider you’re creating. In the Certificates, Identifiers & Profiles section of the Developer website, when you add or edit an App ID, you’ll see a new capability listed, Network Extensions. Enable that capability in your App ID and then regenerate the provisioning profiles based on that App ID. A newly generated profile will include the com.apple.developer.networking.networkextension entitlement in its allowlist; this is an array with an entry for each of the supported Network Extension providers. To confirm that this is present, dump the profile as shown below. $ security cms -D -i NETest.mobileprovision … <plist version="1.0"> <dict> … <key>Entitlements</key> <dict> <key>com.apple.developer.networking.networkextension</key> <array> <string>packet-tunnel-provider</string> <string>content-filter-provider</string> <string>app-proxy-provider</string> … and so on … </array> … </dict> … </dict> </plist> #3 — I normally use Xcode’s Signing & Capabilities editor to manage my entitlements. Do I have to use the Developer website for this? No. Xcode 11 and later support this capability in the Signing & Capabilities tab of the target editor (r. 28568128 ). #4 — Can I still use Xcode’s “Automatically manage signing” option? Yes. Once you modify your App ID to add the Network Extension provider capability, Xcode’s automatic code signing support will include the entitlement in the allowlist of any profiles that it generates based on that App ID. #5 — What should I do if I previously applied for the Network Extension provider managed capability and I’m still waiting for a reply? Consider your current application cancelled, and use the new process described above. #6 — What should I do if I previously applied for the Hotspot Helper managed capability and I’m still waiting for a reply? Apple will continue to process Hotspot Helper managed capability requests and respond to you in due course. #7 — What if I previously applied for both Network Extension provider and Hotspot Helper managed capabilities? Apple will ignore your request for the Network Extension provider managed capability and process it as if you’d only asked for the Hotspot Helper managed capability. #8 — On the Mac, can Developer ID apps host Network Extension providers? Yes, but there are some caveats: This only works on macOS 10.15 or later. Your Network Extension provider must be packaged as a system extension, not an app extension. You must use the *-systemextension values for the Network Extension entitlement (com.apple.developer.networking.networkextension). For more on this, see Exporting a Developer ID Network Extension. #9 — After moving to the new process, my app no longer has access to the com.apple.managed.vpn.shared keychain access group. How can I regain that access? Access to this keychain access group requires another managed capability. If you need that, please open a DTS code-level support request and we’ll take things from there. IMPORTANT This capability is only necessary if your VPN supports configuration via a configuration profile and needs to access credentials from that profile (as discussed in the Profile Configuration section of the NETunnelProviderManager Reference). Many VPN apps don’t need this facility. If you were previously granted the Network Extension managed capability (via the process in place before Nov 2016), make sure you mention that; restoring your access to the com.apple.managed.vpn.shared keychain access group should be straightforward in that case. Share and Enjoy — Quinn “The Eskimo!” @ Developer Technical Support @ Apple let myEmail = "eskimo" + "1" + "@" + "apple.com" Revision History 2025-11-11 Removed the discussion of TSI assets because those are no longer a thing. 2025-09-12 Adopted the code-level support request terminology. Made other minor editorial changes. 2023-01-11 Added a discussion of Network Extension app push providers. Added a link to Exporting a Developer ID Network Extension. Added a link to TN3134. Made significant editorial changes. 2020-02-27 Fixed the formatting. Updated FAQ#3. Made minor editorial changes. 2020-02-16 Updated FAQ#8 to account for recent changes. Updated FAQ#3 to account for recent Xcode changes. Made other editorial changes. 2016-01-25 Added FAQ#9. 2016-01-6 Added FAQ#8. 2016-11-11 Added FAQ#5, FAQ#6 and FAQ#7. 2016-11-11 First posted.

We have a NEFilterDataProvider extension that intercepts all TCP and UDP IPv4/6 traffic. At times just after wakeup from sleep, it causes internet access issues, such as showing "This site can't be reached" when opening websites. The traffic is not being dropped by the extension. According to the logs, the connection is being closed after approximately 4 minutes. During the issue, the flow logs are as follows: Flow 515129771 is connecting New flow: NEFlow type = stream, app = com.google.Chrome.helper... Detaching, ref count = 2 (logged after ~4 minutes) Sending close, how = 2 Removing from group 2, ref count = 2 Destroying, app tx 0, tunnel tx 0, tunnel rx 0 Closing reads, not closed by plugin Closing writes, not sending close Any suggestions on the possible cause and how to further debug it?

Continuing with my investigations of several issues that we have been noticing in our testing of the JDK with macosx 15.x, I have now narrowed down at least 2 separate problems for which I need help. For a quick background, starting with macosx 15.x several networking related tests within the JDK have started failing in very odd and hard to debug ways in our internal lab. Reading through the macos docs and with help from others in these forums, I have come to understand that a lot of these failures are to do with the new restrictions that have been placed for "Local Network" operations. I have read through https://developer.apple.com/documentation/technotes/tn3179-understanding-local-network-privacy and I think I understand the necessary background about these restrictions. There's more than one issue in this area that I will need help with, so I'll split them out into separate topics in this forum. That above doc states: macOS 15.1 fixed a number of local network privacy bugs. If you encounter local network privacy problems on macOS 15.0, retest on macOS 15.1 or later. We did have (and continue to have) 15.0 and 15.1 macos instances within our lab which are impacted by these changes. They too show several networking related failures. However, I have decided not to look into those systems and instead focus only on 15.3.1. People might see unexpected behavior in System Settings > Privacy & Security if they have multiple versions of the same app installed (FB15568200). This feedback assistant issue and several others linked in these documentations are inaccessible (even when I login with my existing account). I think it would be good to have some facility in the feedback assistant tool/site to make such issues visible (even if read-only) to be able to watch for updates to those issues. So now coming to the issue. Several of the networking tests in the JDK do mulicasting testing (through BSD sockets API) in order to test the Java SE multicasting socket API implementations. One repeated failure we have been seeing in our labs is an exception with the message "No route to host". It shows up as: Process id: 58700 ... java.net.NoRouteToHostException: No route to host at java.base/sun.nio.ch.DatagramChannelImpl.send0(Native Method) at java.base/sun.nio.ch.DatagramChannelImpl.sendFromNativeBuffer(DatagramChannelImpl.java:914) at java.base/sun.nio.ch.DatagramChannelImpl.send(DatagramChannelImpl.java:871) at java.base/sun.nio.ch.DatagramChannelImpl.send(DatagramChannelImpl.java:798) at java.base/sun.nio.ch.DatagramChannelImpl.blockingSend(DatagramChannelImpl.java:857) at java.base/sun.nio.ch.DatagramSocketAdaptor.send(DatagramSocketAdaptor.java:178) at java.base/java.net.DatagramSocket.send(DatagramSocket.java:593) (this is just one example stacktrace from java program) That "send0" is implemented by the JDK by invoking the sendto() system call. In this case, the sendto() is returning a EHOSTUNREACH error which is what is then propagated to the application. The forum text editor doesn't allow me to post long text, so I'm going to post the rest of this investigation and logs as a reply.

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.

