General: Forums subtopic: App & System Services > Networking TN3151 Choosing the right networking API Networking Overview document — Despite the fact that this is in the archive, this is still really useful. TLS for App Developers forums post Choosing a Network Debugging Tool documentation WWDC 2019 Session 712 Advances in Networking, Part 1 — This explains the concept of constrained networking, which is Apple’s preferred solution to questions like How do I check whether I’m on Wi-Fi? TN3135 Low-level networking on watchOS TN3179 Understanding local network privacy Adapt to changing network conditions tech talk Understanding Also-Ran Connections forums post Extra-ordinary Networking forums post Foundation networking: Forums tags: Foundation, CFNetwork URL Loading System documentation — NSURLSession, or URLSession in Swift, is the recommended API for HTTP[S] on Apple platforms. Moving to Fewer, Larger Transfers forums post Testing Background Session Code forums post Network framework: Forums tag: Network Network framework documentation — Network framework is the recommended API for TCP, UDP, and QUIC on Apple platforms. Building a custom peer-to-peer protocol sample code (aka TicTacToe) Implementing netcat with Network Framework sample code (aka nwcat) Configuring a Wi-Fi accessory to join a network sample code Moving from Multipeer Connectivity to Network Framework forums post NWEndpoint History and Advice forums post Network Extension (including Wi-Fi on iOS): See Network Extension Resources Wi-Fi Fundamentals TN3111 iOS Wi-Fi API overview Wi-Fi Aware framework documentation Wi-Fi on macOS: Forums tag: Core WLAN Core WLAN framework documentation Wi-Fi Fundamentals Secure networking: Forums tags: Security Apple Platform Security support document Preventing Insecure Network Connections documentation — This is all about App Transport Security (ATS). WWDC 2017 Session 701 Your Apps and Evolving Network Security Standards [1] — This is generally interesting, but the section starting at 17:40 is, AFAIK, the best information from Apple about how certificate revocation works on modern systems. Available trusted root certificates for Apple operating systems support article Requirements for trusted certificates in iOS 13 and macOS 10.15 support article About upcoming limits on trusted certificates support article Apple’s Certificate Transparency policy support article What’s new for enterprise in iOS 18 support article — This discusses new key usage requirements. Technote 2232 HTTPS Server Trust Evaluation Technote 2326 Creating Certificates for TLS Testing QA1948 HTTPS and Test Servers Miscellaneous: More network-related forums tags: 5G, QUIC, Bonjour On FTP forums post Using the Multicast Networking Additional Capability forums post Investigating Network Latency Problems forums post WirelessInsights framework documentation iOS Network Signal Strength forums post Share and Enjoy — Quinn “The Eskimo!” @ Developer Technical Support @ Apple let myEmail = "eskimo" + "1" + "@" + "apple.com" [1] This video is no longer available from Apple, but the URL should help you locate other sources of this info.

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" On Host Names I commonly see questions like How do I get the device’s host name? This question doesn’t make sense without more context. Apple systems have a variety of things that you might consider to be the host name: The user-assigned device name — This is a user-visible value, for example, Guy Smiley. People set this in Settings > General > About > Name. The local host name — This is a DNS name used by Bonjour, for example, guy-smiley.local. By default this is algorithmically derived from the user-assigned device name. On macOS, people can override this in Settings > General > Sharing > Local hostname. The reverse DNS name associated with the various IP addresses assigned to the device’s various network interfaces That last one is pretty much useless. You can’t get a single host name because there isn’t a single IP address. For more on that, see Don’t Try to Get the Device’s IP Address. The other two have well-defined answers, although those answers vary by platform. I’ll talk more about that below. Before getting to that, however, let’s look at the big picture. Big Picture The use cases for the user-assigned device name are pretty clear. I rarely see folks confused about that. Another use case for this stuff is that you’ve started a server and you want to tell the user how to connect to it. I discuss this in detail in Showing Connection Information in an iOS Server. However, most folks who run into problems like this do so because they’re suffering from one of the following misconceptions: The device has a DNS name. Its DNS name is unique. Its DNS name doesn’t change. Its DNS name is in some way useful for networking. Some of these may be true in some specific circumstances, but none of them are true in all circumstances. These issues are not unique to Apple platforms — if you look at the Posix spec for gethostname, it says nothing about DNS! — but folks tend to notice these problems more on Apple platforms because Apple devices are often deployed to highly dynamic network environments. So, before you start using the APIs discussed in this post, think carefully about your assumptions. And if you actually do want to work with DNS, there are two cases to consider: If you’re looking for the local host name, use the APIs discussed above. In other cases, it’s likely that the APIs in this post will not be helpful and you’d be better off focusing on DNS APIs [1]. [1] The API I recommend for this is DNS-SD. See the DNS section in TN3151 Choosing the right networking API. macOS To get the user-assigned device name, call the SCDynamicStoreCopyComputerName(_:_:) function. For example: let userAssignedDeviceName = SCDynamicStoreCopyComputerName(nil, nil) as String? To get the local host name, call the SCDynamicStoreCopyLocalHostName(_:) function. For example: let localHostName = SCDynamicStoreCopyLocalHostName(nil) as String? IMPORTANT This returns just the name label. To form a local host name, append .local.. Both routines return an optional result; code defensively! If you’re displaying these values to the user, use the System Configuration framework dynamic store notification mechanism to keep your UI up to date. iOS and Friends On iOS, iPadOS, tvOS, and visionOS, get the user-assigned device name from the name property on UIDevice. IMPORTANT Access to this is now restricted. For more on that, see the documentation for the com.apple.developer.device-information.user-assigned-device-name entitlement. There is no direct mechanism to get the local host name. Other APIs There are a wide variety of other APIs that purport to return the host name. These include: gethostname The name property on NSHost [1] The hostName property on NSProcessInfo (ProcessInfo in Swift) These are problematic for a number of reasons: They have a complex implementation that makes it hard to predict what value you’ll get back. They might end up trying to infer the host name from the network environment. The existing behaviour is hard to change due to compatibility concerns. Some of them are marked as to-be-deprecated. IMPORTANT The second issue is particularly problematic, because it involves synchronous DNS requests [2]. That’s slow in general. Worse yet, if the network environment is restricted in some way, these calls can be very slow, taking about 30 seconds to time out. Given these problems, it’s generally best to avoid calling these routines at all. [1] It also has a names property, which is a little closer to reality but still not particularly useful. [2] Actually, that’s not true for gethostname. Rather, that call just returns whatever was last set by sethostname. This is always fast. The System Configuration framework infrastructure calls sethostname to update the host name as the system state changes.

