We have a setup where the system uses proxy settings configured via a PAC file. We are investigating how NWConnection behaves inside a Network Extension (NETransparentProxyProvider) with a transparent proxy configuration based on this PAC file.
Scenario:
The browser makes a connection which the PAC file resolves as "DIRECT" (bypassing the proxy)
Our Network Extension intercepts this traffic for analysis
The extension creates a new connection using NWConnection to the original remote address.
The issue: despite the PAC file’s "DIRECT" decision, NWConnection still respects the system proxy settings and routes the connection through the proxy.
Our questions:
Is it correct that NWConnection always uses the system proxy if configured ?
Does setting preferNoProxies = true guarantee bypassing the system proxy?
Additionally:
Whitelisting IPs in the Network Extension to avoid interception is not a viable solution because IPs may correspond to multiple services, and the extension only sees IP addresses, not domains (e.g., we want to skip scanning meet.google.com traffic but still scan other Google services on the same IP range).
Are there any recommended approaches or best practices to ensure that connections initiated from a Network Extension can truly bypass the proxy (for example, for specific IP ranges or domains)?
CFNetwork
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Hi,
I’m trying to download a remote file in the background, but I keep getting a strange behaviour where URLSession download my file indefinitely during a few minutes, without calling urlSession(_:downloadTask:didFinishDownloadingTo:) until the download eventually times out.
To find out that it’s looping, I’ve observed the total bytes written on disk by implementing urlSession(_:downloadTask:didWriteData:totalBytesWritten:totalBytesExpectedToWrite:).
Note that I can't know the size of the file. The server is not able to calculate the size.
Below is my implementation.
I create an instance of URLSession like this:
private lazy var session: URLSession = {
let configuration = URLSessionConfiguration.background(withIdentifier: backgroundIdentifier)
configuration.isDiscretionary = false
configuration.sessionSendsLaunchEvents = true
return URLSession(configuration: configuration,
delegate: self,
delegateQueue: nil)
}()
My service is using async/await so I have implemented an AsyncThrowingStream :
private var downloadTask: URLSessionDownloadTask?
private var continuation: AsyncThrowingStream<(URL, URLResponse), Error>.Continuation?
private var stream: AsyncThrowingStream<(URL, URLResponse), Error> {
AsyncThrowingStream<(URL, URLResponse), Error> { continuation in
self.continuation = continuation
self.continuation?.onTermination = { @Sendable [weak self] data in
self?.downloadTask?.cancel()
}
downloadTask?.resume()
}
}
Then to start the download, I do :
private func download(with request: URLRequest) async throws -> (URL, URLResponse) {
do {
downloadTask = session.downloadTask(with: request)
for try await (url, response) in stream {
return (url, response)
}
throw NetworkingError.couldNotBuildRequest
} catch {
throw error
}
}
Then in the delegate :
public func urlSession(_ session: URLSession,
downloadTask: URLSessionDownloadTask,
didFinishDownloadingTo location: URL) {
guard let response = downloadTask.response,
downloadTask.error == nil,
(response as? HTTPURLResponse)?.statusCode == 200 else {
continuation?.finish(throwing: downloadTask.error)
return
}
do {
let documentsURL = try FileManager.default.url(for: .documentDirectory,
in: .userDomainMask,
appropriateFor: nil,
create: false)
let savedURL = documentsURL.appendingPathComponent(location.lastPathComponent)
try FileManager.default.moveItem(at: location, to: savedURL)
continuation?.yield((savedURL, response))
continuation?.finish()
} catch {
continuation?.finish(throwing: error)
}
}
I also tried to replace let configuration = URLSessionConfiguration.background(withIdentifier: backgroundIdentifier) by let configuration = URLSessionConfiguration.default and this time I get a different error at the end of the download:
Task <0457F755-9C52-4CFB-BDB2-F378D0C94912>.<1> failed strict content length check - expected: 0, received: 530692, received (uncompressed): 0
