What is the best way to detect if the Wifi is being used for Wireless Carplay or is just a normal network interface?

Hello all, Does anyone know how long it will take Apple to approve multicast entitlement approval after the Apple form is submitted? Any input would be appreciated. Thank you Allyson

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

In my app I have Local Push connectivity for local push notifications. My app has proper entitlment granted by Apple and NEAppPushProvider was working perfectly on older iOS versions before iOS26. The problem I faced with iOS26: when i enable VPN - NEAppPushProvider stops with reason /** @const NEProviderStopReasonNoNetworkAvailable There is no network connectivity. */ case noNetworkAvailable = 3. But device is still connected to proper SSID that is included to matchSSIDs. I discovered it only happens if my VPN config file include this line redirect-gateway def1 without that line NEAppPushProvider works as expected with enabled VPN. I use OpenVPN app. Is it a bug of iOS26 or I need some additional setup? Please help!

I am running a full-tunnel VPN using a Packet Tunnel Provider. During VPN setup, we configure DNS setting with specific DNS servers for all domains to be used by the tunnel. However, our project requires DNS resolution for every domain from both the VPN-provided DNS servers and the ISP’s DNS servers. When I attempt to use c-ares or other third-party libraries to resolve domains via the ISP DNS servers, these libraries only detect and use the VPN DNS servers instead. As a result, all queries fail. Is there a way on iOS to programmatically determine the ISP DNS servers while a full-tunnel VPN is active, or a system API that allows DNS queries to be explicitly resolved using the ISP’s DNS servers?

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.