Our app receives real-time GPS and aircraft data from devices via UDP broadcast and/or multicast on a WiFi network created by the device. We have identified that the iPhone or iPad will just stop receiving UDP broadcast/multicast data for an interval of time. In general, it appears after roughly every 128KB of data is received. In the attached screenshot from Xcode instruments, you can see the data reception alternating on/off. We have verified with Wireshark that the data is still flowing during that entire time period. And by tracking bytes received the app ultimately receives about 55% of the bytes, which tracks with the Network graph. We have used different approaches to the network code, including GCDAsyncUdpSocket, BSD Sockets, and the Network framework. We've tried it on background threads and the main thread. Tested it on iPads and iPhones. All produce the same result. The data is just never reaching the app code. Any insight on what may be temporarily disabling data reception?

I use eapolcfg in Apple's open source eap8021x repository to connect to the enterprise network. 1.https://github.com/gfleury/eap8021x-debug https://opensource.apple.com/source/eap8021x/eap8021x-304.100.1/ Our enterprise network authentication is PEAP. So far, I have created a profile using the following commands and have done the access. ./eapolcfg createProfile --authType PEAP --SSID myssid --securityType WPA2 --userDefinedName MyProfile ./eapolcfg setPasswordItem --password mypassword --name myname --SSID myssid ./eapolcfg startAuthentication --interface en0 --SSID myssid After I performed this series of operations, I passed BOOL success = [self.interface associateToEnterpriseNetwork:network identity:nil username:username password:password error:&amp;error]; Connection will pop up the following pop-up window, sometimes associateToEnterpriseNetwork will fail. I don't know what went wrong, is it that I missed some steps through the eapolcfg [tool?] This function also reports the following error：Error Domain=com.apple.coreWLAN.EAPOL.error Code=1 "(null)" Please answer my questions. Thank you very much

I have an iPhone app which relies heavily on TCP/IP communication in the local network. Therefore, the application starts a server socket and accepts incoming connections. This worked flawlessly for a long time and we had no problems with this. Problem In the last days however, we observed that for some iPhones with the server role other devices cannot connect to the server of our app. The server does not accept incoming connections on the devices IP address and the client times out. Environment Both iPhones (the server and the client) are in the same network with 192.168.1.0 address range and 255.255.255.0 subnet mask. The server has the IP 192.168.1.11 and the client has 192.168.1.22. This is a normal home WiFi network with no special firewall rules. Both devices have mobile data disabled and the "access local network" permission is granted. The server socket is bound to all interfaces (0.0.0.0). More technical symptoms When the server iPhone is in this faulty state, it seems like it somehow has two ip addresses: 192.168.2.123 and 192.168.1.11 The WiFi preferences show the (correct) .1.11 ip address. The Apps however see the (wrong) .2.123 ip address. I cannot explain where the other ip address comes from and why the device thinks it has this ip address. I've collected interface diagnosis information on a faulty iPhone and it listed the following interfaces and IPs: en0 -> 192.168.2.123 lo0 -> 127.0.0.1 pdp_ip0 (cellular) -> 192.0.0.2 pdp_ip1 to pdp_ip6 (cellular) -> -/- ipsec0 to ipsec6 (vpn) -> -/- llw0 (vpn) -> -/- awdl0 -> -/- anpi0 -> -/- ap1 -> -/- XHC0 -> -/- en1 and en2 (wired) -> -/- utun0 to utun2 (vpn) -> -/- The correct ip of the device is not listed anywhere in this list. A reboot helped to temporarily fix this problem. One user reported the same issue again a few hours later after a reboot. Switching off WiFi and reconnecting does not solve the problem. This issue occurred on several iPhones with the following specs: iOS Version 18.1.1, 18.3.1 iPhone 13 Pro, iPhone 13 Pro Max, iPhone 15 Pro The problem must be on the server side as the client can successfully connect to any other device in the same network. Question(s) Where does this second IP come from and why does the server not accept connections to either ip even though it is bound to 0.0.0.0? Are there any iOS system settings which could lead to this problem? (privacy setting, vpn, ...) What could be done to permanently fix this issue?