Task <0457F755-9C52-4CFB-BDB2-F378D0C94912>.<1> finished with error [-1005] Error Domain=NSURLErrorDomain Code=-1005 "The network connection was lost." UserInfo={NSLocalizedDescription=The network connection was lost., NSErrorFailingURLStringKey=https:/<host>:8190/proxy?Func=downloadVideoByUrl&SessionId=slufzwrMadvyJad8Lkmi9RUNAeqeq, NSErrorFailingURLKey=https://<host>:8190/proxy?Func=downloadVideoByUrl&SessionId=slufzwrMadvyJad8Lkmi9RUNAeqeq, _NSURLErrorRelatedURLSessionTaskErrorKey=(
"LocalDownloadTask <0457F755-9C52-4CFB-BDB2-F378D0C94912>.<1>"
), _NSURLErrorFailingURLSessionTaskErrorKey=LocalDownloadTask <0457F755-9C52-4CFB-BDB2-F378D0C94912>.<1>, NSUnderlyingError=0x300d9a7c0 {Error Domain=kCFErrorDomainCFNetwork Code=-1005 "(null)" UserInfo={NSErrorPeerAddressKey=<CFData 0x302139db0 [0x1fcb1f598]>{length = 16, capacity = 16, bytes = 0x10021ffe91e227500000000000000000}}}}
The log "failed strict content length check” made me look into the response header, which has the following:
content-length: 0
Content-Type: application/force-download
Transfer-encoding: chunked
Connection: KEEP-ALIVE
Content-Transfer-Encoding: binary
So it should be fine the way I setup my URLSession.
The download works fine in Chrome/Safari/Chrome or Postman.
My code used to work a couple of weeks before, so I expect something has changed on the server side, but I can’t find what, and I don’t get much help from the guys on the server side.
Has anyone an idea of what’s going on?
Topic:
App & System Services
SubTopic:
Networking
Tags:
Network
Background Tasks
CFNetwork
Foundation
I'm struggling to understand why the async-await version of URLSession download task APIs do not call the delegate functions, whereas the old non-async version that returns a reference to the download task works just fine.
Here is my sample code:
class DownloadDelegate: NSObject, URLSessionDownloadDelegate {
func urlSession(_ session: URLSession,
downloadTask: URLSessionDownloadTask,
didWriteData bytesWritten: Int64,
totalBytesWritten: Int64,
totalBytesExpectedToWrite: Int64) {
// This only prints the percentage of the download progress.
let calculatedProgress = Float(totalBytesWritten) / Float(totalBytesExpectedToWrite)
let formatter = NumberFormatter()
formatter.numberStyle = .percent
print(formatter.string(from: NSNumber(value: calculatedProgress))!)
}
}
// Here's the VC.
final class DownloadsViewController: UIViewController {
private let url = URL(string: "https://pixabay.com/get/g0b9fa2936ff6a5078ea607398665e8151fc0c10df7db5c093e543314b883755ecd43eda2b7b5178a7e613a35541be6486885fb4a55d0777ba949aedccc807d8c_1280.jpg")!
private let delegate = DownloadDelegate()
private lazy var session = URLSession(configuration: .default, delegate: delegate, delegateQueue: nil)
// for the async-await version
private var task: Task<Void, Never>?
// for the old version
private var downloadTask: URLSessionDownloadTask?
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(animated)
task?.cancel()
task = nil
task = Task {
let (_, _) = try! await session.download(for: URLRequest(url: url))
self.task = nil
}
// If I uncomment this, the progress listener delegate function above is called.
// downloadTask?.cancel()
// downloadTask = nil
// downloadTask = session.downloadTask(with: URLRequest(url: url))
// downloadTask?.resume()
}
}
What am I missing here?
Hi everyone,
I'm developing a visionOS app that allows users to download large video files (similar to a movie download experience, with each file being around 10 GB). I've successfully implemented the core video download functionality using URLSession, and everything works as expected while the app is active.
Now, I’m looking to support background downloading. Specifically, I want users to be able to start a download and then leave the app (e.g., switch apps or return to the home screen) while the download continues in the background.
Additionally, I’d like to confirm a specific scenario:
If the user starts a download, then removes the headset (keeping the device turned on and connected to power), will the download continue in the background? Or does visionOS suspend the app or downloads in this case?
I’m considering using a background URLSessionConfiguration (as done in iOS/macOS) to enable this behavior, but I’m not sure if it behaves the same way on visionOS or if there are special limitations or best practices when handling large downloads on this platform.