The path from Network Extension’s in-provider networking APIs to Network framework has been long and somewhat rocky. The most common cause of confusion is NWEndpoint, where the same name can refer to two completely different types. I’ve helped a bunch of folks with this over the years, and I’ve decided to create this post to collect together all of those titbits. If you have questions or comments, please put them in a new thread. Put it 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" NWEndpoint History and Advice A tale that spans three APIs, two languages, and ten years. The NWEndpoint type has a long and complex history, and if you’re not aware of that history you can bump into weird problems. The goal of this post is to explain the history and then offer advice on how to get around specific problems. IMPORTANT This post focuses on NWEndpoint, because that’s the type that causes the most problems, but there’s a similar situation with NWPath. The History In iOS 9 Apple introduced the Network Extension (NE) framework, which offers a convenient way for developers to create a custom VPN transport. Network Extension types all have the NE prefix. Note I’m gonna use iOS versions here, just to keep the text simple. If you’re targeting some other platform, use this handy conversion table: iOS | macOS | tvOS | watchOS | visionOS --- + ----- + ---- + ------- + -------- 9 | 10.11 | 9 | 2 | - 12 | 10.14 | 12 | 5 | - 18 | 15 | 18 | 11 | 2 At that time we also introduced in-provider networking APIs. The idea was that an NE provider could uses these Objective-C APIs to communicate with its VPN server, and thereby avoiding a bunch of ugly BSD Sockets code. The in-provider networking APIs were limited to NE providers. Specifically, the APIs to construct an in-provider connection were placed on types that were only usable within an NE provider. For example, a packet tunnel provider could create a NWTCPConnection object by calling -createTCPConnectionToEndpoint:enableTLS:TLSParameters:delegate:] and -createTCPConnectionThroughTunnelToEndpoint:enableTLS:TLSParameters:delegate:, which are both methods on NEPacketTunnelProvider. These in-provider networking APIs came with a number of ancillary types, including NWEndpoint and NWPath. At the time we thought that we might promote these in-provider networking APIs to general-purpose networking APIs. That’s why the APIs use the NW prefix. For example, it’s NWTCPConnection, not NETCPConnection. However, plans changed. In iOS 12 Apple shipped Network framework as our recommended general-purpose networking API. This actually includes two APIs: A Swift API that follows Swift conventions, for example, the connection type is called NWConnection A C API that follows C conventions, for example, the connection type is called nw_connection_t These APIs follow similar design patterns to the in-provider networking API, and thus have similar ancillary types. Specifically, there are an NWEndpoint and nw_endpoint_t types, both of which perform a similar role to the NWEndpoint type in the in-provider networking API. This was a source of some confusion in Swift, because the name NWEndpoint could refer to either the Network framework type or the Network Extension framework type, depending on what you’d included. Fortunately you could get around this by qualifying the type as either Network.NWEndpoint or NetworkExtension.NWEndpoint. The arrival of Network framework meant that it no longer made sense to promote the in-provider networking APIs to general-purposes networking APIs. The in-provider networking APIs were on the path to deprecation. However, deprecating these APIs was actually quite tricky. Network Extension framework uses these APIs in a number of interesting ways, and so deprecating them required adding replacements. In addition, we’d needed different replacements for Swift and Objective-C, because Network framework has separate APIs for Swift and C-based languages. In iOS 18 we tackled that problem head on. To continue the NWTCPConnection example above, we replaced: -createTCPConnectionToEndpoint:enableTLS:TLSParameters:delegate:] with nw_connection_t -createTCPConnectionThroughTunnelToEndpoint:enableTLS:TLSParameters:delegate: with nw_connection_t combined with a new virtualInterface property on NEPacketTunnelProvider Of course that’s the Objective-C side of things. In Swift, the replacement is NWConnection rather than nw_connection_t, and the type of the virtualInterface property is NWInterface rather than nw_interface_t. But that’s not the full story. For the two types that use the same name in both frameworks, NWEndpoint and NWPath, we decided to use this opportunity to sort out that confusion. To see how we did that, check out the <NetworkExtension/NetworkExtension.apinotes> file in the SDK. Focusing on NWEndpoint for the moment, you’ll find two entries: … - Name: NWEndpoint SwiftPrivate: true … SwiftVersions: - Version: 5.0 … - Name: NWEndpoint SwiftPrivate: false … The first entry applies when you’re building with the Swift 6 language mode. This marks the type as SwiftPrivate, which means that Swift imports it as __NWEndpoint. That frees up the NWEndpoint name to refer exclusively to the Network framework type. The second entry applies when you’re building with the Swift 5 language mode. It marks the type as not SwiftPrivate. This is a compatible measure to ensure that code written for Swift 5 continues to build. The Advice This sections discusses specific cases in this transition. NWEndpoint and NWPath In Swift 5 language mode, NWEndpoint and NWPath might refer to either framework, depending on what you’ve imported. Add a qualifier if there’s any ambiguity, for example, Network.NWEndpoint or NetworkExtension.NWEndpoint. In Swift 6 language mode, NWEndpoint and NWPath always refer to the Network framework type. Add a __ prefix to get to the Network Extension type. For example, use NWEndpoint for the Network framework type and __NWEndpoint for the Network Extension type. Direct and Through-Tunnel TCP Connections in Swift To create a connection directly, simply create an NWConnection. This support both TCP and UDP, with or without TLS. To create a connection through the tunnel, replace code like this: let c = self.createTCPConnectionThroughTunnel(…) with code like this: let params = NWParameters.tcp params.requiredInterface = self.virtualInterface let c = NWConnection(to: …, using: params) This is for TCP but the same basic process applies to UDP. UDP and App Proxies in Swift If you’re building an app proxy, transparent proxy, or DNS proxy in Swift and need to handle UDP flows using the new API, adopt the NEAppProxyUDPFlowHandling protocol. So, replace code like this: class AppProxyProvider: NEAppProxyProvider { … override func handleNewUDPFlow(_ flow: NEAppProxyUDPFlow, initialRemoteEndpoint remoteEndpoint: NWEndpoint) -> Bool { … } } with this: class AppProxyProvider: NEAppProxyProvider, NEAppProxyUDPFlowHandling { … func handleNewUDPFlow(_ flow: NEAppProxyUDPFlow, initialRemoteFlowEndpoint remoteEndpoint: NWEndpoint) -> Bool { … } } Creating a Network Rule To create an NWHostEndpoint, replace code like this: let ep = NWHostEndpoint(hostname: "1.2.3.4", port: "12345") let r = NENetworkRule(destinationHost: ep, protocol: .TCP) with this: let ep = NWEndpoint.hostPort(host: "1.2.3.4", port: 12345) let r = NENetworkRule(destinationHostEndpoint: ep, protocol: .TCP) Note how the first label of the initialiser has changed from destinationHost to destinationHostEndpoint.

multicast sockets fail to send/receive on macosx, errno 65 "no route to host". Wireshark and Terminal.app (which have root privileges) both show incoming multicast traffic just fine. Normal UDP broadcast sockets have no problems. Toggling the Security&Privacy -> Local Network setting may fix the problem for some Users. There is no pattern for when multicast socket fails. Sometimes, recreating the sockets fix the problem. Restart the app, sometimes multicast fails, sometimes success (intermittent, no pattern). Reboot machine (intermittent fail) Create a fresh new user on machine, install single version of app, give app permission. (intermittent fail, same as above). We have all the normal entitlements / notarized app. Similar posts here see FB16923535, Related to FB16512666 https://forum.xojo.com/t/udp-multicast-receive-on-mac-failing-intermittant/83221 see my post from 2012 "distinguishing between SENDING sockets and RECEIVING sockets" for source code example of how we bind multicast sockets. Our other socket code is standard "Stevens, et al." code. The bind() is the call that fails in this case. https://stackoverflow.com/questions/10692956/what-does-it-mean-to-bind-a-multicast-udp-socket . Note that this post from 2012 is still relevant, and that it is a workaround to a longstanding Apple bug that was never fixed. Namely, "Without this fix, multicast sending will intermittently get sendto() errno 'No route to host'. If anyone can shed light on why unplugging a DHCP gateway causes Mac OS X multicast SENDING sockets to get confused, I would love to hear it." This may be a hint as to the underlying bug that Apple really needs to fix, but if it's not, then please Apple, fix the Sequoia bug first. These are probably different bugs because in one case, sendto() fails when a socket becomes "unbound" after you unplug an unrelated network cable. In this case, bind() fails, so sendto() is never even called. Note, that we have also tried to use other implementations for network discovery, including Bonjour, CFNetwork, etc. Bonjour fails intermittently, and also suffers from both bugs mentioned above, amongst others.