I see a lot of folks spend a lot of time trying to get Multipeer Connectivity to work for them. My experience is that the final result is often unsatisfactory. Instead, my medium-to-long term recommendation is to use Network framework instead. This post explains how you might move from Multipeer Connectivity to Network framework. If you have questions or comments, put them in a new thread. Place it in the App & System Services > Networking topic area and tag it with Multipeer Connectivity and Network framework. Share and Enjoy — Quinn “The Eskimo!” @ Developer Technical Support @ Apple let myEmail = "eskimo" + "1" + "@" + "apple.com" Moving from Multipeer Connectivity to Network Framework Multipeer Connectivity has a number of drawbacks: It has an opinionated networking model, where every participant in a session is a symmetric peer. Many apps work better with the traditional client/server model. It offers good latency but poor throughput. It doesn’t support flow control, aka back pressure, which severely constrains its utility for general-purpose networking. It includes a number of UI components that are effectively obsolete. It hasn’t evolved in recent years. For example, it relies on NSStream, which has been scheduled for deprecation as far as networking is concerned. It always enables peer-to-peer Wi-Fi, something that’s not required for many apps and can impact the performance of the network (see Enable peer-to-peer Wi-Fi, below, for more about this). Its security model requires the use of PKI — public key infrastructure, that is, digital identities and certificates — which are tricky to deploy in a peer-to-peer environment. It has some gnarly bugs. IMPORTANT Many folks use Multipeer Connectivity because they think it’s the only way to use peer-to-peer Wi-Fi. That’s not the case. Network framework has opt-in peer-to-peer Wi-Fi support. See Enable peer-to-peer Wi-Fi, below. If Multipeer Connectivity is not working well for you, consider moving to Network framework. This post explains how to do that in 13 easy steps (-: Plan for security Select a network architecture Create a peer identifier Choose a protocol to match your send mode Discover peers Design for privacy Configure your connections Manage a listener Manage a connection Send and receive reliable messages Send and receive best effort messages Start a stream Send a resource Finally, at the end of the post you’ll find two appendices: Final notes contains some general hints and tips. Symbol cross reference maps symbols in the Multipeer Connectivity framework to sections of this post. Consult it if you’re not sure where to start with a specific Multipeer Connectivity construct. Plan for security The first thing you need to think about is security. Multipeer Connectivity offers three security models, expressed as choices in the MCEncryptionPreference enum: .none for no security .optional for optional security .required for required security For required security each peer must have a digital identity. Optional security is largely pointless. It’s more complex than no security but doesn’t yield any benefits. So, in this post we’ll focus on the no security and required security models. Your security choice affects the network protocols you can use: QUIC is always secure. WebSocket, TCP, and UDP can be used with and without TLS security. QUIC security only supports PKI. TLS security supports both TLS-PKI and pre-shared key (PSK). You might find that TLS-PSK is easier to deploy in a peer-to-peer environment. To configure the security of the QUIC protocol: func quicParameters() -> NWParameters { let quic = NWProtocolQUIC.Options(alpn: ["MyAPLN"]) let sec = quic.securityProtocolOptions … configure `sec` here … return NWParameters(quic: quic) } To enable TLS over TCP: func tlsOverTCPParameters() -> NWParameters { let tcp = NWProtocolTCP.Options() let tls = NWProtocolTLS.Options() let sec = tls.securityProtocolOptions … configure `sec` here … return NWParameters(tls: tls, tcp: tcp) } To enable TLS over UDP, also known as DTLS: func dtlsOverUDPParameters() -> NWParameters { let udp = NWProtocolUDP.Options() let dtls = NWProtocolTLS.Options() let sec = dtls.securityProtocolOptions … configure `sec` here … return NWParameters(dtls: dtls, udp: udp) } To configure TLS with a local digital identity and custom server trust evaluation: func configureTLSPKI(sec: sec_protocol_options_t, identity: SecIdentity) { let secIdentity = sec_identity_create(identity)! sec_protocol_options_set_local_identity(sec, secIdentity) if disableServerTrustEvaluation { sec_protocol_options_set_verify_block(sec, { metadata, secTrust, completionHandler in let trust = sec_trust_copy_ref(secTrust).takeRetainedValue() … evaluate `trust` here … completionHandler(true) }, .main) } } To configure TLS with a pre-shared key: func configureTLSPSK(sec: sec_protocol_options_t, identity: Data, key: Data) { let identityDD = identity.withUnsafeBytes { DispatchData(bytes: $0) } let keyDD = identity.withUnsafeBytes { DispatchData(bytes: $0) } sec_protocol_options_add_pre_shared_key( sec, keyDD as dispatch_data_t, identityDD as dispatch_data_t ) sec_protocol_options_append_tls_ciphersuite( sec, tls_ciphersuite_t(rawValue: TLS_PSK_WITH_AES_128_GCM_SHA256)! ) } Select a network architecture Multipeer Connectivity uses a star network architecture. All peers are equal, and every peer is effectively connected to every peer. Many apps work better with the client/server model, where one peer acts on the server and all the others are clients. Network framework supports both models. To implement a client/server network architecture with Network framework: Designate one peer as the server and all the others as clients. On the server, use NWListener to listen for incoming connections. On each client, use NWConnection to made an outgoing connection to the server. To implement a star network architecture with Network framework: On each peer, start a listener. And also start a connection to each of the other peers. This is likely to generate a lot of redundant connections, as peer A connects to peer B and vice versa. You’ll need to a way to deduplicate those connections, which is the subject of the next section. IMPORTANT While the star network architecture is more likely to create redundant connections, the client/server network architecture can generate redundant connections as well. The advice in the next section applies to both architectures. Create a peer identifier Multipeer Connectivity uses MCPeerID to uniquely identify each peer. There’s nothing particularly magic about MCPeerID; it’s effectively a wrapper around a large random number. To identify each peer in Network framework, generate your own large random number. One good choice for a peer identifier is a locally generated UUID, created using the system UUID type. Some Multipeer Connectivity apps persist their local MCPeerID value, taking advantage of its NSSecureCoding support. You can do the same with a UUID, using either its string representation or its Codable support. IMPORTANT Before you decide to persist a peer identifier, think about the privacy implications. See Design for privacy below. Avoid having multiple connections between peers; that’s both wasteful and potentially confusing. Use your peer identifier to deduplicate connections. Deduplicating connections in a client/server network architecture is easy. Have each client check in with the server with its peer identifier. If the server already has a connection for that identifier, it can either close the old connection and keep the new connection, or vice versa. Deduplicating connections in a star network architecture is a bit trickier. One option is to have each peer send its peer identifier to the other peer and then the peer with the ‘best’ identifier wins. For example, imagine that peer A makes an outgoing connection to peer B while peer B is simultaneously making an outgoing connection to peer A. When a peer receives a peer identifier from a connection, it checks for a duplicate. If it finds one, it compares the peer identifiers and then chooses a connection to drop based on that comparison: if local peer identifier > remote peer identifier then drop outgoing connection else drop incoming connection end if So, peer A drops its incoming connection and peer B drops its outgoing connection. Et voilà! Choose a protocol to match your send mode Multipeer Connectivity offers two send modes, expressed as choices in the MCSessionSendDataMode enum: .reliable for reliable messages .unreliable for best effort messages Best effort is useful when sending latency-sensitive data, that is, data where retransmission is pointless because, by the retransmission arrives, the data will no longer be relevant. This is common in audio and video applications. In Network framework, the send mode is set by the connection’s protocol: A specific QUIC connection is either reliable or best effort. WebSocket and TCP are reliable. UDP is best effort. Start with a reliable connection. In many cases you can stop there, because you never need a best effort connection. If you’re not sure which reliable protocol to use, choose WebSocket. It has key advantages over other protocols: It supports both security models: none and required. Moreover, its required security model supports both TLS-PKI and TLS PSK. In contrast, QUIC only supports the required security model, and within that model it only supports TLS-PKI. It allows you to send messages over the connection. In contrast, TCP works in terms of bytes, meaning that you have to add your own framing. If you need a best effort connection, get started with a reliable connection and use that connection to set up a parallel best effort connection. For example, you might have an exchange like this: Peer A uses its reliable WebSocket connection to peer B to send a request for a parallel best effort UDP connection. Peer B receives that, opens a UDP listener, and sends the UDP listener’s port number back to peer A. Peer A opens its parallel UDP connection to that port on peer B. Note For step 3, get peer B’s IP address from the currentPath property of the reliable WebSocket connection. If you’re not sure which best effort protocol to use, use UDP. While it is possible to use QUIC in datagram mode, it has the same security complexities as QUIC in reliable mode. Discover peers Multipeer Connectivity has a types for advertising a peer’s session (MCAdvertiserAssistant) and a type for browsering for peer (MCNearbyServiceBrowser). In Network framework, configure the listener to advertise its service by setting the service property of NWListener: let listener: NWListener = … listener.service = .init(type: "_example._tcp") listener.serviceRegistrationUpdateHandler = { change in switch change { case .add(let endpoint): … update UI for the added listener endpoint … break case .remove(let endpoint): … update UI for the removed listener endpoint … break @unknown default: break } } listener.stateUpdateHandler = … handle state changes … listener.newConnectionHandler = … handle the new connection … listener.start(queue: .main) This example also shows how to use the serviceRegistrationUpdateHandler to update your UI to reflect changes in the listener. Note This example uses a service type of _example._tcp. See About service types, below, for more details on that. To browse for services, use NWBrowser: let browser = NWBrowser(for: .bonjour(type: "_example._tcp", domain: nil), using: .tcp) browser.browseResultsChangedHandler = { latestResults, _ in … update UI to show the latest results … } browser.stateUpdateHandler = … handle state changes … browser.start(queue: .main) This yields NWEndpoint values for each peer that it discovers. To connect to a given peer, create an NWConnection with that endpoint. About service types The examples in this post use _example._tcp for the service type. The first part, _example, is directly analogous to the serviceType value you supply when creating MCAdvertiserAssistant and MCNearbyServiceBrowser objects. The second part is either _tcp or _udp depending on the underlying transport protocol. For TCP and WebSocket, use _tcp. For UDP and QUIC, use _udp. Service types are described in RFC 6335. If you deploy an app that uses a new service type, register that service type with IANA. Discovery UI Multipeer Connectivity also has UI components for advertising (MCNearbyServiceAdvertiser) and browsing (MCBrowserViewController). There’s no direct equivalent to this in Network framework. Instead, use your preferred UI framework to create a UI that best suits your requirements. Note If you’re targeting Apple TV, check out the DeviceDiscoveryUI framework. Discovery TXT records The Bonjour service discovery protocol used by Network framework supports TXT records. Using these, a listener can associate metadata with its service and a browser can get that metadata for each discovered service. To advertise a TXT record with your listener, include it it the service property value: let listener: NWListener = … let peerID: UUID = … var txtRecord = NWTXTRecord() txtRecord["peerID"] = peerID.uuidString listener.service = .init(type: "_example._tcp", txtRecord: txtRecord.data) To browse for services and their associated TXT records, use the .bonjourWithTXTRecord(…) descriptor: let browser = NWBrowser(for: .bonjourWithTXTRecord(type: "_example._tcp", domain: nil), using: .tcp) browser.browseResultsChangedHandler = { latestResults, _ in for result in latestResults { guard case .bonjour(let txtRecord) = result.metadata, let peerID = txtRecord["peerID"] else { continue } // … examine `result` and `peerID` … _ = peerID } } This example includes the peer identifier in the TXT record with the goal of reducing the number of duplicate connections, but that’s just one potential use for TXT records. Design for privacy This section lists some privacy topics to consider as you implement your app. Obviously this isn’t an exhaustive list. For general advice on this topic, see Protecting the User’s Privacy. There can be no privacy without security. If you didn’t opt in to security with Multipeer Connectivity because you didn’t want to deal with PKI, consider the TLS-PSK options offered by Network framework. For more on this topic, see Plan for security. When you advertise a service, the default behaviour is to use the user-assigned device name as the service name. To override that, create a service with a custom name: let listener: NWListener = … let name: String = … listener.service = .init(name: name, type: "_example._tcp") It’s not uncommon for folks to use the peer identifier as the service name. Whether that’s a good option depends on the user experience of your product: Some products present a list of remote peers and have the user choose from that list. In that case it’s best to stick with the user-assigned device name, because that’s what the user will recognise. Some products automatically connect to services as they discover them. In that case it’s fine to use the peer identifier as the service name, because the user won’t see it anyway. If you stick with the user-assigned device name, consider advertising the peer identifier in your TXT record. See Discovery TXT records. IMPORTANT Using a peer identifier in your service name or TXT record is a heuristic to reduce the number of duplicate connections. Don’t rely on it for correctness. Rather, deduplicate connections using the process described in Create a peer identifier. There are good reasons to persist your peer identifier, but doing so isn’t great for privacy. Persisting the identifier allows for tracking of your service over time and between networks. Consider whether you need a persistent peer identifier at all. If you do, consider whether it makes sense to rotate it over time. A persistent peer identifier is especially worrying if you use it as your service name or put it in your TXT record. Configure your connections Multipeer Connectivity’s symmetric architecture means that it uses a single type, MCSession, to manage the connections to all peers. In Network framework, that role is fulfilled by two types: NWListener to listen for incoming connections. NWConnection to make outgoing connections. Both types require you to supply an NWParameters value that specifies the network protocol and options to use. In addition, when creating an NWConnection you pass in an NWEndpoint to tell it the service to connect to. For example, here’s how to configure a very simple listener for TCP: let parameters = NWParameters.tcp let listener = try NWListener(using: parameters) … continue setting up the listener … And here’s how you might configure an outgoing TCP connection: let parameters = NWParameters.tcp let endpoint = NWEndpoint.hostPort(host: "example.com", port: 80) let connection = NWConnection.init(to: endpoint, using: parameters) … continue setting up the connection … NWParameters has properties to control exactly what protocol to use and what options to use with those protocols. To work with QUIC connections, use code like that shown in the quicParameters() example from the Security section earlier in this post. To work with TCP connections, use the NWParameters.tcp property as shown above. To enable TLS on your TCP connections, use code like that shown in the tlsOverTCPParameters() example from the Security section earlier in this post. To work with WebSocket connections, insert it into the application protocols array: let parameters = NWParameters.tcp let ws = NWProtocolWebSocket.Options(.version13) parameters.defaultProtocolStack.applicationProtocols.insert(ws, at: 0) To enable TLS on your WebSocket connections, use code like that shown in the tlsOverTCPParameters() example to create your base parameters and then add the WebSocket application protocol to that. To work with UDP connections, use the NWParameters.udp property: let parameters = NWParameters.udp To enable TLS on your UDP connections, use code like that shown in the dtlsOverUDPParameters() example from the Security section earlier in this post. Enable peer-to-peer Wi-Fi By default, Network framework doesn’t use peer-to-peer Wi-Fi. To enable that, set the includePeerToPeer property on the parameters used to create your listener and connection objects. parameters.includePeerToPeer = true IMPORTANT Enabling peer-to-peer Wi-Fi can impact the performance of the network. Only opt into it if it’s a significant benefit to your app. If you enable peer-to-peer Wi-Fi, it’s critical to stop network operations as soon as you’re done with them. For example, if you’re browsing for services with peer-to-peer Wi-Fi enabled and the user picks a service, stop the browse