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Explore the networking protocols and technologies used by the device to connect to Wi-Fi networks, Bluetooth devices, and cellular data services.

Networking Documentation

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ipad通过转接口连接上有线网络之后,部分设备无法获取到IP地址
private static func getEthernetIPAddress(from interfaces: [String: String]) -> String? { // 常见虚拟以太网接口名(根据适配器型号可能不同) let poeEthernetInterfaces = ["en2", "en3", "en4", "en5", "eth0", "eth1"] for interfaceName in poeEthernetInterfaces { if let ethernetIP = interfaces[interfaceName], !ethernetIP.isEmpty { return ethernetIP } } return nil }//我们通过该方法去抓取有线网的IP地址,但是有的设备无法抓取到,怎样才能更准确的抓取到有线网络的IP地址
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139
Jan ’26
Content filtering
Hello team, Would this mean that content filters intended for all browsing can only be implemented for managed devices using MDM? My goal would be to create a content filtering app for all users, regardless of if their device is managed/supervised. thanks.
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101
Jan ’26
FYI: Network System extension, macOS update issue, loss of networking
This is just an FYI in case someone else runs into this problem. This afternoon (12 Dec 2025), I updated to macOS 26.2 and lost my network. The System Settings' Wi-Fi light was green and said it was connected, but traceroute showed "No route to host". I turned Wi-Fi on & off. I rebooted the Mac. I rebooted the eero network. I switched to tethering to my iPhone. I switched to physical ethernet cable. Nothing worked. Then I remembered I had a beta of an app with a network system extension that was distributed through TestFlight. I deleted the app, and networking came right back. I had this same problem ~2 years ago. Same story: app with network system extension + TestFlight + macOS update = lost network. (My TestFlight build might have expired, but I'm not certain) I don't know if anyone else has had this problem, but I thought I'd share this in case it helps.
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203
Jan ’26
`setTunnelNetworkSettings` errors in a packet tunnel provider.
We've received logs and have spuriously reproduced the following behavior: calls to setTunnelNetworkSettings completing with NETunnelProviderError where the code is networkSettingsInvalid, and the error domain string is empty. After subsequent calls to setTunnelNetworkSettings, the tunnel is stopped via the userInitiated stop reason within around 1 second from the first failure. This happens after a number of successful calls to setTunnelNetworkSettings have been made in the lifetime of a given packet tunnel process. We can confirm that no user ever initiates the disconnection. We can confirm that the only significant changes between the different calls to setTunnelNetworkSettings are that the parameters contain different private IPs for the tunnel settings - the routes and DNS settings remain the same. In our limited testing, it seems that we can replicate the behavior we're observing by removing the VPN profile while the tunnel is up. However, we are certain the same behavior happens under other circumstances without any user interaction. Is this what memory starvation looks like? Or is this something else? Our main concern is that the tunnel is killed and it is not brought back up even though our profile is set to be on-demand. It's difficult to give any promises about leaks to our users if the tunnel can be killed at any point and not be brought back. The spurious disconnections are a security issue for our app, we'd like to know if there's anything we can do differently so that this does not happen. We tried to get DTS, but given that we have no way to reproduce this issue with a minimal project. But we can reproduce the behavior (kill the tunnel by removing it's profile) from a minimal Xcode project, is that considered good enough for a reproduction?
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155
Jan ’26
Wi-Fi connectivity Issue - Captive.apple.com returns “application/octet-stream” instead of “text/html”,
In our system, when a user enables a mobile hotspot and the system connects to it, the system attempts to verify WIFI availability by sending an HTTP GET request to http://captive.apple.com. Normally, the server returns: HTTP Status: 200 (OK) Content-Type: text/html This has always been used as a sign of normal connectivity. Issue: Since last Friday, the server sometimes responds with: Content-Type: application/octet-stream When this occurs, our system determines that the network is unavailable and displays a connection warning (a “!” icon). Question: Has Apple recently made any backend or CDN configuration changes to captive.apple.com that could affect the response type? Any advice how can we solve this problem? Thanks!
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1k
Jan ’26
Disable HTTP/3 QUIC Forcibly with URLSession
Is there any way to forcibly disable using QUIC? I've noticed this ends up causing issues with our ISP / router, and noticed for many of our customers as well. Creating an ephemeral session doesn't change things, and setting the request to "assumeHttp3Capable" to false doesn't fix things either. We are using Cloudflare Workers as the URL we are hitting, and thus aren't able to disable this server-side.