I am trying to activate an application which sends my serial number to a server. The send is being blocked. The app is signed but not sandboxed. I am running Sequoia on a recent iMac. My network firewall is off and I do not have any third party virus software. I have selected Allow Applications from App Store & Known Developers. My local network is wifi using the eero product. There is no firewall or virus scanning installed with this product. Under what circumstances will Mac OS block outgoing internet connections from a non-sandboxed app? How else could the outgoing connection be blocked?

Here’s the formatted summary in English for your issue submission: Issue Summary We are activating a Network Extension system extension (filter-data) from a signed and notarized macOS app. Activation consistently fails with the following error: Error Message: OSSystemExtensionErrorDomain code=4 Extension not found in App bundle. Unable to find any matched extension with identifier: com.seaskylight.yksmacos.ExamNetFilter.data At the same time, sysextd logs show: no policy, cannot allow apps outside /Applications However, our host app and executable paths are already under /Applications, and the extension bundle physically exists in the expected app bundle location. Environment Information macOS: Darwin 25.4.0 Host App: /Applications/xxx.app Host Bundle ID: com.seaskylight.yksmacos System Extension Bundle ID: com.seaskylight.yksmacos.ExamNetFilter.data Team ID: BVU65MZFLK Device Management: Enrolled via DEP: No MDM Enrollment: No Reproduction Steps Install the host app to /Applications. Launch the host app via Finder or using the command: open -a "/Applications/xxx.app" Trigger OSSystemExtensionRequest activationRequestForExtension for: com.seaskylight.yksmacos.ExamNetFilter.data. Observe failure callback (code=4). Collect logs: log show --last 2m --style compact --info --debug --predicate 'process == "sysextd"' Check extension status using: systemextensionsctl list (shows 0 extension(s)) Observed Results sysextd client activation request for com.seaskylight.yksmacos.ExamNetFilter.data attempts to realize extension with identifier com.seaskylight.yksmacos.ExamNetFilter.data. Log indicates: no policy, cannot allow apps outside /Applications App-side Diagnostics (captured at failure) PID: 3249 Bundle Path: /Applications/xxx.app Real Path: /Applications/xxx.app Exec Path: /Applications/xxx.app/Contents/MacOS/xxx Real Exec Path: /Applications/xxx.app/Contents/MacOS/xxx Ext Path: /Applications/xxx.app/Contents/Library/SystemExtensions/ExamNetFilterData.systemextension Ext Exists: true Running From Helper: false Error Callback: NSError{domain=OSSystemExtensionErrorDomain code=4 desc=Extension not found in App bundle...} Additional Validation We reproduced the same failure using a minimal native host app (SysExtProbe) in /Applications that only submits the activation request for the same extension identifier. It also fails with OSSystemExtensionErrorDomain code=4, indicating this is not specific to Electron app logic. Signing / Packaging Notes Host app and system extension are signed with the same Team ID (BVU65MZFLK). System extension bundle exists under: /Applications/xxx.app/Contents/Library/SystemExtensions/ExamNetFilterData.systemextension Extension Info.plist contains bundle id: com.seaskylight.yksmacos.ExamNetFilter.data Host app includes NSSystemExtensionUsageDescription. Questions for DTS In non-MDM personal-device scenarios, what exact conditions trigger sysextd to emit: no policy, cannot allow apps outside /Applications even when both bundlePath and realpath are in /Applications? Can code=4 (“Extension not found in App bundle”) be returned for policy/state reasons even when the extension bundle is present and the identifier matches? Are there known sysextd policy/cache states that cause this behavior, and what is the recommended recovery procedure? Feel free to copy and paste this summary for your submission. If you need any further modifications or assistance, let me know!