operation immediately. Otherwise, the ongoing browse operation might affect the performance of your connection. Manage a listener In Network framework, use NWListener to listen for incoming connections: let parameters: NWParameters = .tcp … configure parameters … let listener = try NWListener(using: parameters) listener.service = … service details … listener.serviceRegistrationUpdateHandler = … handle service registration changes … listener.stateUpdateHandler = { newState in … handle state changes … } listener.newConnectionHandler = { newConnection in … handle the new connection … } listener.start(queue: .main) For details on how to set up parameters, see Configure your connections. For details on how to set up up service and serviceRegistrationUpdateHandler, see Discover peers. Network framework calls your state update handler when the listener changes state: let listener: NWListener = … listener.stateUpdateHandler = { newState in switch newState { case .setup: // The listener has not yet started. … case .waiting(let error): // The listener tried to start and failed. It might recover in the // future. … case .ready: // The listener is running. … case .failed(let error): // The listener tried to start and failed irrecoverably. … case .cancelled: // The listener was cancelled by you. … @unknown default: break } } Network framework calls your new connection handler when a client connects to it: var connections: [NWConnection] = [] let listener: NWListener = listener listener.newConnectionHandler = { newConnection in … configure the new connection … newConnection.start(queue: .main) connections.append(newConnection) } IMPORTANT Don’t forget to call start(queue:) on your connections. In Multipeer Connectivity, the session (MCSession) keeps track of all the peers you’re communicating with. With Network framework, that responsibility falls on you. This example uses a simple connections array for that purpose. In your app you may or may not need a more complex data structure. For example: In the client/server network architecture, the client only needs to manage the connections to a single peer, the server. On the other hand, the server must managed the connections to all client peers. In the star network architecture, every peer must maintain a listener and connections to each of the other peers. Understand UDP flows Network framework handles UDP using the same NWListener and NWConnection types as it uses for TCP. However, the underlying UDP protocol is not implemented in terms of listeners and connections. To resolve this, Network framework works in terms of UDP flows. A UDP flow is defined as a bidirectional sequence of UDP datagrams with the same 4 tuple (local IP address, local port, remote IP address, and remote port). In Network framework: Each NWConnection object manages a single UDP flow. If an NWListener receives a UDP datagram whose 4 tuple doesn’t match any known NWConnection, it creates a new NWConnection. Manage a connection In Network framework, use NWConnection to start an outgoing connection: var connections: [NWConnection] = [] let parameters: NWParameters = … let endpoint: NWEndpoint = … let connection = NWConnection(to: endpoint, using: parameters) connection.stateUpdateHandler = … handle state changes … connection.viabilityUpdateHandler = … handle viability changes … connection.pathUpdateHandler = … handle path changes … connection.betterPathUpdateHandler = … handle better path notifications … connection.start(queue: .main) connections.append(connection) As in the listener case, you’re responsible for keeping track of this connection. Each connection supports four different handlers. Of these, the state and viability update handlers are the most important. For information about the path update and better path handlers, see the NWConnection documentation. Network framework calls your state update handler when the connection changes state: let connection: NWConnection = … connection.stateUpdateHandler = { newState in switch newState { case .setup: // The connection has not yet started. … case .preparing: // The connection is starting. … case .waiting(let error): // The connection tried to start and failed. It might recover in the // future. … case .ready: // The connection is running. … case .failed(let error): // The connection tried to start and failed irrecoverably. … case .cancelled: // The connection was cancelled by you. … @unknown default: break } } If you a connection is in the .waiting(_:) state and you want to force an immediate retry, call the restart() method. Network framework calls your viability update handler when its viability changes: let connection: NWConnection = … connection.viabilityUpdateHandler = { isViable in … react to viability changes … } A connection becomes inviable when a network resource that it depends on is unavailable. A good example of this is the network interface that the connection is running over. If you have a connection running over Wi-Fi, and the user turns off Wi-Fi or moves out of range of their Wi-Fi network, any connection running over Wi-Fi becomes inviable. The inviable state is not necessarily permanent. To continue the above example, the user might re-enable Wi-Fi or move back into range of their Wi-Fi network. If the connection becomes viable again, Network framework calls your viability update handler with a true value. It’s a good idea to debounce the viability handler. If the connection becomes inviable, don’t close it down immediately. Rather, wait for a short while to see if it becomes viable again. If a connection has been inviable for a while, you get to choose as to how to respond. For example, you might close the connection down or inform the user. To close a connection, call the cancel() method. This gracefully disconnects the underlying network connection. To close a connection immediately, call the forceCancel() method. This is not something you should do as a matter of course, but it does make sense in exceptional circumstances. For example, if you’ve determined that the remote peer has gone deaf, it makes sense to cancel it in this way. Send and receive reliable messages In Multipeer Connectivity, a single session supports both reliable and best effort send modes. In Network framework, a connection is either reliable or best effort, depending on the underlying network protocol. The exact mechanism for sending a message depends on the underlying network protocol. A good protocol for reliable messages is WebSocket. To send a message on a WebSocket connection: let connection: NWConnection = … let message: Data = … let metadata = NWProtocolWebSocket.Metadata(opcode: .binary) let context = NWConnection.ContentContext(identifier: "send", metadata: [metadata]) connection.send(content: message, contentContext: context, completion: .contentProcessed({ error in // … check `error` … _ = error })) In WebSocket, the content identifier is ignored. Using an arbitrary fixed value, like the send in this example, is just fine. Multipeer Connectivity allows you to send a message to multiple peers in a single send call. In Network framework each send call targets a specific connection. To send a message to multiple peers, make a send call on the connection associated with each peer. If your app needs to transfer arbitrary amounts of data on a connection, it must implement flow control. See Start a stream, below. To receive messages on a WebSocket connection: func startWebSocketReceive(on connection: NWConnection) { connection.receiveMessage { message, _, _, error in if let error { … handle the error … return } if let message { … handle the incoming message … } startWebSocketReceive(on: connection) } } IMPORTANT WebSocket preserves message boundaries, which is one of the reasons why it’s ideal for your reliable messaging connections. If you use a streaming protocol, like TCP or QUIC streams, you must do your own framing. A good way to do that is with NWProtocolFramer. If you need the metadata associated with the message, get it from the context parameter: connection.receiveMessage { message, context, _, error in … if let message, let metadata = context?.protocolMetadata(definition: NWProtocolWebSocket.definition) as? NWProtocolWebSocket.Metadata { … handle the incoming message and its metadata … } … } Send and receive best effort messages In Multipeer Connectivity, a single session supports both reliable and best effort send modes. In Network framework, a connection is either reliable or best effort, depending on the underlying network protocol. The exact mechanism for sending a message depends on the underlying network protocol. A good protocol for best effort messages is UDP. To send a message on a UDP connection: let connection: NWConnection = … let message: Data = … connection.send(content: message, completion: .idempotent) IMPORTANT UDP datagrams have a theoretical maximum size of just under 64 KiB. However, sending a large datagram results in IP fragmentation, which is very inefficient. For this reason, Network framework prevents you from sending UDP datagrams that will be fragmented. To find the maximum supported datagram size for a connection, gets its maximumDatagramSize property. To receive messages on a UDP connection: func startUDPReceive(on connection: NWConnection) { connection.receiveMessage { message, _, _, error in if let error { … handle the error … return } if let message { … handle the incoming message … } startUDPReceive(on: connection) } } This is exactly the same code as you’d use for WebSocket. Start a stream In Multipeer Connectivity, you can ask the session to start a stream to a specific peer. There are two ways to achieve this in Network framework: If you’re using QUIC for your reliable connection, start a new QUIC stream over that connection. This is one place that QUIC shines. You can run an arbitrary number of QUIC connections over a single QUIC connection group, and QUIC manages flow control (see below) for each connection and for the group as a whole. If you’re using some other protocol for your reliable connection, like WebSocket, you must start a new connection. You might use TCP for this new connection, but it’s not unreasonable to use WebSocket or QUIC. If you need to open a new connection for your stream, you can manage that process over your reliable connection. Choose a protocol to match your send mode explains the general approach for this, although in that case it’s opening a parallel best effort UDP connection rather than a parallel stream connection. The main reason to start a new stream is that you want to send a lot of data to the remote peer. In that case you need to worry about flow control. Flow control applies to both the send and receive side. IMPORTANT Failing to implement flow control can result in unbounded memory growth in your app. This is particularly bad on iOS, where jetsam will terminate your app if it uses too much memory. On the send side, implement flow control by waiting for the connection to call your completion handler before generating and sending more data. For example, on a TCP connection or QUIC stream you might have code like this: func sendNextChunk(on connection: NWConnection) { let chunk: Data = … read next chunk from disk … connection.send(content: chunk, completion: .contentProcessed({ error in if let error { … handle error … return } sendNextChunk(on: connection) })) } This acts like an asynchronous loop. The first send call completes immediately because the connection just copies the data to its send buffer. In response, your app generates more data. This continues until the connection’s send buffer fills up, at which point it defers calling your completion handler. Eventually, the connection moves enough data across the network to free up space in its send buffer, and calls your completion handler. Your app generates another chunk of data For best performance, use a chunk size of at least 64 KiB. If you’re expecting to run on a fast device with a fast network, a chunk size of 1 MiB is reasonable. Receive-side flow control is a natural extension of the standard receive pattern. For example, on a TCP connection or QUIC stream you might have code like this: func receiveNextChunk(on connection: NWConnection) { let chunkSize = 64 * 1024 connection.receive(minimumIncompleteLength: chunkSize, maximumLength: chunkSize) { chunk, _, isComplete, error in if let chunk { … write chunk to disk … } if isComplete { … close the file … return } if let error { … handle the error … return } receiveNextChunk(on: connection) } } IMPORTANT The above is cast in terms of writing the chunk to disk. That’s important, because it prevents unbounded memory growth. If, for example, you accumulated the chunks into an in-memory buffer, that buffer could grow without bound, which risks jetsam terminating your app. The above assumes that you can read and write chunks of data synchronously and promptly, for example, reading and writing a file on a local disk. That’s not always the case. For example, you might be writing data to an accessory over a slow interface, like Bluetooth LE. In such cases you need to read and write each chunk asynchronously. This results in a structure where you read from an asynchronous input and write to an asynchronous output. For an example of how you might approach this, albeit in a very different context, see Handling Flow Copying. Send a resource In Multipeer Connectivity, you can ask the session to send a complete resource, identified by either a file or HTTP URL, to a specific peer. Network framework has no equivalent support for this, but you can implement it on top of a stream: To send, open a stream and then read chunks of data using URLSession and send them over that stream. To receive, open a stream and then receive chunks of data from that stream and write those chunks to disk. In this situation it’s critical to implement flow control, as described in the previous section. Final notes This section collects together some general hints and tips. Concurrency In Multipeer Connectivity, each MCSession has its own internal queue and calls delegate callbacks on that queue. In Network framework, you get to control the queue used by each object for its callbacks. A good pattern is to have a single serial queue for all networking, including your listener and all connections. In a simple app it’s reasonable to use the main queue for networking. If you do this, be careful not to do CPU intensive work in your networking callbacks. For example, if you receive a message that holds JPEG data, don’t decode that data on the main queue. Overriding protocol defaults Many network protocols, most notably TCP and QUIC, are intended to be deployed at vast scale across the wider Internet. For that reason they use default options that aren’t optimised for local networking. Consider changing these defaults in your app. TCP has the concept of a send timeout. If you send data on a TCP connection and TCP is unable to successfully transfer it to the remote peer within the send timeout, TCP will fail the connection. The default send timeout is infinite. TCP just keeps trying. To change this, set the connectionDropTime property. TCP has the concept of keepalives. If a connection is idle, TCP will send traffic on the connection for two reasons: If the connection is running through a NAT, the keepalives prevent the NAT mapping from timing out. If the remote peer is inaccessible, the keepalives fail, which in turn causes the connection to fail. This prevents idle but dead connections from lingering indefinitely. TCP keepalives default to disabled. To enable and configure them, set the enableKeepalive property. To configure their behaviour, set the keepaliveIdle, keepaliveCount, and keepaliveInterval properties. Symbol cross reference If you’re not sure where to start with a specific Multipeer Connectivity construct, find it in the tables below and follow the link to the relevant section. [Sorry for the poor formatting here. DevForums doesn’t support tables properly, so I’ve included the tables as preformatted text.] | For symbol | See | | ----------------------------------- | --------------------------- | | `MCAdvertiserAssistant` | *Discover peers* | | `MCAdvertiserAssistantDelegate` | *Discover peers* | | `MCBrowserViewController` | *Discover peers* | | `MCBrowserViewControllerDelegate` | *Discover peers* | | `MCNearbyServiceAdvertiser` | *Discover peers* | | `MCNearbyServiceAdvertiserDelegate` | *Discover peers* | | `MCNearbyServiceBrowser` | *Discover peers* | | `MCNearbyServiceBrowserDelegate` | *Discover peers* | | `MCPeerID` | *Create a peer identifier* | | `MCSession` | See below. | | `MCSessionDelegate` | See below. | Within MCSession: | For symbol | See | | --------------------------------------------------------- | ------------------------------------ | | `cancelConnectPeer(_:)` | *Manage a connection* | | `connectedPeers` | *Manage a listener* | | `connectPeer(_:withNearbyConnectionData:)` | *Manage a connection* | | `disconnect()` | *Manage a connection* | | `encryptionPreference` | *Plan for security* | | `myPeerID` | *Create a peer identifier* | | `nearbyConnectionData(forPeer:withCompletionHandler:)` | *Discover peers* | | `securityIdentity` | *Plan for security* | | `send(_:toPeers:with:)` | *Send and receive reliable messages* | | `sendResource(at:withName:toPeer:withCompletionHandler:)` | *Send a resource* | | `startStream(withName:toPeer:)` | *Start a stream* | Within MCSessionDelegate: | For symbol | See | | ---------------------------------------------------------------------- | ------------------------------------ | | `session(_:didFinishReceivingResourceWithName:fromPeer:at:withError:)` | *Send a resource* | | `session(_:didReceive:fromPeer:)` | *Send and receive reliable messages* | | `session(_:didReceive:withName:fromPeer:)` | *Start a stream* | | `session(_:didReceiveCertificate:fromPeer:certificateHandler:)` | *Plan for security* | | `session(_:didStartReceivingResourceWithName:fromPeer:with:)` | *Send a resource* | | `session(_:peer:didChange:)` | *Manage a connection* | Revision History 2025-04-11 Added some advice as to whether to use the peer identifier in your service name. Expanded the discussion of how to deduplicate connections in a star network architecture. 2025-03-20 Added a link to the DeviceDiscoveryUI framework to the Discovery UI section. Made other minor editorial changes. 2025-03-11 Expanded the Enable peer-to-peer Wi-Fi section to stress the importance of stopping network operations once you’re done with them. Added a link to that section from the list of Multipeer Connectivity drawbacks. 2025-03-07 First posted.