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1.1k
Jan ’26
WiFi Aware connection cannot be established when both peers publish and subscribe
It works when one device is only a publisher and the other is only a subscriber. However, when both devices act as both publisher and subscriber simultaneously—which Apple’s documentation (https://developer.apple.com/documentation/wifiaware/adopting-wi-fi-aware#Declare-services) indicates is valid—the connection never establishes. After timing out, both NetworkListener and NetworkBrowser transition to the failed state. This appears to be a race condition in Network framework. Task.detached { try await NetworkListener( for: .wifiAware( .connecting( to: .myService, from: .allPairedDevices, datapath: .defaults ) ), using: .parameters { Coder( sending: ..., receiving: ..., using: NetworkJSONCoder() ) { TCP() } } ).run { connection in await self.add(connection: connection) } } Task.detached { try await NetworkBrowser( for: .wifiAware( .connecting( to: .allPairedDevices, from: .myService ) ), using: .tcp ).run { endpoints in for endpoint in endpoints { await self.connect(to: endpoint) } } }
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117
Jan ’26
Once started, NWPathMonitor appears to be kept alive until cancelled, but is this documented?
NWPathMonitor appears to retain itself (or is retained by some internal infrastructure) once it has been started until cancelled. This seems like it can lead to memory leaks if the references to to the monitor are dropped. Is this behavior documented anywhere? func nwpm_self_retain() { weak var weakRef: NWPathMonitor? autoreleasepool { let monitor: NWPathMonitor = NWPathMonitor() weakRef = monitor monitor.start(queue: .main) // monitor.cancel() // assertion fails unless this is called } assert(weakRef == nil) } nwpm_self_retain()
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136
Jan ’26
Why is localEndpoint not available for NEAppProxyTCPFlow?
NEAppProxyUDPFlow contains below property: open var localEndpoint: NWEndpoint? { get } Why is localEndpoint not available for NEAppProxyTCPFlow? Is there a way to determine the source port of a flow of type NEAppProxyTCPFlow within the following method of NETransparentProxyProvider? override func handleNewFlow(_ flow: NEAppProxyFlow) -> Bool {
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246
Jan ’26
Installing our app interferes with network connection in another app
Apologies if this is not the correct topic to post under. EpochField 5.2 is our application. It's a .NET MAUI application built against XCode 16. A customer of ours uses another app, TN3270, to connect to a mainframe host. After installing our app on an iPad and restarting the device, the TN3270 app will disconnect when suspended. Uninstalling our app (EpochField) will allow the TN3270 to suspend without disconnecting. We have tried removing background services, setting UIRequiresFullScreen to false or removing it entirely, and several other ideas. The only remedy seems to be uninstalling EpochField. On an iPad device: Install MochaSoft’s TN3270 app (free version is fine). Create a connection to ssl3270.nccourts.org, port 2023, SSL/TLS turned on, keep alive turned on. Verify that you can connect. Suspend the app by swiping up or choosing another app. Go back to TN3270 and verify that the app has not disconnected. Install EpochField 5.2. Do not run or configure the app, just install it. Repeat step 2. Restart the device. Open EpochField 5.2. You do not need to configure the app or login. Sometimes it isn't necessary to ever open EpochField to get the disconnects, but this is the most reliable way to reproduce the situation. Repeat step 2. The TN3270 app will now disconnect when suspended, even if EpochField is closed. You may need to wait a few seconds after suspending. Uninstall EpochField 5.2. Repeat step 2: the TN3270 app will now remain connected when suspended.
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228
Dec ’25
MultiPeer Connectivity: Device discovery succeeds but handshake fails when off-network
Hi, I am building an app that depends on multiple iOS devices connecting to a designated "coordinator" iOS device. I am using MPC, and it works great when the devices are connected to the same WiFi AP, with virtually 100% connection success. My definition of success is a near instant detection of available devices, >95% connection success rate, and a stable ongoing connection with no unexpected disconnects. The issue arises when the devices are not connected to the same WiFi network (or connected to no network with WiFi and bluetooth still on). Devices detect each other immediately, but when initiating a connection, both devices initiate a handshake, but the connection is not successful. In the few times where the connection succeeds, the connection quality is high, stable, and doesn't drop. Is this a known limitation of the framework? Could I be doing something wrong in my implementation?