Any insights or official guidance would be greatly appreciated!
Thanks!
I am using a URLSessionWebSocketTask. When trying to receive messages while the app is backgrounded, the receive() method fails with an NSError where the domain is NSPOSIXErrorDomain and the code is ECONNABORTED. That behavior is good. However, when this happens, the URLSessionWebSocketTask reports a closeCode of invalid, which is supposed to denote that the connection is still open. However, the connection state property is reporting completed. I feel that the closeCode property should be reporting something like abnormalClosure in this case. Either way, this seems like a bug or the documentation is incorrect.
I'm establishing a connection with NWListener and NWConnection which is working great. However, if the listener disappears, a lot of logs are appearing:
Is there a way to hide these logs?
I'm aware of OS_ACTIVITY_MODE=disabled, but that will also hide a lot of other logs.
I also know you can hide these using Xcode's filtering. I'm looking for a programmatically way to hide these completely. I'm not interested in seeing these at all, or, at least, I want to be in control.
Thanks!
When i try to set the value ‘false’ for ‘usesClassicLoadingMode’ it is getting crashed.
The crash logs has been shared below
Ex:
let config = URLSessionConfiguration.default
if #available(iOS 18.4, *) {
config.usesClassicLoadingMode = false
}
Error log :
*** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '-[__NSCFBoolean objectForKeyedSubscript:]: unrecognized selector sent to instance 0x1f655c390'
*** First throw call stack:
(0x188ae52ec 0x185f69a7c 0x188b4f67c 0x1889fcb84 0x1889fc4f0 0x191393bc8 0x1889ec8a0 0x1889ec6e4 0x191393ad0 0x191344dac 0x191344b58 0x107cfa064 0x107ce36d0 0x191343fcc 0x1891b3b18 0x1892dae58 0x189235c60 0x18921e270 0x18921d77c 0x18921a8ac 0x107ce0584 0x107cfa064 0x107ce891c 0x107ce95d8 0x107ceabcc 0x107cf5894 0x107cf4eb0 0x212f51660 0x212f4e9f8)
terminating due to uncaught exception of type NSException
Can you please provider the resolution steps
Hello,
I'm experiencing an issue where WKWebView consistently fails to load a specific URL on the iOS 18.4 simulator (Xcode 16.3). The error is as follows:
Error Domain=NSURLErrorDomain Code=-1005 "The network connection was lost."
UserInfo={
_kCFStreamErrorCodeKey=-4,
_kCFStreamErrorDomainKey=4,
NSUnderlyingError=Error Domain=kCFErrorDomainCFNetwork Code=-1005,
NSErrorFailingURLKey=[REDACTED]
}
Key Observations:
This URL fails consistently only on the iOS 18.4 simulator.
The same URL loads without issue in iOS 18.3 and 18.2 simulators.
The backend is serving a valid HTTPS certificate chain, and the server appears to be presenting it properly.
The same application appears to work on a real iPhone running 18.4.
Certificate Chain for the Failing URL
Leaf: WR3 (Valid: Mar 17, 2025 – Jun 15, 2025)
Intermediate 1: GTS Root R1 (Valid: Dec 13, 2023 – Feb 20, 2029)
Intermediate 2: GlobalSign Root CA (Valid: Jun 19, 2020 – Jan 28, 2028)
Other URLs Work Fine in iOS 18.4 Simulator
WKWebView successfully loads the following URLs with similar or more complex certificate chains:
https://google.com → WR2, GTS Root R1, GlobalSign Root CA
https://amazon.com → DigiCert Global CA G2, DigiCert Global Root G2, VeriSign G5
https://stackoverflow.com → E5, ISRG Root X1
https://shopify.com → GlobalSign Root CA, GTS Root R4, WE1
This suggests the issue may not be with general network or certificate trust but instead something specific about how iOS 18.4 handles this domain or certificate configuration in the simulator.
Any insights on how to solve this would be greatly appreciated.
When I try to implement the new Background Task options in the same way as they show in the WWDC video (on watchOS) likes this:
let config = URLSessionConfiguration.background(withIdentifier: "SESSION_ID")
config.sessionSendsLaunchEvents = true
let session = URLSession(configuration: config)
let response = await withTaskCancellationHandler {
try? await session.data(for: request)
} onCancel: {
let task = session.downloadTask(with: request))
task.resume()
}
I'm receiving the following error:
Terminating app due to uncaught exception 'NSGenericException', reason: 'Completion handler blocks are not supported in background sessions. Use a delegate instead.'