I just want Mac Catalyst app can look up the SSID of the currently connected WiFI. Xcode returns I can't use CoreWLan in Mac Catalyst, so I used NEHotspotNetwork, although I do not have convince whether Mac Catalyst allows it. The same code of destination works fine on iPhone, but not on Mac Catalyst and Mac(Designed for iPad). What is the proper way to get SSID of WiFI in Mac Catalyst? Is there another way to do this? The code I tried is below and I used CoreLocation API before call this function. func getWiFiSsid() { NEHotspotNetwork.fetchCurrent { network in if let network = network { print(network) } else { print("network is nil!") } } } Below is Entitlement file. Entitlements for app sandbox is removed when I run in Mac(Designed for iPad). <?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd"> <plist version="1.0"> <dict> <key>com.apple.developer.networking.HotspotConfiguration</key> <true/> <key>com.apple.developer.networking.networkextension</key> <array/> <key>com.apple.developer.networking.wifi-info</key> <true/> <key>com.apple.security.app-sandbox</key> <true/> <key>com.apple.security.network.client</key> <true/> <key>com.apple.security.network.server</key> <true/> <key>com.apple.security.personal-information.location</key> <true/> </dict> </plist> Below is Info.plist file. <?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd"> <plist version="1.0"> <dict> <key>CFBundleDevelopmentRegion</key> <string>$(DEVELOPMENT_LANGUAGE)</string> <key>CFBundleExecutable</key> <string>$(EXECUTABLE_NAME)</string> <key>CFBundleIdentifier</key> <string>$(PRODUCT_BUNDLE_IDENTIFIER)</string> <key>CFBundleInfoDictionaryVersion</key> <string>6.0</string> <key>CFBundleName</key> <string>$(PRODUCT_NAME)</string> <key>CFBundlePackageType</key> <string>APPL</string> <key>CFBundleShortVersionString</key> <string>1.0</string> <key>CFBundleVersion</key> <string>1</string> <key>LSRequiresIPhoneOS</key> <true/> <key>UILaunchStoryboardName</key> <string>LaunchScreen</string> <key>UIMainStoryboardFile</key> <string>Main</string> <key>UIRequiredDeviceCapabilities</key> <array> <string>armv7</string> </array> <key>UISupportedInterfaceOrientations</key> <array> <string>UIInterfaceOrientationPortrait</string> <string>UIInterfaceOrientationLandscapeLeft</string> <string>UIInterfaceOrientationLandscapeRight</string> </array> <key>UISupportedInterfaceOrientations~ipad</key> <array> <string>UIInterfaceOrientationPortrait</string> <string>UIInterfaceOrientationPortraitUpsideDown</string> <string>UIInterfaceOrientationLandscapeLeft</string> <string>UIInterfaceOrientationLandscapeRight</string> </array> <key>NSLocationUsageDescription</key> <string>Determine whether the ssid of current Wi-Fi connection</string> <key>NSLocationWhenInUseUsageDescription</key> <string>Determine whether the ssid of current Wi-Fi connection</string> </dict> </plist> The console log is below. NEHotspotNetwork nehelper sent invalid result code [1] for Wi-Fi information request