Starting in iOS 26, two notable changes have been made to CallKit, LiveCommunicationKit, and the PushToTalk framework: As a diagnostic aid, we're introducing new dialogs to warn apps of voip push related issue, for example when they fail to report a call or when when voip push delivery stops. The specific details of that behavior are still being determined and are likely to change over time, however, the critical point here is that these alerts are only intended to help developers debug and improve their app. Because of that, they're specifically tied to development and TestFlight signed builds, so the alert dialogs will not appear for customers running app store builds. The existing termination/crashes will still occur, but the new warning alerts will not appear. As PushToTalk developers have previously been warned, the last unrestricted PushKit entitlement ("com.apple.developer.pushkit.unrestricted-voip.ptt") has been disabled in the iOS 26 SDK. ALL apps that link against the iOS 26 SDK which receive a voip push through PushKit and which fail to report a call to CallKit will be now be terminated by the system, as the API contract has long specified. __ Kevin Elliott DTS Engineer, CoreOS/Hardware

ios構成プロファイルの制限のallowCloudPrivateRelayのプライベートリレーの制御とRelayペイロードの機能は関係がありますか？ それとも別々の機能でしょうか？ ↓ s there a relationship between the private relay control in the iOS configuration profile restriction allowCloudPrivateRelay and the functionality of the Relay payload? Or are they separate features?