Did I forget something?
I am trying to convert a simple URLSession request in Swift to using NWConnection. This is because I want to make the request using a Proxy that requires Authentication. I posted this SO Question about using a proxy with URLSession. Unfortunately no one answered it but I found a fix by using NWConnection instead.
Working Request
func updateOrderStatus(completion: @escaping (Bool) -> Void) {
let orderLink = "https://shop.ccs.com/51913883831/orders/f3ef2745f2b06c6b410e2aa8a6135847"
guard let url = URL(string: orderLink) else {
completion(true)
return
}
let cookieStorage = HTTPCookieStorage.shared
let config = URLSessionConfiguration.default
config.httpCookieStorage = cookieStorage
config.httpCookieAcceptPolicy = .always
let session = URLSession(configuration: config)
var request = URLRequest(url: url)
request.httpMethod = "GET"
request.setValue("text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8", forHTTPHeaderField: "Accept")
request.setValue("none", forHTTPHeaderField: "Sec-Fetch-Site")
request.setValue("navigate", forHTTPHeaderField: "Sec-Fetch-Mode")
request.setValue("Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/18.0.1 Safari/605.1.15", forHTTPHeaderField: "User-Agent")
request.setValue("en-US,en;q=0.9", forHTTPHeaderField: "Accept-Language")
request.setValue("gzip, deflate, br", forHTTPHeaderField: "Accept-Encoding")
request.setValue("document", forHTTPHeaderField: "Sec-Fetch-Dest")
request.setValue("u=0, i", forHTTPHeaderField: "Priority")
// make the request
}
Attempted Conversion
func updateOrderStatusProxy(completion: @escaping (Bool) -> Void) {
let orderLink = "https://shop.ccs.com/51913883831/orders/f3ef2745f2b06c6b410e2aa8a6135847"
guard let url = URL(string: orderLink) else {
completion(true)
return
}
let proxy = "resi.wealthproxies.com:8000:akzaidan:x0if46jo-country-US-session-7cz6bpzy-duration-60"
let proxyDetails = proxy.split(separator: ":").map(String.init)
guard proxyDetails.count == 4, let port = UInt16(proxyDetails[1]) else {
print("Invalid proxy format")
completion(false)
return
}
let proxyEndpoint = NWEndpoint.hostPort(host: .init(proxyDetails[0]),
port: NWEndpoint.Port(integerLiteral: port))
let proxyConfig = ProxyConfiguration(httpCONNECTProxy: proxyEndpoint, tlsOptions: nil)
proxyConfig.applyCredential(username: proxyDetails[2], password: proxyDetails[3])
let parameters = NWParameters.tcp
let privacyContext = NWParameters.PrivacyContext(description: "ProxyConfig")
privacyContext.proxyConfigurations = [proxyConfig]
parameters.setPrivacyContext(privacyContext)
let host = url.host ?? ""
let path = url.path.isEmpty ? "/" : url.path
let query = url.query ?? ""
let fullPath = query.isEmpty ? path : "\(path)?\(query)"
let connection = NWConnection(
to: .hostPort(
host: .init(host),
port: .init(integerLiteral: UInt16(url.port ?? 80))
),
using: parameters
)
connection.stateUpdateHandler = { state in
switch state {
case .ready:
print("Connected to proxy: \(proxyDetails[0])")
let httpRequest = """
GET \(fullPath) HTTP/1.1\r
Host: \(host)\r
Connection: close\r
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8\r
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/18.0.1 Safari/605.1.15\r
Accept-Language: en-US,en;q=0.9\r
Accept-Encoding: gzip, deflate, br\r
Sec-Fetch-Dest: document\r
Sec-Fetch-Mode: navigate\r
Sec-Fetch-Site: none\r
Priority: u=0, i\r
\r
"""
connection.send(content: httpRequest.data(using: .utf8), completion: .contentProcessed({ error in
if let error = error {
print("Failed to send request: \(error)")
completion(false)
return
}
// Read data until the connection is complete
self.readAllData(connection: connection) { finalData, readError in
if let readError = readError {
print("Failed to receive response: \(readError)")
completion(false)
return
}
guard let data = finalData else {
print("No data received or unable to read data.")