I'm developing a lighting control app for iOS that receives Art-Net (UDP port 6454) and sACN (UDP port 5568) packets from a lighting console and relays commands to BLE wristbands with LEDs. This is used in live event production — the participant locks their phone while in a show and expects lighting control to continue uninterrupted. The problem UDP receive stops reliably ~30 seconds after the screen locks. I understand this is by design - iOS suspends apps in the background. However, I'm trying to understand if any supported path exists for this use case. What I've already tried UIRequiresPersistentWiFi = true - helps with Wi-Fi association but doesn't prevent app suspension Silent AVAudioEngine loop with UIBackgroundModes: audio - keeps the app alive, works in testing, but risks App Store rejection and feels like an abuse of the audio background mode NWListener (Network framework) on the UDP port - same suspension behaviour Socket rebind on applicationWillEnterForeground - recovers after resume but doesn't prevent dropout What I'm asking Is there any supported background mode or entitlement for sustained UDP receive in a professional/enterprise context? (Similar to how VoIP apps get the voip background mode for sustained network activity.) Is the silent audio workaround considered acceptable for App Store distribution in a professional tools context, or will it be rejected? Is NEAppProxyProvider or another Network Extension a viable path, and if so does it require a special entitlement? Test project I have a minimal Xcode project (~130 lines) demonstrating the issue — NWListener on port 6454, packet counter, staleness timer, and silent audio toggle. I can share the test code. STEPS TO REPRODUCE In Xcode (one-time setup): Select the UDPBackgroundTest target → Signing & Capabilities → set your Team Plug in your iPhone → select it as the run destination Build & run — confirm packets appear on screen when you run 'send_test_udp.py' Lock the phone and observe the dropout Test: Open the app and run 'python3 send_test_udp.py 192.168.0.XXX' The app counts up the packages, they match the python output. 1 packet per second. lock screen & and wait 10 seconds unlock phone an see the numbers are 10 packets off

Questions about FTP crop up from time-to-time here on DevForums. In most cases I write a general “don’t use FTP” response, but I don’t have time to go into all the details. I’ve created this post as a place to collect all of those details, so I can reference them in other threads. IMPORTANT Apple’s official position on FTP is: All our FTP APIs have been deprecated, and you should avoid using deprecated APIs. Apple has been slowly removing FTP support from the user-facing parts of our system. The most recent example of this is that we removed the ftp command-line tool in macOS 10.13. You should avoid the FTP protocol and look to adopt more modern alternatives. The rest of this post is an informational explanation of the overall FTP picture. This post is locked so I can keep it focused. If you have questions or comments, please do create a new thread in the App & System Services > Networking subtopic and I’ll respond there. Don’t Use FTP FTP is a very old and very crufty protocol. Certain things that seem obvious to us now — like being able to create a GUI client that reliably shows a directory listing in a platform-independent manner — aren’t possible to do in FTP. However, by far the biggest problem with FTP is that it provides no security [1]. Specifically, the FTP protocol: Provides no on-the-wire privacy, so anyone can see the data you transfer Provides no client-authenticates-server authentication, so you have no idea whether you’re talking to the right server Provides no data integrity, allowing an attacker to munge your data in transit Transfers user names and passwords in the clear Using FTP for anonymous downloads may be acceptable (see the explanation below) but most other uses of FTP are completely inappropriate for the modern Internet. IMPORTANT You should only use FTP for anonymous downloads if you have an independent way to check the integrity of the data you’ve downloaded. For example, if you’re downloading a software update, you could use code signing to check its integrity. If you don’t check the integrity of the data you’ve downloaded, an attacker could substitute a malicious download instead. This would be especially bad in, say, the software update case. These fundamental problems with the FTP protocol mean that it’s not a priority for Apple. This is reflected in the available APIs, which is the subject of the next section. FTP APIs Apple provides two FTP APIs: All Apple platforms provide FTP downloads via URLSession. Most Apple platforms (everything except watchOS) support CFFTPStream, which allows for directory listings, downloads, uploads, and directory creation. All of these FTP APIs are now deprecated: URLSession was deprecated for the purposes of FTP in the 2022 SDKs (macOS 13, iOS 16, iPadOS 16, tvOS 16, watchOS 9) [2]. CFFTPStream was deprecated in the 2016 SDKs (macOS 10.11, iOS 9, iPadOS 9, tvOS 9). CFFTPStream still works about as well as it ever did, which is not particularly well. Specifically: There is at least one known crashing bug (r. 35745763), albeit one that occurs quite infrequently. There are clear implementation limitations — like the fact that CFFTPCreateParsedResourceListing assumes a MacRoman text encoding (r. 7420589) — that won’t be fixed. If you’re looking for an example of how to use these APIs, check out SimpleFTPSample. Note This sample hasn’t been updated since 2013 and is unlikely to ever be updated given Apple’s position on FTP. The FTP support in URLSession has significant limitations: It only supports FTP downloads; there’s no support for uploads or any other FTP operations. It doesn’t support resumable FTP downloads [3]. It doesn’t work in background sessions. That prevents it from running FTP downloads in the background on iOS. It’s only supported in classic loading mode. See the usesClassicLoadingMode property and the doc comments in <Foundation/NSURLSession.h>. If Apple’s FTP APIs are insufficient for your needs, you’ll need to write or acquire your own FTP library. Before you do that, however, consider switching to an alternative protocol. After all, if you’re going to go to the trouble of importing a large FTP library into your code base, you might as well import a library for a better protocol. The next section discusses some options in this space. Alternative Protocols There are numerous better alternatives to FTP: HTTPS is by far the best alternative to FTP, offering good security, good APIs on Apple platforms, good server support, and good network compatibility. Implementing traditional FTP operations over HTTPS can be a bit tricky. One possible way forward is to enable DAV extensions on the server. FTPS is FTP over TLS (aka SSL). While FTPS adds security to the protocol, which is very important, it still inherits many of FTP’s other problems. Personally I try to avoid this protocol. SFTP is a file transfer protocol that’s completely unrelated to FTP. It runs over SSH, making it a great alternative in many of the ad hoc setups that traditionally use FTP. Apple doesn’t have an API for either FTPS or SFTP, although on macOS you may be able to make some headway by invoking the sftp command-line tool. Share and Enjoy — Quinn “The Eskimo!” @ Developer Technical Support @ Apple let myEmail = "eskimo" + "1" + "@" + "apple.com" [1] In another thread someone asked me about FTP’s other problems, those not related to security, so let’s talk about that. One of FTP’s implicit design goals was to provide cross-platform support that exposes the target platform. You can think of FTP as being kinda like telnet. When you telnet from Unix to VMS, it doesn’t aim to abstract away VMS commands, so that you can type Unix commands at the VMS prompt. Rather, you’re expected to run VMS commands. FTP is (a bit) like that. This choice made sense back when the FTP protocol was invented. Folks were expecting to use FTP via a command-line client, so there was a human in the loop. If they ran a command and it produced VMS-like output, that was fine because they knew that they were FTPing into a VMS machine. However, most users today are using GUI clients, and this design choice makes it very hard to create a general GUI client for FTP. Let’s consider the simple problem of getting the contents of a directory. When you send an FTP LIST command, the server would historically run the platform native directory list command and pipe the results back to you. To create a GUI client you have to parse that data to extract the file names. Doing that is a serious challenge. Indeed, just the first step, working out the text encoding, is a challenge. Many FTP servers use UTF-8, but some use ISO-Latin-1, some use other standard encodings, some use Windows code pages, and so on. I say “historically” above because there have been various efforts to standardise this stuff, both in the RFCs and in individual server implementations. However, if you’re building a general client you can’t rely on these efforts. After all, the reason why folks continue to use FTP is because of it widespread support. [2] To quote the macOS 13 Ventura Release Notes: FTP is deprecated for URLSession and related APIs. Please adopt modern secure networking protocols such as HTTPS. (92623659) [3] Although you can implement resumable downloads using the lower-level CFFTPStream API, courtesy of the kCFStreamPropertyFTPFileTransferOffset property. Revision History 2025-10-06 Explained that URLSession only supports FTP in classic loading mode. Made other minor editorial changes. 2024-04-15 Added a footnote about FTP’s other problems. Made other minor editorial changes. 2022-08-09 Noted that the FTP support in URLSession is now deprecated. Made other minor editorial changes. 2021-04-06 Fixed the formatting. Fixed some links. 2018-02-23 First posted.