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" Broadcasts and Multicasts, Hints and Tips I regularly see folks struggle with broadcasts and multicasts on Apple platforms. This post is my attempt to clear up some of the confusion. This post covers both IPv4 and IPv6. There is, however, a key difference. In IPv4, broadcasts and multicasts are distinct concepts. In contrast, IPv6 doesn’t support broadcast as such; rather, it treats broadcasts as a special case of multicasts. IPv6 does have an all nodes multicast address, but it’s rarely used. Before reading this post, I suggest you familiarise yourself with IP addresses in general. A good place to start is The Fount of All Knowledge™. Service Discovery A lot of broadcast and multicast questions come from folks implementing their own service discovery protocol. I generally recommend against doing that, for the reasons outlined in the Service Discovery section of Don’t Try to Get the Device’s IP Address. There are, however, some good reasons to implement a custom service discovery protocol. For example, you might be working with an accessory that only supports this custom protocol [1]. If you must implement your own service discovery protocol, read this post and also read the advice in Don’t Try to Get the Device’s IP Address. IMPORTANT Sometimes I see folks implementing their own version of mDNS. This is almost always a mistake: If you’re using third-party tooling that includes its own mDNS implementation, it’s likely that this tooling allows you to disable that implementation and instead rely on the Bonjour support that’s built-in to all Apple platforms. If you’re doing some weird low-level thing with mDNS or DNS-SD, it’s likely that you can do that with the low-level DNS-SD API. [1] And whose firmware you can’t change! I talk more about this in Working with a Wi-Fi Accessory. API Choice Broadcasts and multicasts typically use UDP [1]. TN3151 Choosing the right networking API describes two recommended UDP APIs: Network framework BSD Sockets Our general advice is to prefer Network framework over BSD Sockets, but UDP broadcasts and multicasts are an exception to that rule. Network framework has very limited UDP broadcast support. And while it’s support for UDP multicasts is less limited, it’s still not sufficient for all UDP applications. In cases where Network framework is not sufficient, BSD Sockets is your only option. [1] It is possible to broadcast and multicast at the Ethernet level, but I almost never see questions about that. UDP Broadcasts in Network Framework Historically I’ve claimed that Network framework was useful for UDP broadcasts is very limited circumstances (for example, in the footnote on this post). I’ve since learnt that this isn’t the case. Or, more accurately, this support is so limited (r. 122924701) as to be useless in practice. For the moment, if you want to work with UDP broadcasts, your only option is BSD Sockets. UDP Multicasts in Network Framework Network framework supports UDP multicast using the NWConnectionGroup class with the NWMulticastGroup group descriptor. This support has limits. The most significant limit is that it doesn’t support broadcasts; it’s for multicasts only. Note This only relevant to IPv4. Remember that IPv6 doesn’t support broadcasts as a separate concept. There are other limitations, but I don’t have a good feel for them. I’ll update this post as I encounter issues. Local Network Privacy Some Apple platforms support local network privacy. This impacts broadcasts and multicasts in two ways: Broadcasts and multicasts require local network access, something that’s typically granted by the user. Broadcasts and multicasts are limited by a managed entitlement (except on macOS). TN3179 Understanding local network privacy has lots of additional info on this topic, including the list of platforms to which it applies. Send, Receive, and Interfaces When you broadcast or multicast, there’s a fundamental asymmetry between send and receive: You can reasonable receive datagrams on all broadcast-capable interfaces. But when you send a datagram, it has to target a specific interface. The sending behaviour is the source of many weird problems. Consider the IPv4 case. If you send a directed broadcast, you can reasonably assume it’ll be routed to the correct interface based on the network prefix. But folks commonly send an all-hosts broadcast (255.255.255.255), and it’s not obvious what happens in that case. Note If you’re unfamiliar with the terms directed broadcast and all-hosts broadcast, see IP address. The exact rules for this are complex, vary by platform, and can change over time. For that reason, it’s best to write your broadcast code to be interface specific. That is: Identify the interfaces on which you want to work. Create a socket per interface. Bind that socket to that interface. Note Use the IP_BOUND_IF (IPv4) or IPV6_BOUND_IF (IPv6) socket options rather than binding to the interface address, because the interface address can change over time. Extra-ordinary Networking has links to other posts which discuss these concepts and the specific APIs in more detail. Miscellaneous Gotchas A common cause of mysterious broadcast and multicast problems is folks who hard code BSD interface names, like en0. Doing that might work for the vast majority of users but then fail in some obscure scenarios. BSD interface names are not considered API and you must not hard code them. Extra-ordinary Networking has links to posts that describe how to enumerate the interface list and identify interfaces of a specific type. Don’t assume that there’ll be only one interface of a given type. This might seem obviously true, but it’s not. For example, our platforms support peer-to-peer Wi-Fi, so each device has multiple Wi-Fi interfaces. When sending a broadcast, don’t forget to enable the SO_BROADCAST socket option. If you’re building a sandboxed app on the Mac, working with UDP requires both the com.apple.security.network.client and com.apple.security.network.server entitlements. Some folks reach for broadcasts or multicasts because they’re sending the same content to multiple devices and they believe that it’ll be faster than unicasts. That’s not true in many cases, especially on Wi-Fi. For more on this, see the Broadcasts section of Wi-Fi Fundamentals. Snippets To send a UDP broadcast: func broadcast(message: Data, to interfaceName: String) throws { let fd = try FileDescriptor.socket(AF_INET, SOCK_DGRAM, 0) defer { try! fd.close() } try fd.setSocketOption(SOL_SOCKET, SO_BROADCAST, 1 as CInt) let interfaceIndex = if_nametoindex(interfaceName) guard interfaceIndex > 0 else { throw … } try fd.setSocketOption(IPPROTO_IP, IP_BOUND_IF, interfaceIndex) try fd.send(data: message, to: ("255.255.255.255", 2222)) } Note These snippet uses the helpers from Calling BSD Sockets from Swift. To receive UDP broadcasts: func receiveBroadcasts(from interfaceName: String) throws { let fd = try FileDescriptor.socket(AF_INET, SOCK_DGRAM, 0) defer { try! fd.close() } let interfaceIndex = if_nametoindex(interfaceName) guard interfaceIndex > 0 else { fatalError() } try fd.setSocketOption(IPPROTO_IP, IP_BOUND_IF, interfaceIndex) try fd.setSocketOption(SOL_SOCKET, SO_REUSEADDR, 1 as CInt) try fd.setSocketOption(SOL_SOCKET, SO_REUSEPORT, 1 as CInt) try fd.bind("0.0.0.0", 2222) while true { let (data, (sender, port)) = try fd.receiveFrom() … } } IMPORTANT This code runs synchronously, which is less than ideal. In a real app you’d run the receive asynchronously, for example, using a Dispatch read source. For an example of how to do that, see this post. If you need similar snippets for multicast, lemme know. I’ve got them lurking on my hard disk somewhere (-: Other Resources Apple’s official documentation for BSD Sockets is in the man pages. See Reading UNIX Manual Pages. Of particular interest are: setsockopt man page ip man page ip6 man page If you’re not familiar with BSD Sockets, I strongly recommend that you consult third-party documentation for it. BSD Sockets is one of those APIs that looks simple but, in reality, is ridiculously complicated. That’s especially true if you’re trying to write code that works on BSD-based platforms, like all of Apple’s platforms, and non-BSD-based platforms, like Linux. I specifically recommend UNIX Network Programming, by Stevens et al, but there are lots of good alternatives. https://unpbook.com Revision History 2025-09-01 Fixed a broken link. 2025-01-16 First posted.

Hi, We're receiving data via centralManager.centralManager.scanForPeripherals, with no options or filtering (for now), and in the func centralManager(_ central: CBCentralManager, didDiscover peripheral: CBPeripheral, advertisementData: [String : Any], rssi RSSI: NSNumber) callback, we get advertisementData for each bluetooth device found. But, I know one of my BLE devices is sending an Eddystone TLM payload, which generally is received into the kCBAdvDataServiceData part of the advertisementData dictionary, but, it doesn't show up. What is happening however (when comparing to other devices that do show that payload), is I've noticed the "isConnectable" part is false, and others have it true. Technically we're not "connecting" as such as we're simply reading passive advertisement data, but does that have any bearing on how CoreBluetooth decides to build up it's AdvertisementData response? Example (with serviceData; and I know this has Eddystone TLM) ["kCBAdvDataLocalName": FSC-BP105N, "kCBAdvDataRxPrimaryPHY": 1, "kCBAdvDataServiceUUIDs": <__NSArrayM 0x300b71f80>( FEAA, FEF5 ) , "kCBAdvDataTimestamp": 773270526.26279, "kCBAdvDataServiceData": { FFF0 = {length = 11, bytes = 0x36021892dc0d3015aeb164}; FEAA = {length = 14, bytes = 0x20000be680000339ffa229bbce8a}; }, "kCBAdvDataRxSecondaryPHY": 0, "kCBAdvDataIsConnectable": 1] Vs This also has Eddystone TLM configured ["kCBAdvDataLocalName": 100FA9FD-7000-1000, "kCBAdvDataIsConnectable": 0, "kCBAdvDataRxPrimaryPHY": 1, "kCBAdvDataRxSecondaryPHY": 0, "kCBAdvDataTimestamp": 773270918.97273] Any insight would be great to understand if the presence of other flags drive the exposure of ServiceData or not...