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215
Dec ’25
Thread Network API not working
I'm trying to use ThreadNetwork API to manage TheradNetworks on device (following this documentation: https://developer.apple.com/documentation/threadnetwork/), but while some functions on THClient work (such as getPreferedNetwork), most don't (storeCredentials, retrieveAllCredentials). When calling these functions I get the following warning/error: Client: -[THClient getConnectionEntitlementValidity]_block_invoke - Error: -[THClient storeCredentialsForBorderAgent:activeOperationalDataSet:completion:]_block_invoke:701: - Error: Error Domain=NSCocoaErrorDomain Code=4099 "The connection to service with pid 414 named com.apple.ThreadNetwork.xpc was invalidated from this process." UserInfo={NSDebugDescription=The connection to service with pid 414 named com.apple.ThreadNetwork.xpc was invalidated from this process.} Error Domain=NSCocoaErrorDomain Code=4099 "The connection to service with pid 414 named com.apple.ThreadNetwork.xpc was invalidated from this process." UserInfo={NSDebugDescription=The connection to service with pid 414 named com.apple.ThreadNetwork.xpc was invalidated from this process.} Failed to store Thread credentials: Couldn’t communicate with a helper application. STEPS TO REPRODUCE Create new project Add Thread Network capability via Xcode UI (com.apple.developer.networking.manage-thread-network-credentials) Trigger storeCredentials let extendedMacData = "9483C451DC3E".hexadecimal let tlvHex = "0e080000000000010000000300001035060004001fffe002083c66f0dc9ef53f1c0708fdb360c72874da9905104094dce45388fd3d3426e992cbf0697b030d474c2d5332302d6e65773030310102250b04106c9f919a4da9b213764fc83f849381080c0402a0f7f8".hexadecimal // Initialize the THClient let thClient = THClient() // Store the credentials await thClient.storeCredentials(forBorderAgent: extendedMacData!, activeOperationalDataSet: tlvHex!) { error in if let error = error { print(error) print("Failed to store Thread credentials: \(error.localizedDescription)") } else { print("Successfully stored Thread credentials") } } NOTES: I tried with first calling getPreferedNetwork to initiate network permission dialog Tried adding meshcop to bojur services Tried with different release and debug build configurations
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529
Dec ’25
WiFi aware demo paring issue
I am developing a program on my chip and attempting to establish a connection with the WiFi Aware demo app launched by iOS 26. Currently, I am encountering an issue during the pairing phase. If I am the subscriber of the service and successfully complete the follow-up frame exchange of pairing bootstrapping, I see the PIN code displayed by iOS. Question 1: How should I use this PIN code? Question 2: Subsequently, I need to negotiate keys with iOS through PASN. What should I use as the password for the PASN SAE process? If I am the subscriber of the service and successfully complete the follow-up frame exchange of pairing bootstrapping, I should display the PIN code. Question 3: How do I generate this PIN code? Question 4: Subsequently, I need to negotiate keys with iOS through PASN. What should I use as the password for the PASN SAE process?
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228
Dec ’25
use `NEHotspotConfigurationManager.shared.apply(hotspotConfig)` to join a wifi slow on iphone17+
we use the api as NEHotspotConfigurationManager.shared.apply(hotspotConfig) to join a wifi, but we find that in in iphone 17+, some user report the time to join wifi is very slow the full code as let hotspotConfig = NEHotspotConfiguration(ssid: sSSID, passphrase: sPassword, isWEP: false) hotspotConfig.joinOnce = bJoinOnce if #available(iOS 13.0, *) { hotspotConfig.hidden = true } NEHotspotConfigurationManager.shared.apply(hotspotConfig) { [weak self] (error) in guard let self else { return } if let error = error { log.i("connectSSID Error while configuring WiFi: \(error.localizedDescription)") if error.localizedDescription.contains("already associated") { log.i("connectSSID Already connected to this WiFi.") result(["status": 0]) } else { result(["status": 0]) } } else { log.i("connectSSID Successfully connected to WiFi network \(sSSID)") result(["status": 1]) } } Normally it might only take 5-10 seconds, but on the iPhone 17+ it might take 20-30 seconds.