Our app is developed for iOS, but some users also run it on macOS (as an iOS app via Apple Silicon). The app requires local network permission, which works perfectly on iOS. Previously, the connection also worked fine on macOS, but since the recent macOS update, the app can no longer connect to our device. Additionally, our app on macOS doesn't prompt for local network permission at all, whereas it does on iOS. Is this a known issue with iOS apps running on macOS? Has anyone else experienced this problem, or is there a workaround? Any help would be appreciated!

Hi everyone 👋 As a network engineer and indie iOS developer, I couldn’t find a lightweight mobile tool that fully supports IPv4/IPv6 dual-stack diagnostics — so I built NetToolbox -All-In-One Utility for engineers, DevOps, and developers. Here are its core features that solve real mobile networking pain points: One-Click Full Diagnostics: Integrates ping, traceroute, and multi-type DNS queries (A/AAAA/CNAME) — no need to switch between apps IPv4/IPv6 Dual-Stack Support: Seamlessly works in IPv6-only networks, with the ability to test connectivity differences between dual-stack environments LAN Device Scanning: Quickly identifies all devices on the same network segment and checks port availability Offline Functionality: Diagnostic logic is stored locally, enabling LAN troubleshooting without an internet connection Lightweight Design: 5MB install size, no storage bloat, and low power consumption during operation Dark Mode Support: Tailored for developers who work late at night During development, I leveraged Apple Intelligence alongside Claude Code and Gemini 3 to accelerate the process, optimize iOS native networking stack adaptation and local storage logic, and significantly boost development efficiency. I’d love to hear from the community: What must-have features are missing from mobile network diagnostic tools? Do you have experience optimizing iOS workflows with Apple Intelligence? 👉 You can try the app here: https://apps.apple.com/us/app/nettoolbox-all-in-one-utility/id6757392404 Feedback is highly appreciated — I’ll keep iterating to make it better! 🚀