This is a topic that’s come up a few times on the forums, so I thought I’d write up a summary of the issues I’m aware of. If you have questions or comments, start a new thread in the App & System Services > Networking subtopic and tag it with Network Extension. That way I’ll be sure to see it go by. Share and Enjoy — Quinn “The Eskimo!” @ Developer Technical Support @ Apple let myEmail = "eskimo" + "1" + "@" + "apple.com" Network Extension Provider Packaging There are two ways to package a network extension provider: App extension ( appex ) System extension ( sysex ) Different provider types support different packaging on different platforms. See TN3134 Network Extension provider deployment for the details. Some providers, most notably packet tunnel providers on macOS, support both appex and sysex packaging. Sysex packaging has a number of advantages: It supports direct distribution, using Developer ID signing. It better matches the networking stack on macOS. An appex is tied to the logged in user, whereas a sysex, and the networking stack itself, is global to the system as a whole. Given that, it generally makes sense to package your Network Extension (NE) provider as a sysex on macOS. If you’re creating a new product that’s fine, but if you have an existing iOS product that you want to bring to macOS, you have to account for the differences brought on by the move to sysex packaging. Similarly, if you have an existing sysex product on macOS that you want to bring to iOS, you have to account for the appex packaging. This post summarises those changes. Keep the following in mind while reading this post: The information here applies to all NE providers that can be packaged as either an appex or a sysex. When this post uses a specific provider type in an example, it’s just an example. Unless otherwise noted, any information about iOS also applies to iPadOS, tvOS, and visionOS. Process Lifecycle With appex packaging, the system typically starts a new process for each instance of your NE provider. For example, with a packet tunnel provider: When the users starts the VPN, the system creates a process and then instantiates and starts the NE provider in that process. When the user stops the VPN, the system stops the NE provider and then terminates the process running it. If the user starts the VPN again, the system creates an entirely new process and instantiates and starts the NE provider in that. In contrast, with sysex packaging there’s typically a single process that runs all off the sysex’s NE providers. Returning to the packet tunnel provider example: When the users starts the VPN, the system instantiates and starts the NE provider in the sysex process. When the user stops the VPN, the system stops and deallocates the NE provider instances, but leaves the sysex process running. If the user starts the VPN again, the system instantiates and starts a new instances of the NE provider in the sysex process. This lifecycle reflects how the system runs the NE provider, which in turn has important consequences on what the NE provider can do: An appex acts like a launchd agent [1], in that it runs in a user context and has access to that user’s state. A sysex is effectively a launchd daemon. It runs in a context that’s global to the system as a whole. It does not have access to any single user’s state. Indeed, there might be no user logged in, or multiple users logged in. The following sections explore some consequences of the NE provider lifecycle. [1] It’s not actually run as a launchd agent. Rather, there’s a system launchd agent that acts as the host for the app extension. App Groups With an app extension, the app extension and its container app run as the same user. Thus it’s trivial to share state between them using an app group container. Note When talking about extensions on Apple platforms, the container app is the app in which the extension is embedded and the host app is the app using the extension. For network extensions the host app is the system itself. That’s not the case with a system extension. The system extension runs as root whereas the container app runs an the user who launched it. While both programs can claim access to the same app group, the app group container location they receive will be different. For the system extension that location will be inside the home directory for the root user. For the container app the location will be inside the home directory of the user who launched it. This does not mean that app groups are useless in a Network Extension app. App groups are also a factor in communicating between the container app and its extensions, the subject of the next section. IMPORTANT App groups have a long and complex history on macOS. For the full story, see App Groups: macOS vs iOS: Working Towards Harmony. Communicating with Extensions With an app extension there are two communication options: App-provider messages App groups App-provider messages are supported by NE directly. In the container app, send a message to the provider by calling sendProviderMessage(_:responseHandler:) method. In the appex, receive that message by overriding the handleAppMessage(_:completionHandler:) method. An appex can also implement inter-process communication (IPC) using various system IPC primitives. Both the container app and the appex claim access to the app group via the com.apple.security.application-groups entitlement. They can then set up IPC using various APIs, as explain in the documentation for that entitlement. With a system extension the story is very different. App-provider messages are supported, but they are rarely used. Rather, most products use XPC for their communication. In the sysex, publish a named XPC endpoint by setting the NEMachServiceName property in its Info.plist. Listen for XPC connections on that endpoint using the XPC API of your choice. Note For more information about the available XPC APIs, see XPC Resources. In the container app, connect to that named XPC endpoint using the XPC Mach service name API. For example, with NSXPCConnection, initialise the connection with init(machServiceName:options:), passing in the string from NEMachServiceName. To maximise security, set the .privileged flag. Note XPC Resources has a link to a post that explains why this flag is important. If the container app is sandboxed — necessary if you ship on the Mac App Store — then the endpoint name must be prefixed by an app group ID that’s accessible to that app, lest the App Sandbox deny the connection. See the app groups documentation for the specifics. When implementing an XPC listener in your sysex, keep in mind that: Your sysex’s named XPC endpoint is registered in the global namespace. Any process on the system can open a connection to it [1]. Your XPC listener must be prepared for this. If you want to restrict connections to just your container app, see XPC Resources for a link to a post that explains how to do that. Even if you restrict access in that way, it’s still possible for multiple instances of your container app to be running simultaneously, each with its own connection to your sysex. This happens, for example, if there are multiple GUI users logged in and different users run your container app. Design your XPC protocol with this in mind. Your sysex only gets one named XPC endpoint, and thus one XPC listener. If your sysex includes multiple NE providers, take that into account when you design your XPC protocol. [1] Assuming that connection isn’t blocked by some other mechanism, like the App Sandbox. Inter-provider Communication A sysex can include multiple types of NE providers. For example, a single sysex might include a content filter and a DNS proxy provider. In that case the system instantiates all of the NE providers in the same sysex process. These instances can communicate without using IPC, for example, by storing shared state in global variables (with suitable locking, of course). It’s also possible for a single container app to contain multiple sysexen, each including a single NE provider. In that case the system instantiates the NE providers in separate processes, one for each sysex. If these providers need to communicate, they have to use IPC. In the appex case, the system instantiates each provider in its own process. If two providers need to communicate, they have to use IPC. Managing Secrets An appex runs in a user context and thus can store secrets, like VPN credentials, in the keychain. On macOS this includes both the data protection keychain and the file-based keychain. It can also use a keychain access group to share secrets with its container app. See Sharing access to keychain items among a collection of apps. Note If you’re not familiar with the different types of keychain available on macOS, see TN3137 On Mac keychain APIs and implementations. A sysex runs in the global context and thus doesn’t have access to user state. It also doesn’t have access to the data protection keychain. It must use the file-based keychain, and specifically the System keychain. That means there’s no good way to share secrets with the container app. Instead, do all your keychain operations in the sysex. If the container app needs to work with a secret, have it pass that request to the sysex via IPC. For example, if the user wants to use a digital identity as a VPN credential, have the container app get the PKCS#12 data and password and then pass that to the sysex so that it can import the digital identity into the keychain. Memory Limits iOS imposes strict memory limits an NE provider appexen [1]. macOS imposes no memory limits on NE provider appexen or sysexen. [1] While these limits are not documented officially, you can get a rough handle on the current limits by reading the posts in this thread. Frameworks If you want to share code between a Mac app and its embedded appex, use a structure like this: MyApp.app/ Contents/ MacOS/ MyApp PlugIns/ MyExtension.appex/ Contents/ MacOS/ MyExtension … Frameworks/ MyFramework.framework/ … There’s one copy of the framework, in the app’s Frameworks directory, and both the app and the appex reference it. This approach works for an appex because the system always loads the appex from your app’s bundle. It does not work for a sysex. When you activate a sysex, the system copies it to a protected location. If that sysex references a framework in its container app, it will fail to start because that framework isn’t copied along with the sysex. The solution is to structure your app like this: MyApp.app/ Contents/ MacOS/ MyApp Library/ SystemExtensions/ MyExtension.systemextension/ Contents/ MacOS/ MyExtension Frameworks/ MyFramework.framework/ … … That is, have both the app and the sysex load the framework from the sysex’s Frameworks directory. When the system copies the sysex to its protected location, it’ll also copy the framework, allowing the sysex to load it. To make this work you have to change the default rpath configuration set up by Xcode. Read Dynamic Library Standard Setup for Apps to learn how that works and then tweak things so that: The framework is embedded in the sysex, not the container app. The container app has an additional LC_RPATH load command for the sysex’s Frameworks directory (@executable_path/../Library/SystemExtensions/MyExtension.systemextension/Contents/Frameworks). The sysex’s LC_RPATH load command doesn’t reference the container app’s Frameworks directory (@executable_path/../../../../Frameworks) but instead points to the sysex’s Framweorks directory (@executable_path/../Frameworks). Entitlements When you build an app with an embedded NE extension, both the app and the extension must be signed with the com.apple.developer.networking.networkextension entitlement. This is a restricted entitlement, that is, it must be authorised by a provisioning profile. The value of this entitlement is an array, and the values in that array differ depend on your distribution channel: If you distribute your app directly with Developer ID signing, use the values with the -systemextension suffix. Otherwise — including when you distribute the app on the App Store and when signing for development — use the values without that suffix. Make sure you authorise these values with your provisioning profile. If, for example, you use an App Store distribution profile with a Developer ID signed app, things won’t work because the profile doesn’t authorise the right values. In general, the easiest option is to use Xcode’s automatic code signing. However, watch out for the pitfall described in Exporting a Developer ID Network Extension. Revision History 2025-11-06 Added the Entitlements section. Explained that, with sysex packaging, multiple instances of your container app might connect simultaneously with your sysex. 2025-09-17 First posted.