We have developed a DNS filter extension that works for most applications, but it does not receive all DNS queries. In particular, if we have our extension installed and enabled, we see Safari browsing cause local DNS servers to be used instead of going through our extension. What is the logic for how DNS servers vs. extensions are chosen to resolve DNS queries?

Is this technical solution reasonable about WKWebView on cross-domain issues ? Hi，all My project use WKWebView to load offline package, such as .html/.css/.js，and also request some resources from remote server to update pages. So there is a cross-domain problem with local file(file://xxx) and remote domain (https://xxx), is this following technical solution reasonable to fix this problem: 1. Create a custom URLSchemeHandler which conforms to WKURLSchemeHandler 2.Unify local file and remote domain request to https request 3. Hook WKWebView https request 4. Implement WKURLSchemeHandler delegate method (void)webView:(WKWebView *)webView startURLSchemeTask:(id)urlSchemeTask { NSURL *url = urlSchemeTask.request.URL; if ([url.pathExtension isEqualToString:@"html"]) { NSData *data = [[NSData alloc] initWithContentsOfFile:localFilePath]; NSMutableDictionary resHeader = [NSMutableDictionary new]; [resHeader setValue:@"" forKey:@"Access-Control-Allow-Origin"]; [resHeader setValue:@"charset=UTF-8" forKey:@"Content-Type"]; [resHeader setValue:@"text/html" forKey:@"Content-Type"]; NSHTTPURLResponse *response = [[NSHTTPURLResponse alloc] initWithURL:url statusCode:200 HTTPVersion:@"HTTP/1.1" headerFields:resHeader]; [urlSchemeTask didReceiveResponse:response]; [urlSchemeTask didReceiveData:data]; [urlSchemeTask didFinish]; } else { NSURLSession *defaultSession = [NSURLSession sharedSession]; NSURLSessionTask *dataTask = [defaultSession dataTaskWithRequest:urlSchemeTask.request completionHandler:^(NSData * _Nullable data, NSURLResponse * _Nullable response, NSError * _Nullable error) { [urlSchemeTask didReceiveResponse:response]; [urlSchemeTask didReceiveData:data]; [urlSchemeTask didFinish]; }]; [dataTask resume]; } } Is this technical solution reasonable? and is there any issues that I haven't considered? Sincerely, Looking forward to your reply