Summary We are activating a Network Extension system extension (filter-data) from a signed and notarized macOS app. Activation consistently fails with: OSSystemExtensionErrorDomain code=4 Extension not found in App bundle. Unable to find any matched extension with identifier: com.seaskylight.yksmacos.ExamNetFilter.data At the same time, sysextd logs: no policy, cannot allow apps outside /Applications However, our host app and executable real paths are already under /Applications, and the extension bundle physically exists in the expected app bundle location. Environment macOS: Darwin 25.4.0 Host app: /Applications/xxx.app Host bundle id: com.seaskylight.yksmacos System extension bundle id: com.seaskylight.yksmacos.ExamNetFilter.data Team ID: BVU65MZFLK Device management: Enrolled via DEP: No MDM enrollment: No Reproduction Steps Install host app to /Applications. Launch host app via Finder or: open -a "/Applications/xxx.app" Trigger OSSystemExtensionRequest activationRequestForExtension for: com.seaskylight.yksmacos.ExamNetFilter.data Observe failure callback (code=4). Collect logs: log show --last 2m --style compact --info --debug --predicate 'process == "sysextd"' systemextensionsctl list (shows 0 extension(s)) Observed Results sysextd client activation request for com.seaskylight.yksmacos.ExamNetFilter.data attempting to realize extension with identifier com.seaskylight.yksmacos.ExamNetFilter.data no policy, cannot allow apps outside /Applications App-side diagnostics (captured at failure) pid=3249 bundlePath=/Applications/xxx.app bundlePathReal=/Applications/xxx.app execPath=/Applications/xxx.app/Contents/MacOS/xxx execPathReal=/Applications/xxx.app/Contents/MacOS/xxx extPath=/Applications/xxx.app/Contents/Library/SystemExtensions/ExamNetFilterData.systemextension extExists=true runningFromHelper=false Error callback NSError{domain=OSSystemExtensionErrorDomain code=4 desc=Extension not found in App bundle...} Additional Validation We reproduced the same failure using a minimal native host app (SysExtProbe) in /Applications that only submits the activation request for the same extension identifier. It also fails with OSSystemExtensionErrorDomain code=4, indicating this is not specific to Electron app logic. Signing / Packaging Notes Host app and system extension are signed with the same Team ID (BVU65MZFLK). System extension bundle exists under: /Applications/xxx.app/Contents/Library/SystemExtensions/ExamNetFilterData.systemextension Extension Info.plist contains bundle id: com.seaskylight.yksmacos.ExamNetFilter.data Host app includes NSSystemExtensionUsageDescription. Questions for DTS In non-MDM personal-device scenarios, what exact conditions trigger sysextd to emit: no policy, cannot allow apps outside /Applications even when both bundlePath and realpath are in /Applications? Can code=4 (“Extension not found in App bundle”) be returned for policy/state reasons even when extension bundle is present and identifier matches? Are there known sysextd policy/cache states that cause this behavior, and what is the recommended recovery procedure?

Starting in iOS 26.4, PushKit has introduced a new "didReceiveIncomingVoIPPushWithPayload" delegate, making it explicit whether or not an app is required to report a call for any given push. The new delegate passes in a PKVoIPPushMetadata object which includes a "mustReport" property. We have not documented the exact criteria that will cause a mustReport to return false, but those criteria currently include: The app being in the foreground at the point the push is received. The app being on an active call at the point the push is received. The system determines that delivery delays have made the call old enough that it may no longer be viable. When mustReport is false, apps should call the PushKit completion handler (as they previously have) but are otherwise not required to take any other action. __ Kevin Elliott DTS Engineer, CoreOS/Hardware

Greetings, According to Apple's Wi-Fi Aware documentation (https://developer.apple.com/documentation/wifiaware) the Wi-Fi Aware APIs can be used only with peer devices that have been paired. Pairing can be performed using AccessorySetupKit or DeviceDiscoveryUI. Unfortunately, the sample code for Wi-Fi Aware doesn't include either of these APIs. (https://developer.apple.com/documentation/wifiaware/building-peer-to-peer-apps) Looking at the sample code for AccessorySetupKit (https://developer.apple.com/documentation/accessorysetupkit/setting-up-and-authorizing-a-bluetooth-accessory) there is only an example using Bluetooth. And the AccessorySetupKit APIs don't yet document how Wi-Fi Aware is used or how one sets up the Info.plist with the appropriate keys. Can Apple update its example code to fill in these gaps or point me to documentation that can fill in these gaps? It is hard to develop an understanding of the capabilities of these APIs when they are so poorly documented. Thanks for any help, Smith