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298
Dec ’25
A Peek Behind the NECP Curtain
From time to time the subject of NECP grows up, both here on DevForums and in DTS cases. I’ve posted about this before but I wanted to collect those tidbits into single coherent post. 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" A Peek Behind the NECP Curtain NECP stands for Network Extension Control Protocol. It’s a subsystem within the Apple networking stack that controls which programs have access to which network interfaces. It’s vitally important to the Network Extension subsystem, hence the name, but it’s used in many different places. Indeed, a very familiar example of its use is the Settings > Mobile Data [1] user interface on iOS. NECP has no explicit API, although there are APIs that are offer some insight into its state. Continuing the Settings > Mobile Data example above, there is a little-known API, CTCellularData in the Core Telephony framework, that returns whether your app has access to WWAN. Despite having no API, NECP is still relevant to developers. The Settings > Mobile Data example is one place where it affects app developers but it’s most important for Network Extension (NE) developers. A key use case for NECP is to prevent VPN loops. When starting an NE provider, the system configures the NECP policy for the NE provider’s process to prevent it from using a VPN interface. This means that you can safely open a network connection inside your VPN provider without having to worry about its traffic being accidentally routed back to you. This is why, for example, an NE packet tunnel provider can use any networking API it wants, including BSD Sockets, to run its connection without fear of creating a VPN loop [1]. One place that NECP shows up regularly is the system log. Next time you see a system log entry like this: type: debug time: 15:02:54.817903+0000 process: Mail subsystem: com.apple.network category: connection message: nw_protocol_socket_set_necp_attributes [C723.1.1:1] setsockopt 39 SO_NECP_ATTRIBUTES … you’ll at least know what the necp means (-: Finally, a lot of NECP infrastructure is in the Darwin open source. As with all things in Darwin, it’s fine to poke around and see how your favourite feature works, but do not incorporate any information you find into your product. Stuff you uncover by looking in Darwin is not considered API. [1] Settings > Cellular Data if you speak American (-: [2] Network Extension providers can call the createTCPConnection(to:enableTLS:tlsParameters:delegate:) method to create an NWTCPConnection [3] that doesn’t run through the tunnel. You can use that if it’s convenient but you don’t need to use it. [3] NWTCPConnection is now deprecated, but there are non-deprecated equivalents. For the full story, see NWEndpoint History and Advice. Revision History 2025-12-12 Replaced “macOS networking stack” with “Apple networking stack” to avoid giving the impression that this is all about macOS. Added a link to NWEndpoint History and Advice. Made other minor editorial changes. 2023-02-27 First posted.
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2.5k
Dec ’25
Thoughts while looking into upgrading from SCNetworkReachabilityGetFlags to NWPathMonitor
I have been using the SCNetworkReachabilityGetFlags for 10+ years to inform users that their request won't work. In my experience this works pretty well although i am aware of the limitations. Now, i am looking into the NWPathMonitor, and i have one situation that i'm trying to. get my head around - it's asynchronous. Specifically, i am wondering what to do when my geofences trigger and i want to check network connectivity - i want to tell the user why the operation i'll perform because of the trigger couldn't be done. SO. say i start a NWPathMonitor in didFinishLaunchingWithOptions. When the app is booted up because of a geofence trigger, might i not end up in a case where my didEnterRegion / didExitRegion gets called before the NWPathMonitor has gotten its first status? The advantage here with SCNetworkReachabilityGetFlags, as i understand it, would be that it's synchronous? If i want to upgrade to nwpathmonitor, i guess i have to do a method that creates a nwpathmonitor, uses a semaphore to wait for the first callback, then contunues? Thoughts appreciated
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560
Dec ’25
How to set the custom DNS with the Network client