I would like to test running some Thread Networking code on my MacOS machine: import ThreadNetwork let client = THClient() let bIsPreferredAvailable = await client.isPreferredAvailable() but I get some errors when trying to create an instance of the THClient class: Client: -[THClient connectToXPCService]_block_invoke - CTCS XPC Client is interrupted. Client: -[THClient getConnectionEntitlementValidity]_block_invoke - clientProxyWithErrorHandler Error: Error Domain=NSCocoaErrorDomain Code=4097 "connection to service named com.apple.ThreadNetwork.xpc" UserInfo={NSDebugDescription=connection to service named com.apple.ThreadNetwork.xpc} Client: -[THClient init] - XPC Client Init Failed Invalidating XPC connection. Client: -[THClient getConnectionEntitlementValidity]_block_invoke - clientProxyWithErrorHandler Error: Error Domain=NSCocoaErrorDomain Code=4097 "connection to service named com.apple.ThreadNetwork.xpc" UserInfo={NSDebugDescription=connection to service named com.apple.ThreadNetwork.xpc} How can I get the code to run?

I have a TVML style app on the app store that no longer seems to work. I'm working on converting it to SwiftUI after seeing the WWDC video "Migrate your TVML app to SwiftUI". I've got most of the code working up until I'm trying to display video from a remote source (my website). It looks like the network connection is blocked, maybe. On a macOS app I see a App Sandbox capabilities that include Network access. I don't see that option for the tvOS app. Am I missing something or is it not needed, and I should look elsewhere? Thanks, David

hello I am testing the use of network extension. When we use dnsproxy to proxy DNS requests, we will send you a message that the udp pcbcount of your system continues to increase. For example for ((i=1; i<=99999; i++));do echo "Attempt $i:" dig google.com done when the dig command is used continuously, the dig command will show the following errors when pcbcount reaches a certain number. isc_socket_bind: address not available Can you help us determine what the problem might be? thank you