completion(false)
return
}
if let body = String(data: data, encoding: .utf8) {
print("Received \(data.count) bytes")
print("\n\nBody is \(body)")
completion(true)
} else {
print("Unable to decode response body.")
completion(false)
}
}
}))
case .failed(let error):
print("Connection failed for proxy \(proxyDetails[0]): \(error)")
completion(false)
case .cancelled:
print("Connection cancelled for proxy \(proxyDetails[0])")
completion(false)
case .waiting(let error):
print("Connection waiting for proxy \(proxyDetails[0]): \(error)")
completion(false)
default:
break
}
}
connection.start(queue: .global())
}
private func readAllData(connection: NWConnection,
accumulatedData: Data = Data(),
completion: @escaping (Data?, Error?) -> Void) {
connection.receive(minimumIncompleteLength: 1, maximumLength: 65536) { data, context, isComplete, error in
if let error = error {
completion(nil, error)
return
}
// Append newly received data to what's been accumulated so far
let newAccumulatedData = accumulatedData + (data ?? Data())
if isComplete {
// If isComplete is true, the server closed the connection or ended the stream
completion(newAccumulatedData, nil)
} else {
// Still more data to read, so keep calling receive
self.readAllData(connection: connection,
accumulatedData: newAccumulatedData,
completion: completion)
}
}
}
When I make a local network HTTP request, an error occurs. I'm sure I've granted wireless data permissions and local network permissions, and I'm connected to the correct Wi-Fi. This problem is intermittent, but once it happens, it will keep happening, and the only way to fix it is to restart the phone. Here is the error log:
sessionTaskFailed(error: Error Domain=NSURLErrorDomain Code=-1009 "似乎已断开与互联网的连接。" UserInfo={_kCFStreamErrorCodeKey=50, NSUnderlyingError=0x30398a5b0 {Error Domain=kCFErrorDomainCFNetwork Code=-1009 "(null)" UserInfo={_NSURLErrorNWPathKey=unsatisfied (Local network prohibited), interface: en0[802.11], uses wifi, _kCFStreamErrorCodeKey=50, _kCFStreamErrorDomainKey=1}}, _NSURLErrorFailingURLSessionTaskErrorKey=LocalDataTask .<63>, _NSURLErrorRelatedURLSessionTaskErrorKey=(
"LocalDataTask .<63>"
), NSLocalizedDescription=似乎已断开与互联网的连接。, NSErrorFailingURLStringKey=http://192.168.2.1:80/v1/parameters, NSErrorFailingURLKey=http://192.168.2.1:80/v1/parameters, _kCFStreamErrorDomainKey=1})
Apology for repost. I needed to fix the tags for original thread.
https://developer.apple.com/forums/thread/777159
On iOS 18.3, I noted that partition "HTTPCookiePropertyKey: StoragePartition" is not observed to be set for cookies returned from the wkwebview cookie store.
Now on 18.4 beta 4 we are now seeing those same cookies are populated with a partition property. Is there documentation for this change? Is it intended to be suddenly populated in 18.4?
Now that partition property is set, HTTPCookieStorage.shared.cookies(for: serverUri) doesn't seem to return the expected cookies correctly. For context, we are using the cookies extracted from wkwebview, setting them in HTTPCookieStorage.shared and using URLSession to make network calls outside the webivew. Works fine once I forcefully set partition on the cookie to nil.
More details on what the cookie looks like here: https://feedbackassistant.apple.com/feedback/16906526
Hopefully this is on your radar?
On iOS 18.3, I noted that partition "HTTPCookiePropertyKey: StoragePartition" is not observed to be set for cookies returned from the wkwebview cookie store.
Now on 18.4 beta 4 we are now seeing those same cookies are populated with a partition property. Is there documentation for this change? Is it intended to be suddenly populated in 18.4?