Every now and again folks notice that Network framework seems to create an unexpected number of connections on the wire. This post explains why that happens and what you should do about it. If you have questions or comments, put them in a new thread here on the forums. Use the App & System Services > Networking topic area and the Network tag. Share and Enjoy — Quinn “The Eskimo!” @ Developer Technical Support @ Apple let myEmail = "eskimo" + "1" + "@" + "apple.com" Understanding Also-Ran Connections Network framework implements the Happy Eyeballs algorithm. That might create more on-the-wire connections than you expect. There are two common places where folks notice this: When looking at a packet trace When implementing a listener Imagine that you’ve implemented a TCP server using NWListener and you connect to it from a client using NWConnection. In many situations there are multiple network paths between the client and the server. For example, on a local network there’s always at least two paths: the link-local IPv6 path and either an infrastructure IPv4 path or the link-local IPv4 path. When you start your NWConnection, Network framework’s Happy Eyeballs algorithm might [1] start a TCP connection for each of these paths. It then races those connections. The one that connects first is the ‘winner’, and Network framework uses that connection for your traffic. Once it has a winner, the other connections, the also-ran connections, are redundant, and Network framework just closes them. You can observe this behaviour on the client side by looking in the system log. Many Network framework log entries (subsystem com.apple.network) contain a connection identifier. For example C8 is the eighth connection started by this process. Each connection may have child connections (C8.1, C8.2, …) and grandchild connections (C8.1.1, C8.1.2, …), and so on. You’ll see state transitions for these child connections occurring in parallel. For example, the following log entries show that C8 is racing the connection of two grandchild connections, C8.1.1 and C8.1.2: type: debug time: 12:22:26.825331+0100 process: TestAlsoRanConnections subsystem: com.apple.network category: connection message: nw_socket_connect [C8.1.1:1] Calling connectx(…) type: debug time: 12:22:26.964150+0100 process: TestAlsoRanConnections subsystem: com.apple.network category: connection message: nw_socket_connect [C8.1.2:1] Calling connectx(…) Note For more information about accessing the system log, see Your Friend the System Log. You also see this on the server side, but in this case each connection is visible to your code. When you connect from the client, Network framework calls your listener’s new connection handler with multiple connections. One of those is the winning connection and you’ll receive traffic on it. The others are the also-ran connections, and they close promptly. IMPORTANT Depending on network conditions there may be no also-ran connections. Or there may be lots of them. If you want to test the also-ran connection case, use Network Link Conditioner to add a bunch of delay to your packets. You don’t need to write special code to handle also-ran connections. From the perspective of your listener, these are simply connections that open and then immediately close. There’s no difference between an also-ran connection and, say, a connection from a client that immediately crashes. Or a connection generated by someone doing a port scan. Your server must be resilient to such things. However, the presence of these also-ran connections can be confusing, especially if you’re just getting started with Network framework, and hence this post. [1] This is “might” because the exact behaviour depends on network conditions. More on that below.