For important background information, read Extra-ordinary Networking before reading this. Share and Enjoy — Quinn “The Eskimo!” @ Developer Technical Support @ Apple let myEmail = "eskimo" + "1" + "@" + "apple.com" Network Interface APIs Most developers don’t need to interact directly with network interfaces. If you do, read this post for a summary of the APIs available to you. Before you read this, read Network Interface Concepts. Interface List The standard way to get a list of interfaces and their addresses is getifaddrs. To learn more about this API, see its man page. A network interface has four fundamental attributes: A set of flags — These are packed into a CUnsignedInt. The flags bits are declared in <net/if.h>, starting with IFF_UP. An interface type — See Network Interface Type, below. An interface index — Valid indexes are greater than 0. A BSD interface name. For example, an Ethernet interface might be called en0. The interface name is shared between multiple network interfaces running over a given hardware interface. For example, IPv4 and IPv6 running over that Ethernet interface will both have the name en0. WARNING BSD interface names are not considered API. There’s no guarantee, for example, that an iPhone’s Wi-Fi interface is en0. You can map between the last two using if_indextoname and if_nametoindex. See the if_indextoname man page for details. An interface may also have address information. If present, this always includes the interface address (ifa_addr) and the network mask (ifa_netmask). In addition: Broadcast-capable interfaces (IFF_BROADCAST) have a broadcast address (ifa_broadaddr, which is an alias for ifa_dstaddr). Point-to-point interfaces (IFF_POINTOPOINT) have a destination address (ifa_dstaddr). Calling getifaddrs from Swift is a bit tricky. For an example of this, see QSocket: Interfaces. IP Address List Once you have getifaddrs working, it’s relatively easy to manipulate the results to build a list of just IP addresses, a list of IP addresses for each interface, and so on. QSocket: Interfaces has some Swift snippets that show this. Interface List Updates The interface list can change over time. Hardware interfaces can be added and removed, network interfaces come up and go down, and their addresses can change. It’s best to avoid caching information from getifaddrs. If thats unavoidable, use the kNotifySCNetworkChange Darwin notification to update your cache. For information about registering for Darwin notifications, see the notify man page (in section 3). This notification just tells you that something has changed. It’s up to you to fetch the new interface list and adjust your cache accordingly. You’ll find that this notification is sometimes posted numerous times in rapid succession. To avoid unnecessary thrashing, debounce it. While the Darwin notification API is easy to call from Swift, Swift does not import kNotifySCNetworkChange. To fix that, define that value yourself, calling a C function to get the value: var kNotifySCNetworkChange: UnsafePointer<CChar> { networkChangeNotifyKey() } Here’s what that C function looks like: extern const char * networkChangeNotifyKey(void) { return kNotifySCNetworkChange; } Network Interface Type There are two ways to think about a network interface’s type. Historically there were a wide variety of weird and wonderful types of network interfaces. The following code gets this legacy value for a specific BSD interface name: func legacyTypeForInterfaceNamed(_ name: String) -> UInt8? { var addrList: UnsafeMutablePointer<ifaddrs>? = nil let err = getifaddrs(&addrList) // In theory we could check `errno` here but, honestly, what are gonna // do with that info? guard err >= 0, let first = addrList else { return nil } defer { freeifaddrs(addrList) } return sequence(first: first, next: { $0.pointee.ifa_next }) .compactMap { addr in guard let nameC = addr.pointee.ifa_name, name == String(cString: nameC), let sa = addr.pointee.ifa_addr, sa.pointee.sa_family == AF_LINK, let data = addr.pointee.ifa_data else { return nil } return data.assumingMemoryBound(to: if_data.self).pointee.ifi_type } .first } The values are defined in <net/if_types.h>, starting with IFT_OTHER. However, this value is rarely useful because many interfaces ‘look like’ Ethernet and thus have a type of IFT_ETHER. Network framework has the concept of an interface’s functional type. This is an indication of how the interface fits into the system. There are two ways to get an interface’s functional type: If you’re using Network framework and have an NWInterface value, get the type property. If not, call ioctl with a SIOCGIFFUNCTIONALTYPE request. The return values are defined in <net/if.h>, starting with IFRTYPE_FUNCTIONAL_UNKNOWN. Swift does not import SIOCGIFFUNCTIONALTYPE, so it’s best to write this code in a C: extern uint32_t functionalTypeForInterfaceNamed(const char * name) { int fd = socket(AF_INET, SOCK_DGRAM, 0); if (fd < 0) { return IFRTYPE_FUNCTIONAL_UNKNOWN; } struct ifreq ifr = {}; strlcpy(ifr.ifr_name, name, sizeof(ifr.ifr_name)); bool success = ioctl(fd, SIOCGIFFUNCTIONALTYPE, &ifr) >= 0; int junk = close(fd); assert(junk == 0); if ( ! success ) { return IFRTYPE_FUNCTIONAL_UNKNOWN; } return ifr.ifr_ifru.ifru_functional_type; } Finally, TN3158 Resolving Xcode 15 device connection issues documents the SIOCGIFDIRECTLINK flag as a specific way to identify the network interfaces uses by Xcode for device connection traffic. Revision History 2025-12-10 Added info about SIOCGIFDIRECTLINK. 2023-07-19 First posted.