Now that partition property is set, HTTPCookieStorage.shared.cookies(for: serverUri) doesn't seem to return the expected cookies correctly. For context, we are using the cookies extracted from wkwebview, setting them in HTTPCookieStorage.shared and using URLSession to make network calls outside the webivew. Works fine once I forcefully set partition on the cookie to nil.
More details on what the cookie looks like here:
https://feedbackassistant.apple.com/feedback/16906526
Hopefully this is on your radar?
When my app launches, it makes maybe 9 or so network requests to load initial data. It also reads some data from disc.
Sporadically, I'm seeing an issue where some of the network requests succeed, but anything involving reading from disc does not load immediately. I'm able to move around in the app, tap buttons, swap tabs, swipe pages, so my main actor isn't stuck. Other data that don't involve disc reading / writing is also blank. About 2 minutes in, suddenly everything loads (both stuff from disc and stuff from the network), nearly instantly, the way it should have done when the app launched.
Server logs show more initial network requests succeed than we can see data loaded in the app, and then about 2 minutes later, there's a flood of the rest of the requests which then succeed.
The responses to some of these initial network requests cause us to make other network requests, and the sever sees some of those start right away.
However, other consequences of these first requests are to touch the disc (to search for manually-cached data), and anything that is supposed to happen after that does not succeed until the 2 minute mark.
But what bothers me is some things in the app which don't touch the disc also seem to have successful network requests.
I'm seeing it on an iPhone 14Pro running iOS 18.2.1, with 607 GB of disc space available.
When I take screenshots of the loading screens in my app during the apparent freeze, the clock in the screenshots are right - they reflect the clock at the moment I took the screenshot, but the EXIF data in all dozen or so images shows the exact second 2 minutes later when the server gets the resulting flood of network requests. Screenshots taken after the freeze is over have exif timestamps that match the screenshots, as short as 5 seconds after the freeze ends. The screenshot file names, though sequential, are out of order. for instance, some screenshots from 12:58 have file names numbered after screenshots taken at 12:59. but not all are out of order.
This seems like disc contention has spread outside the app, and is impacting the system writing the images to disc.
How do I diagnose a cause for this? How does disc contention affect the networking? I have caching turned off for my network requests. We only have a manual image cache, but I don't know how that would stall the display of data that should fetch and display without attempting to hit the image cache.
This happens maybe a couple of times a day for some people, maybe once every couple of weeks for others, but of course, it never when we're trying to debug it.
My app sent a network request to the backend. The backend returns a 200, but the front end received a -1001 or -1005 NSURLError. Any clue why this could be happening?
I would like to develop a macOS app that would automatically switch Network Locations based on certain criteria. I want to publish this on the Mac App Store, but I'm unsure if this functionality is permitted.
I've searched through the App Store Review Guidelines and documentation on NetworkExtension and SystemConfiguration frameworks, but I haven't found clear information on whether:
Programmatically changing Network Locations is allowed in sandboxed App Store apps
What specific entitlements would be required
If there are any API-approved ways to do this without shell commands
I'd like to avoid investing significant development time if this type of functionality would ultimately be rejected. As a relatively new Apple platform developer, any guidance on:
The appropriate frameworks/APIs to use
Required entitlements
Whether this functionality is even permitted for App Store distribution
would be incredibly helpful.
Thank you in advance for any insights!
Topic:
App & System Services
SubTopic:
Networking
Tags:
Network Extension
System Configuration
CFNetwork
Hi,
I have a file provider based MacOS application where i have a drive added and am trying to download a folder from that drive.
The folder has sub folders and large files in it.
After some time of download started, i keep getting below error.
error: ["The operation could not be completed. Cannot allocate memory", [code: 12, domain: "NSPOSIXErrorDomain"]
The download action is triggered via Finder's download icon(cloud icon with down arrow).
I am using native URLSession to download the files from server. No third party library is used.
What could be the possible reasons for "can not allocate memory" issue?
CFNetwork None CFURLResponseGetRecommendedCachePolicy None 0
CFNetwork None CFHTTPCookieStorageUnscheduleFromRunLoop None 0
CFNetwork None /_/_CFNetworkAgentMessageProcessorMain None 0
CFNetwork None CFURLDownloadCancel None 0
CFNetwork None CFURLDownloadCancel None 0
libdispatch.dylib None /_dispatch/_block/_async/_invoke2 None
We've observed intermittent crashes in our production environment, exclusively affecting customers running macOS 10.15 and 11. The crash logs consistently show a stack trace involving CFHTTPCookieStorageUnscheduleFromRunLoop and CFURLDownloadCancel within the CFNetwork framework. This suggests potential issues with cookie storage management and/or URL download cancellation.