Most apps perform ordinary network operations, like fetching an HTTP resource with URLSession and opening a TCP connection to a mail server with Network framework. These operations are not without their challenges, but they’re the well-trodden path. If your app performs ordinary networking, see TN3151 Choosing the right networking API for recommendations as to where to start. Some apps have extra-ordinary networking requirements. For example, apps that: Help the user configure a Wi-Fi accessory Require a connection to run over a specific interface Listen for incoming connections Building such an app is tricky because: Networking is hard in general. Apple devices support very dynamic networking, and your app has to work well in whatever environment it’s running in. Documentation for the APIs you need is tucked away in man pages and doc comments. In many cases you have to assemble these APIs in creative ways. If you’re developing an app with extra-ordinary networking requirements, this post is for you. Note If you have questions or comments about any of the topics discussed here, put them in a new thread here on DevForums. Make sure I see it by putting it in the App & System Services > Networking area. And feel free to add tags appropriate to the specific technology you’re using, like Foundation, CFNetwork, Network, or Network Extension. Links, Links, and More Links Each topic is covered in a separate post: The iOS Wi-Fi Lifecycle describes how iOS joins and leaves Wi-Fi networks. Understanding this is especially important if you’re building an app that works with a Wi-Fi accessory. Network Interface Concepts explains how Apple platforms manage network interfaces. If you’ve got this far, you definitely want to read this. Network Interface Techniques offers a high-level overview of some of the more common techniques you need when working with network interfaces. Network Interface APIs describes APIs and core techniques for working with network interfaces. It’s referenced by many other posts. Running an HTTP Request over WWAN explains why most apps should not force an HTTP request to run over WWAN, what they should do instead, and what to do if you really need that behaviour. If you’re building an iOS app with an embedded network server, see Showing Connection Information in an iOS Server for details on how to get the information to show to your user so they can connect to your server. Many folks run into trouble when they try to find the device’s IP address, or other seemingly simple things, like the name of the Wi-Fi interface. Don’t Try to Get the Device’s IP Address explains why these problems are hard, and offers alternative approaches that function correctly in all network environments. Similarly, folks also run into trouble when trying to get the host name. On Host Names explains why that’s more complex than you might think. If you’re working with broadcasts or multicasts, see Broadcasts and Multicasts, Hints and Tips. If you’re building an app that works with a Wi-Fi accessory, see Working with a Wi-Fi Accessory. If you’re trying to gather network interface statistics, see Network Interface Statistics. There are also some posts that are not part of this series but likely to be of interest if you’re working in this space: TN3179 Understanding local network privacy discusses the local network privacy feature. Calling BSD Sockets from Swift does what it says on the tin, that is, explains how to call BSD Sockets from Swift. When doing weird things with the network, you often find yourself having to use BSD Sockets, and that API is not easy to call from Swift. The code therein is primarily for the benefit of test projects, oh, and DevForums posts like these. TN3111 iOS Wi-Fi API overview is a critical resource if you’re doing Wi-Fi specific stuff on iOS. TLS For Accessory Developers tackles the tricky topic of how to communicate securely with a network-based accessory. A Peek Behind the NECP Curtain discusses NECP, a subsystem that control which programs have access to which network interfaces. Networking Resources has links to many other useful resources. Share and Enjoy — Quinn “The Eskimo!” @ Developer Technical Support @ Apple let myEmail = "eskimo" + "1" + "@" + "apple.com" Revision History 2025-07-31 Added a link to A Peek Behind the NECP Curtain. 2025-03-28 Added a link to On Host Names. 2025-01-16 Added a link to Broadcasts and Multicasts, Hints and Tips. Updated the local network privacy link to point to TN3179. Made other minor editorial changes. 2024-04-30 Added a link to Network Interface Statistics. 2023-09-14 Added a link to TLS For Accessory Developers. 2023-07-23 First posted.