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" Don’t Try to Get the Device’s IP Address I regularly see questions like: How do I find the IP address of the device? How do I find the IP address of the Wi-Fi interface? How do I identify the Wi-Fi interface? I also see a lot of really bad answers to these questions. That’s understandable, because the questions themselves don’t make sense. Networking on Apple platforms is complicated and many of the things that are ‘obviously’ true are, in fact, not true at all. For example: There’s no single IP address that represents the device, or an interface. A device can have 0 or more interfaces, each of which can have 0 or more IP addresses, each of which can be IPv4 and IPv6. A device can have multiple interfaces of a given type. It’s common for iPhones to have multiple WWAN interfaces, for example. It’s not possible to give a simple answer to any of these questions, because the correct answer depends on the context. Why do you need this particular information? What are you planning to do with it? This post describes the scenarios I most commonly encounter, with my advice on how to handle each scenario. IMPORTANT BSD interface names, like en0, are not considered API. There’s no guarantee, for example, that an iPhone’s Wi-Fi interface is en0. If you write code that relies on a hard-coded interface name, it will fail in some situations. Service Discovery Some folks want to identify the Wi-Fi interface so that they can run a custom service discovery protocol over it. Before you do that, I strongly recommend that you look at Bonjour. This has a bunch of advantages: It’s an industry standard [1]. It’s going to be more efficient on the ‘wire’. You don’t have to implement it yourself, you can just call an API [2]. For information about the APIs available, see TN3151 Choosing the right networking API. If you must implement your own service discovery protocol, don’t think in terms of finding the Wi-Fi interface. Rather, write your code to work with all Wi-Fi interfaces, or perhaps even all Ethernet-like interfaces. That’s what Apple’s Bonjour implementation does, and it means that things will work in odd situations [3]. To find all Wi-Fi interfaces, get the interface list and filter it for ones with the Wi-Fi functional type. To find all broadcast-capable interfaces, get the interface list and filter it for interfaces with the IFF_BROADCAST flag set. If the service you’re trying to discover only supports IPv4, filter out any IPv6-only interfaces. For advice on how to do this, see Interface List and Network Interface Type in Network Interface APIs. When working with multiple interfaces, it’s generally a good idea to create a socket per interface and then bind that socket to the interface. That ensures that, when you send a packet, it’ll definitely go out the interface you expect. For more information on how to implement broadcasts correctly, see Broadcasts and Multicasts, Hints and Tips. [1] Bonjour is an Apple term for: RFC 3927 Dynamic Configuration of IPv4 Link-Local Addresses RFC 6762 Multicast DNS RFC 6763 DNS-Based Service Discovery [2] That’s true even on non-Apple platforms. It’s even true on most embedded platforms. If you’re talking to a Wi-Fi accessory, see Working with a Wi-Fi Accessory. [3] Even if the service you’re trying to discover can only be found on Wi-Fi, it’s possible for a user to have their iPhone on an Ethernet that’s bridged to a Wi-Fi. Why on earth would they do that? Well, security, of course. Some organisations forbid their staff from using Wi-Fi. Logging and Diagnostics Some folks want to log the IP address of the Wi-Fi interface, or the WWAN, or both for diagnostic purposes. This is quite feasible, with the only caveat being there may be multiple interfaces of each type. To find all interfaces of a particular type, get the interface list and filter it for interfaces with that functional type. See Interface List and Network Interface Type in Network Interface APIs. Interface for an Outgoing Connection There are situations where you need to get the interface used by a particular connection. A classic example of that is FTP. When you set up a transfer in FTP, you start with a control connection to the FTP server. You then open a listener and send its IP address and port to the FTP server over your control connection. What IP address should you use? There’s an easy answer here: Use the local IP address for the control connection. That’s the one that the server is most likely to be able to connect to. To get the local address of a connection: In Network framework, first get the currentPath property and then get its localEndpoint property. In BSD Sockets, use getsockname. See its man page for details. Now, this isn’t a particularly realistic example. Most folks don’t use FTP these days [1] but, even if they do, they use FTP passive mode, which avoids the need for this technique. However, this sort of thing still does come up in practice. I recently encountered two different variants of the same problem: One developer was implementing VoIP software and needed to pass the devices IP address to their VoIP stack. The best IP address to use was the local IP address of their control connection to the VoIP server. A different developer was upgrading the firmware of an accessory. They do this by starting a server within their app and sending a command to the accessory to download the firmware from that server. Again, the best IP address to use is the local address of the control connection. [1] See the discussion in TN3151 Choosing the right networking API. Listening for Connections If you’re listening for incoming network connections, you don’t need to bind to a specific address. Rather, listen on all local addresses. In Network framework, this is the default for NWListener. In BSD Sockets, set the address to INADDR_ANY (IPv4) or in6addr_any (IPv6). If you only want to listen on a specific interface, don’t try to bind to that interface’s IP address. If you do that, things will go wrong if the interface’s IP address changes. Rather, bind to the interface itself: In Network framework, set either the requiredInterfaceType property or the requiredInterface property on the NWParameters you use to create your NWListener. In BSD Sockets, set the IP_BOUND_IF (IPv4) or IPV6_BOUND_IF (IPv6) socket option. How do you work out what interface to use? The standard technique is to get the interface list and filter it for interfaces with the desired functional type. See Interface List and Network Interface Type in Network Interface APIs. Remember that their may be multiple interfaces of a given type. If you’re using BSD Sockets, where you can only bind to a single interface, you’ll need to create multiple listeners, one for each interface. Listener UI Some apps have an embedded network server and they want to populate a UI with information on how to connect to that server. This is a surprisingly tricky task to do correctly. For the details, see Showing Connection Information for a Local Server. Outgoing Connections In some situations you might want to force an outgoing connection to run over a specific interface. There are four common cases here: Set the local address of a connection [1]. Force a connection to run over a specific interface. Force a connection to run over a type of interface. Force a connection to run over an interface with specific characteristics. For example, you want to download some large resource without exhausting the user’s cellular data allowance. The last case should be the most common — see the Constraints section of Network Interface Techniques — but all four are useful in specific circumstances. The following sections explain how to tackle these tasks in the most common networking APIs. [1] This implicitly forces the connection to use the interface with that address. For an explanation as to why, see the discussion of scoped routing in Network Interface Techniques. Network Framework Network framework has good support for all of these cases. Set one or more of the following properties on the NWParameters object you use to create your NWConnection: requiredLocalEndpoint property requiredInterface property prohibitedInterfaces property requiredInterfaceType property prohibitedInterfaceTypes property prohibitConstrainedPaths property prohibitExpensivePaths property Foundation URL Loading System URLSession has fewer options than Network framework but they work in a similar way: Set one or more of the following properties on the URLSessionConfiguration object you use to create your session: allowsCellularAccess property allowsConstrainedNetworkAccess property allowsExpensiveNetworkAccess property Note While these session configuration properties are also available on URLRequest, it’s better to configure this on the session. There’s no option that forces a connection to run over a specific interface. In most cases you don’t need this — it’s better to use the allowsConstrainedNetworkAccess and allowsExpensiveNetworkAccess properties — but there are some situations where that’s necessary. For advice on this front, see Running an HTTP Request over WWAN. BSD Sockets BSD Sockets has very few options in this space. One thing that’s easy and obvious is setting the local address of a connection: Do that by passing the address to bind. Alternatively, to force a connection to run over a specific interface, set the IP_BOUND_IF (IPv4) or IPV6_BOUND_IF (IPv6) socket options. Revision History 2025-01-21 Added a link to Broadcasts and Multicasts, Hints and Tips. Made other minor editorial changes. 2023-07-18 First posted.

Based on threads from past years, it is mentioned that a NEFilterDataProvider supports IPPROTO_TCP, IPPROTO_UDP, IPPROTO_ICMP and IPPROTO_IGMP. [Q] What about IPPROTO_RAW? Is this something that would have been added recently?

I asked this question of AI and it said that yes it was possible, and gave some sample code override class func filterConfiguration() -> ILMessageFilterExtensionConfiguration { let config = ILMessageFilterExtensionConfiguration() // You can specify multiple network URLs config.networkURLs = [ URL(string: "https://api1.example.com/filter")!, URL(string: "https://api2.example.com/filter")! ] return config } And said the OS will try the first, and if there's no response within the first few seconds it'll move onto the second. However, there is no such class as ILMessageFilterExtensionConfiguration AFAICT, if there is then how to access/use it, if there isn't, then I wonder how the AI counjured it up? If multiple urls can be specified, then can the extension also specify a particular API to use and switch between them at some point? When does the OS call filterConfiguration()?

I'm using the NEHotspostConfigurationManager to join the WiFi network of a configured accessory. While this is all nice and dandy, I wonder why I'm still connected to said WiFi when I (force-)close the app. Wouldn't it be more useful to reconnect to the last network before?

I am developing an application that processes a video file stored on a server. I use URLSessionDataTask with a delegate handler to download the file. It is not necessary to download the entire file at once. Instead, I can load small chunks of the file as needed. This approach helps minimize memory consumption. I am trying to design a network layer that supports this behavior. Ideally, I would like to have an interface similar to: func readMoreData(length: Int) async throws -> Data Problems I Encountered: It seems that URLSessionDataTask does not allow controlling how many bytes will be downloaded. It always downloads the entire request. If I call suspend on URLSessionDataTask, the network activity does not stop, and the file keeps downloading. If I upgrade the dataTask to a StreamTask, the file still downloads, though reading bytes can be done through the StreamTask API. I would prefer behavior similar to AsyncHTTPClient (a Swift Server library) or Network Framework. These frameworks allow controlling the number of bytes downloaded at a time. Unfortunately, they do not fit the specific requirements of my project. Am I correct in understanding that controlling the download process is not possible with URLSessionDataTask? As a possible solution, I am considering using HTTP Range Requests, though this would increase the number of additional server requests, which I would like to avoid.