Could the team please analyze these crash logs and provide insights into:
The root cause of the crashes.
Potential race conditions or synchronization issues.
Recommendations for mitigating or resolving the problem.
Your assistance in resolving this issue is greatly appreciated."
We found there is a significant crash reports (most of them are from iOS 17, the rest are iOS 16 and 15) comes from network loader from CFNetwork. Apparently it seems there are two types of crashes if we checked from the stack trace, the one we found from both Xcode organizer and 3rd party crash reporter is referring to URLConnectionLoader::loadWithWhatToDo and the other one from our 3rd party crash reporter (didn’t found the report from Xcode organizer) referring to
_CFURLResponseCreateFromArchiveList (this one only happened on iOS 17.5 and later devices). It seems that they are both kinda similar which might point to the same root cause.
From what I’ve seen, we never touch the lower level API directly, we usually use the URLSession to manage our API request. The crashed stack trace also didn’t give any indication about which of our app code that triggered the crash, it only shows calls to Apple’s internal SDKs so we are unsure how to approach this issue meanwhile the crash event already reached 800+ in the last 30 days. Unfortunately, we cannot reproduce the issue as the stack trace itself seems unclear to us.
I have submitted a report through feedback assistant with number: FB14679252.
Would appreciate if anyone can give any advice on what we can do to avoid this in the future and probably any hint on why it could happened.
Hereby I attached the crash reports that we found each from Xcode crash report and our 3rd party crash reporter (the report said it crashed on com.apple.CFNetwork.LoaderQ) so you could get a glimpse of the similarity.
Xcode crash report
xcode crash report.crash
3rd party crash report
3rd party crash report.txt
I have currently created an app which contains an upload button which when clicked upload health data using HealthKit to an AWS S3 bucket.
Now I want to implement an automatic file upload mechanism which would mean that the app is installed and opened just once - and then the upload must happen on a schedule (once daily) from the background without ever having to open the app again.
I've tried frameworks like NSURLSession and BackgroundTasks but nothing seems to work. Is this use case even possible to implement? Does iOS allow this?
The file is just a few KBs in size.
For reference, here is the Background Tasks code:
import UIKit
import BackgroundTasks
import HealthKit
class AppDelegate: NSObject, UIApplicationDelegate {
let backgroundTaskIdentifier = "com.yourapp.healthdata.upload"
func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
// Register the background task
BGTaskScheduler.shared.register(forTaskWithIdentifier: backgroundTaskIdentifier, using: nil) { task in
self.handleHealthDataUpload(task: task as! BGAppRefreshTask)
}
// Schedule the first upload task
scheduleDailyUpload()
return true
}
// Schedule the background task for daily execution
func scheduleDailyUpload() {
print("[AppDelegate] Scheduling daily background task.")
let request = BGAppRefreshTaskRequest(identifier: backgroundTaskIdentifier)
request.earliestBeginDate = Date(timeIntervalSinceNow: 24*60*60)
do {
try BGTaskScheduler.shared.submit(request)
print("[AppDelegate] Daily background task scheduled.")
} catch {
print("[AppDelegate] Could not schedule daily background task: \(error.localizedDescription)")
}
}
// Handle the background task when it's triggered by the system
func handleHealthDataUpload(task: BGAppRefreshTask) {
print("[AppDelegate] Background task triggered.")
// Call your upload function with completion handler
HealthStoreManager.shared.fetchAndUploadHealthData { success in
if success {
print("[AppDelegate] Upload completed successfully.")
task.setTaskCompleted(success: true)
// Schedule the next day's upload after a successful upload
self.scheduleDailyUpload()
} else {
print("[AppDelegate] Upload failed.")
task.setTaskCompleted(success: false)
}
}
// Handle task expiration (e.g., if upload takes too long)
task.expirationHandler = {
print("[AppDelegate] Background task expired.")
task.setTaskCompleted(success: false)
}
}
}