We are facing a DNS resolution issue with a specific ISP, where our domain name does not resolve correctly using the system DNS. However, the same domain works as expected when a custom DNS resolver is used. On Android, this is straightforward to handle by configuring a custom DNS implementation using OkHttp / Retrofit. I am trying to implement a functionally equivalent solution in native iOS (Swift / SwiftUI). **Android Reference (Working Behavior) : ** val dns = DnsOverHttps.Builder() .client(OkHttpClient()) .url("https://cloudflare-dns.com/dns-query".toHttpUrl()) .bootstrapDnsHosts(InetAddress.getByName("1.1.1.1")).build() OkHttpClient.Builder().dns(dns).build() **Attempted iOS Approach ** I attempted the following approach : Resolve the domain to an IP address programmatically (using DNS over HTTPS) Connect directly to the resolved IP address Set the original domain in the Host HTTP header **DNS Resolution via DoH : ** func resolveDomain(domain: String) async throws -> String { guard let url = URL( string: "https://cloudflare-dns.com/dns-query?name=\(domain)&type=A" ) else { throw URLError(.badURL) } var request = URLRequest(url: url) request.setValue("application/dns-json", forHTTPHeaderField: "accept") let (data, _) = try await URLSession.shared.data(for: request) let response = try JSONDecoder().decode(DNSResponse.self, from: data) guard let ip = response.Answer?.first?.data else { throw URLError(.cannotFindHost) } return ip } **API Call Using Resolved IP : ** func callAPIUsingCustomDNS() async throws { let ip = try await resolveDomain(domain: "example.com") guard let url = URL(string: "https://\(ip)") else { throw URLError(.badURL) } let configuration = URLSessionConfiguration.ephemeral let session = URLSession( configuration: configuration, delegate: CustomURLSessionDelegate(originalHost: "example.com"), delegateQueue: .main ) var request = URLRequest(url: url) request.setValue("example.com", forHTTPHeaderField: "Host") let (_, response) = try await session.data(for: request) print("Success: \(response)") } **Problem Encountered ** When connecting via the IP address, the TLS handshake fails with the following error: Error Domain=NSURLErrorDomain Code=-1200 "A TLS error caused the secure connection to fail." This appears to happen because iOS sends the IP address as the Server Name Indication (SNI) during the TLS handshake, while the server’s certificate is issued for the domain name. **Custom URLSessionDelegate Attempt : ** class CustomURLSessionDelegate: NSObject, URLSessionDelegate { let originalHost: String init(originalHost: String) { self.originalHost = originalHost } func urlSession( _ session: URLSession, didReceive challenge: URLAuthenticationChallenge, completionHandler: @escaping (URLSession.AuthChallengeDisposition, URLCredential?) -> Void ) { guard challenge.protectionSpace.authenticationMethod == NSURLAuthenticationMethodServerTrust, let serverTrust = challenge.protectionSpace.serverTrust else { completionHandler(.performDefaultHandling, nil) return } let sslPolicy = SecPolicyCreateSSL(true, originalHost as CFString) let basicPolicy = SecPolicyCreateBasicX509() SecTrustSetPolicies(serverTrust, [sslPolicy, basicPolicy] as CFArray) var error: CFError? if SecTrustEvaluateWithError(serverTrust, &error) { completionHandler(.useCredential, URLCredential(trust: serverTrust)) } else { completionHandler(.cancelAuthenticationChallenge, nil) } } } However, TLS validation still fails because the SNI remains the IP address, not the domain. I would appreciate guidance on the supported and App Store–compliant way to handle ISP-specific DNS resolution issues on iOS. If custom DNS or SNI configuration is not supported, what alternative architectural approaches are recommended by Apple?
1
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290
Dec ’25
How to close / cancel a NetworkConnection
Hello, I have an app that was using the iOS 18 Network Framework APIs. It used Peer to Peer, QUIC and Bonjour. It was all working as expected. I wanted to upgrade to the new iOS 26 Network Framework APIs (NetworkBrowser, NetworkListener, NetworkConnection...). I have things working (multiple devices can discover each other, connection to each other and send messages to each other) but my app crashes when I go to toggle of all the networking stuff. In the iOS 18 Network Framework API NWConnection had a .cancel() function I could use to tell the other side the connection was done. I dont see a cancel function for NetworkConnection. My question is - how do I properly close down a NetworkConnection and also properly tell the other side the connection is done.
2
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186
Dec ’25
Wi-Fi Raw Socket Disconnection Issue on iPhone 17 Series
On my iPhone 16 Pro and iPhone 16 Pro Max devices, running iOS 26.0, 26.0.1, and 26.1, Wi-Fi raw socket communication works flawlessly. Even after keeping the connection active for over 40 minutes, there are no disconnections during data transmission. However, on the iPhone 17 and iPhone 17 Pro, the raw socket connection drops within 20 seconds. Once it disconnects, the socket cannot reconnect unless the Wi-Fi module itself is reset. I believe this issue is caused by a bug in the iPhone 17 series’ communication module. I have looked into many cases, and it appears to be related to a bug in the N1 chipset. Are there any possible solutions or workarounds for this issue?
6
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317
Dec ’25