This issue has cropped up many times here on DevForums. Someone recently opened a DTS tech support incident about it, and I used that as an opportunity to post a definitive response here. If you have questions or comments about this, start a new thread and tag it with Network so that I see it. Share and Enjoy — Quinn “The Eskimo!” @ Developer Technical Support @ Apple let myEmail = "eskimo" + "1" + "@" + "apple.com" iOS Network Signal Strength The iOS SDK has no general-purpose API that returns Wi-Fi or cellular signal strength in real time. Given that this has been the case for more than 10 years, it’s safe to assume that it’s not an accidental omission but a deliberate design choice. For information about the Wi-Fi APIs that are available on iOS, see TN3111 iOS Wi-Fi API overview. Network performance Most folks who ask about this are trying to use the signal strength to estimate network performance. This is a technique that I specifically recommend against. That’s because it produces both false positives and false negatives: The network signal might be weak and yet your app has excellent connectivity. For example, an iOS device on stage at WWDC might have terrible WWAN and Wi-Fi signal but that doesn’t matter because it’s connected to the Ethernet. The network signal might be strong and yet your app has very poor connectivity. For example, if you’re on a train, Wi-Fi signal might be strong in each carriage but the overall connection to the Internet is poor because it’s provided by a single over-stretched WWAN. The only good way to determine whether connectivity is good is to run a network request and see how it performs. If you’re issuing a lot of requests, use the performance of those requests to build a running estimate of how well the network is doing. Indeed, Apple practices what we preach here: This is exactly how HTTP Live Streaming works. Remember that network performance can change from moment to moment. The user’s train might enter or leave a tunnel, the user might step into a lift, and so on. If you build code to estimate the network performance, make sure it reacts to such changes. Keeping all of the above in mind, iOS 26 beta has two new APIs related to this issue: Network framework now offers a linkQuality property. See this post for my take on how to use this effectively. The WirelessInsights framework can notify you of anticipated WWAN condition changes. But what about this code I found on the ’net? Over the years various folks have used various unsupported techniques to get around this limitation. If you find code on the ’net that, say, uses KVC to read undocumented properties, or grovels through system logs, or walks the view hierarchy of the status bar, don’t use it. Such techniques are unsupported and, assuming they haven’t broken yet, are likely to break in the future. But what about Hotspot Helper? Hotspot Helper does have an API to read Wi-Fi signal strength, namely, the signalStrength property. However, this is not a general-purpose API. Like the rest of Hotspot Helper, this is tied to the specific use case for which it was designed. This value only updates in real time for networks that your hotspot helper is managing, as indicated by the isChosenHelper property. But what about MetricKit? MetricKit is so cool. Amongst other things, it supports the MXCellularConditionMetric payload, which holds a summary of the cellular conditions while your app was running. However, this is not a real-time signal strength value. But what if I’m working for a carrier? This post is about APIs in the iOS SDK. If you’re working for a carrier, discuss your requirements with your carrier’s contact at Apple. Revision History 2025-07-02 Updated to cover new features in the iOS 16 beta. Made other minor editorial changes. 2022-12-01 First posted.

Hello, How long does it usually take for a URL Filter request to be reviewed? It's been 2.5 weeks since we submitted the request form but we haven't received any feedback yet. Just in case, the request ID is D3633USVZZ

HI, I am currently developing an app that utilizes Wi-Fi Aware. According to the Wi-Fi Aware framework examples and the WWDC25 session on Wi-Fi Aware, discovery is handled using DevicePairingView and DevicePicker from the DeviceDiscoveryUI module. However, these SwiftUI views present their connection UI modally when tapped. My app's design requires the ability to control the presentation of this UI programmatically, rather than relying on a user tap. While inspecting the DeviceDiscoveryUI module, I found DDDevicePairingViewController and DDDevicePickerViewController, which appear to be the UIViewController counterparts to the SwiftUI views. The initializer for DDDevicePairingViewController accepts a ListenerProvider, so it seems I can pass the same ListenerProvider instance that is used with the DevicePairingView. However, the initializer for DDDevicePickerViewController requires an NWBrowser.Descriptor, which seems incompatible with the parameters used for the SwiftUI DevicePicker. I have two main questions: (1) Can DDDevicePairingViewController and DDDevicePickerViewController be officially used for Wi-Fi Aware pairing? (2) Are there any plans to provide more customization or programmatic control over the DevicePairingView and DevicePicker (for example, allowing us to trigger their modal presentation programmatically)? Thank you.

On "Accessory Interface Specification CarPlay Addendum R10", it says that it is recommended that the accessory uses a MIMO (2x2) hardware configuration, does this imply that WiFi 5 and SISO (1X1) will be phased out in the near future? When will WiFi 6 MIMO (2x2) become mandatory? On "Accessory Interface Specification CarPlay Addendum R10", it says that Spatial Audio is mandatory. However, for aftermarket in-vehicle infotainment (IVI) system due to the number of speakers are less than 6, is it allowed not to support spatial audio for this type of aftermarket IVI system?

Hi there, We’re developing a companion app for a smart home product that communicates over the user’s local network. To provision the device, it initially creates its own Wi-Fi network. The user joins this temporary network and enters their home Wi-Fi credentials via our app. The app then sends those credentials directly to the device, which stores them and connects to the local network for normal operation. We’re using AccessorySetupKit to discover nearby devices (via SSID prefix) and NEHotspotManager to join the accessory’s Wi-Fi network once the user selects it. This workflow works well in general. However, we’ve encountered a problem: if the user factory-resets the accessory, or needs to restart setup (for example, after entering the wrong Wi-Fi password), the device no longer appears in the accessory picker. In iOS 18, we were able to work around this by calling removeAccessory() after the device is selected. This forces the picker to always display the accessory again. But in iOS 26, a new confirmation dialog now appears when calling removeAccessory(), which confuses users during setup. We’re looking for a cleaner way to handle this scenario — ideally a way to make the accessory rediscoverable without prompting the user to confirm removal. Thanks for your time and guidance.