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 bit complicated to explain so bare with me. I am working on building an app that allows you to send real time video/camera captures from one Apple device to another. I am using a custom UDP protocol built on top of NWListener, NWBrowser, and NWConnection APIs. It works fine, but there are a few issues that seems to all be related to awdl: When transmitting via WiFi over the router (not using peer-to-peer), there are periodic interruptions when the wireless card on the device changes channels for awdl polling. This is resolved by changing the 5GHz WiFi channel on the router to channel 149 (or disabling AWDL altogether which is not really feasible). In order to work around number 1, I decided to build in an option to toggle/prefer peer-to-peer transmission in the app thinking that if everything goes over a peer-to-peer connection the jitter caused from the channel switching should go away. This also works, but with an important caveat. The default transmission is extremely choppy until you take an OS action that “elevates” the AWDL connection into “realtime” mode. I am using includePeerToPeer on the listener, browser, and connection as well as serviceClass interactiveVideo. For number 1, you can understand that asking users to change the channel on their router is not a great user experience, but the problem is the peer-to-peer connection workaround is also not great by default. For number 2, as an example of the behavior, I can send a stream from my Mac to my iPad over a peer-to-peer connection and it works but the video is very choppy until I move my cursor from my Mac to my iPad to trigger Universal Control. I captured the OS logs while doing this and can confirm that something happens to trigger “realtime” mode on the AWDL connection. After that, the streaming is totally smooth with zero latency. Some log samples: 2026-03-19 12:42:01.277968-0400 0x1ae294c Default 0x0 495 3 rapportd: (CoreUtils) [com.apple.rapport:CLinkD] Update client from UniversalControl:697 2026-03-19 12:42:01.278031-0400 0x1ae294c Default 0x0 495 0 rapportd: (CoreUtils) [com.apple.CoreUtils:AsyncCnx] CLinkCnx-6089: Connect start: 'CLink-ed3b9618b4e0._companion-link._tcp.local.%13' 2026-03-19 12:42:01.278149-0400 0x1ae294c Default 0x0 495 0 rapportd: (CoreUtils) [com.apple.CoreUtils:AsyncCnx] CLinkCnx-6089: Querying SRV CLink-ed3b9618b4e0._companion-link._tcp.local.%13 2026-03-19 12:42:01.279454-0400 0x1ae253a Info 0x0 382 0 wifip2pd: [com.apple.awdl:datapathInitiator] Created AWDLDatapathInitiator clink-ed3b9618b4e0._companion-link._tcp.local <To: 2e:f2:5a:15:76:52> 2026-03-19 12:42:01.279498-0400 0x1ae294c Default 0x0 495 0 rapportd: (CoreUtils) [com.apple.CoreUtils:AsyncCnx] CLinkCnx-6089: Resolving DNS f970afcc-1f1c-47af-a3f3-0236c9f9bbb0.local.%13 2026-03-19 12:42:01.279588-0400 0x1ae253a Default 0x0 382 0 wifip2pd: [com.apple.awdl:datapathInitiator] AWDLDatapathInitiator clink-ed3b9618b4e0._companion-link._tcp.local <To: 2e:f2:5a:15:76:52> was started 2026-03-19 12:42:01.282537-0400 0x1ae294c Default 0x0 495 0 rapportd: (Network) [com.apple.network:path] nw_path_evaluator_start [5C54D967-624D-4269-B080-6C7AE63218C7 IPv6#1e905043%awdl0.49154 generic, attribution: developer] path: satisfied (Path is satisfied), interface: awdl0[802.11], dns, uses wifi 2026-03-19 12:42:01.596450-0400 0x1ae253a Debug 0x0 382 0 wifip2pd: [com.apple.awdl:driver] Received event realtimeMode 2026-03-19 12:42:01.596589-0400 0x1ae253a Default 0x0 382 0 wifip2pd: [com.apple.awdl:interface] Realtime mode updated true I noticed that on iOS 26 and iPadOS 26 a realtime mode was added specifically to the Wi-Fi Aware API which I assume does what I want: https://developer.apple.com/documentation/wifiaware/waperformancemode/realtime, but I am looking for a solution that works with the existing network API and also on previous OS versions. I have already tried a lot of things, but is there any way to programmatically trigger “realtime” mode? For additional context, the goal here is to have extremely low latency that also works for gaming. The actual latency introduced in 1 is approximately 30-50ms around once a second… adding a buffer to the stream makes the video completely smooth, but the extra delay on the receiver end is not acceptable for this use case. Any help or ideas would be appreciated. I can’t easily share a reproduce case right now, and even if I could, getting multiple devices into the exact state along with the router configuration in order to reproduce is going to be pretty difficult anyway.