Hello, Our app uses Network Extension / Packet Tunnel Provider to establish VPN connections on macOS and iOS. We have observed that after creating a utun device and adding any IPv4 routes (NEPacketTunnelNetworkSettings.IPv4Settings), the OS automatically adds several host routes via utun to services such as Akamai, Apple Push, etc. These routes appear to correspond to TCP flows that were active at the moment the VPN connection was established. When a particular TCP flow ends, the corresponding host route is deleted. We understand this is likely intended to avoid breaking existing TCP connections. However, we find the behavior of migrating existing TCP flows to the new utun interface simply because any IPv4 route is added somewhat questionable. This approach would make sense in a "full-tunnel" scenario — for example, when all IPv4 traffic (e.g., 0.0.0.0/0) is routed through the tunnel — but not necessarily in a "split-tunnel" configuration where only specific IPv4 routes are added. Is there any way to control or influence this behavior? Would it be possible for FlowDivert to differentiate between full-tunnel and split-tunnel cases, and only preserve existing TCP flows via utun in the full-tunnel scenario? Thank you.

General: Forums subtopic: App & System Services > Networking DevForums tag: Network Extension Network Extension framework documentation Routing your VPN network traffic article Filtering traffic by URL sample code Filtering Network Traffic sample code TN3120 Expected use cases for Network Extension packet tunnel providers technote TN3134 Network Extension provider deployment technote TN3165 Packet Filter is not API technote Network Extension and VPN Glossary forums post Debugging a Network Extension Provider forums post Exporting a Developer ID Network Extension forums post Network Extension Framework Entitlements forums post Network Extension vs ad hoc techniques on macOS forums post Network Extension Provider Packaging forums post NWEndpoint History and Advice forums post Extra-ordinary Networking forums post Wi-Fi management: Wi-Fi Fundamentals forums post TN3111 iOS Wi-Fi API overview technote How to modernize your captive network developer news post iOS Network Signal Strength forums post See also Networking Resources. Share and Enjoy — Quinn “The Eskimo!” @ Developer Technical Support @ Apple let myEmail = "eskimo" + "1" + "@" + "apple.com"

Is Apple's Wi-Fi Aware certified by the Wi-Fi Alliance? Is there any non-compliance of Apple's Wi-Fi Aware with the Wi-Fi Alliance standards? Does Apple have a roadmap to switch AWDL to Wi-Fi Aware? Does Apple have plans to adopt Wi-Fi Aware in Mac computers?

Hello, I have a few questions regarding URL Filter (iOS 26) and Content Filter Providers. URL Filter According to the WWDC26 video, URL Filter appears to be available for both consumer and enterprise deployments. This seems consistent with the classic Network Extension Provider Deployment documentation (TN3134 – August 2025), where no specific deployment restriction is mentioned. However, a more recent document (Apple Platform Deployment, September 2025) indicates the following for URL Filter: “Requires supervision on iPhone, iPad and Mac” (with a green checkmark). 👉 My question: Is URL Filter actually available for consumer use on non-supervised iPhones (deployed on Testflight and AppStore), or is supervision now required? Content Filter Providers From past experience, I remember that Content Filter Providers were only available on supervised devices. Based on the current documentation, I am questioning their usability in a consumer context, i.e. on non-supervised iPhones. In the Network Extension Provider Deployment documentation, it is stated that this is a Network Extension and that, since iOS 16, it is a “per-app on managed device” restriction. In the more recent Apple Platform Deployment document, it states for iPhone and iPad: “App needs to be installed on the user’s iOS and iPadOS device and deletion can be prevented if the device is supervised.” 👉 My understanding: Supervised device: The Content Filter Provider is installed via a host application that controls enabling/disabling the filter, and the host app can be prevented from being removed thanks to supervision. Non-supervised device: The Content Filter Provider is also installed via a host application that controls enabling/disabling the filter, but the app can be removed by the user, which would remove the filter. 👉 My question: Can Content Filter Providers be used in a consumer context on non-supervised iPhones (deployed on Testflight and AppStore), accepting that the user can uninstall the host app (and therefore remove the filter)? Thank you in advance for your feedback. Sources: TN3134 => TN3134: Network Extension provider deployment | Apple Developer Documentation Apple Platform Deployment / Filter content for Apple devices => https://support.apple.com/en-gb/guide/deployment/dep1129ff8d2/1/web/1.0

Hi all, I work on a smart product that, for setup, uses a captive portal to allow users to connect and configure the device. It emits a WiFi network and runs a captive portal - an HTTP server operates at 10.0.0.1, and a DNS server responds to all requests with 10.0.0.1 to direct "any and all" request to the server. When iOS devices connect, they send a request to captive.apple.com/hotspot-detect.html; if it returns success, that means they're on the internet; if not, the typical behavior in the past has been to assume you're connected to a captive portal and display what's being served. I serve any requests to /hotspot-detect.html with my captive portal page (index.html). This has worked reliably on iOS18 for a long time (user selects my products WiFi network, iOS detects portal and opens it). But almost everyone who's now trying with iOS26 is having the "automatic pop up" behavior fail - usually it says "Error opening page - Hotspot login cannot open the page because the network connection was lost." However, if opening safari and navigating to any URL (or 10.0.0.1) the portal loads - it's just the iOS auto-detect and open that's not working iOS18 always succeeds; iOS26 always fails. Anybody have any idea what changes may have been introduced in iOS26 on this front, or anything I can do to help prompt or coax iOS26 into loading the portal? It typically starts reading, but then stops mid-read.

I've been able to run this sample project with the PIRServer. But the urls are still not blocked. https://developer.apple.com/documentation/networkextension/filtering-traffic-by-url https://github.com/apple/pir-service-example I got this on the log Received filter status change: <FilterStatus: 'running'>

Hello, I understand that to discover and pair a device or accessory with Wi-Fi Aware, we can use either the DeviceDiscoveryUI or AccessorySetupKitUI frameworks. During the pairing process, both frameworks prompt the user to enter a pairing code. Is this step mandatory? What alternatives exist for devices or accessories that don't have a way to communicate a pairing code to the user (for example, devices or accessories without a display or voice capability)? Best regards, Gishan