General: Forums subtopic: App & System Services > Networking TN3151 Choosing the right networking API Networking Overview document — Despite the fact that this is in the archive, this is still really useful. TLS for App Developers forums post Choosing a Network Debugging Tool documentation WWDC 2019 Session 712 Advances in Networking, Part 1 — This explains the concept of constrained networking, which is Apple’s preferred solution to questions like How do I check whether I’m on Wi-Fi? TN3135 Low-level networking on watchOS TN3179 Understanding local network privacy Adapt to changing network conditions tech talk Understanding Also-Ran Connections forums post Extra-ordinary Networking forums post Foundation networking: Forums tags: Foundation, CFNetwork URL Loading System documentation — NSURLSession, or URLSession in Swift, is the recommended API for HTTP[S] on Apple platforms. Moving to Fewer, Larger Transfers forums post Testing Background Session Code forums post Network framework: Forums tag: Network Network framework documentation — Network framework is the recommended API for TCP, UDP, and QUIC on Apple platforms. Building a custom peer-to-peer protocol sample code (aka TicTacToe) Implementing netcat with Network Framework sample code (aka nwcat) Configuring a Wi-Fi accessory to join a network sample code Moving from Multipeer Connectivity to Network Framework forums post NWEndpoint History and Advice forums post Wi-Fi (general): How to modernize your captive network developer news post Wi-Fi Fundamentals forums post Filing a Wi-Fi Bug Report forums post Working with a Wi-Fi Accessory forums post — This is part of the Extra-ordinary Networking series. Wi-Fi (iOS): TN3111 iOS Wi-Fi API overview technote Wi-Fi Aware framework documentation WirelessInsights framework documentation iOS Network Signal Strength forums post Network Extension Resources Wi-Fi on macOS: Forums tag: Core WLAN Core WLAN framework documentation Secure networking: Forums tags: Security Apple Platform Security support document Preventing Insecure Network Connections documentation — This is all about App Transport Security (ATS). WWDC 2017 Session 701 Your Apps and Evolving Network Security Standards [1] — This is generally interesting, but the section starting at 17:40 is, AFAIK, the best information from Apple about how certificate revocation works on modern systems. WWDC 2025 Session 314 Get ahead with quantum-secure cryptography Available trusted root certificates for Apple operating systems support article Requirements for trusted certificates in iOS 13 and macOS 10.15 support article About upcoming limits on trusted certificates support article Apple’s Certificate Transparency policy support article What’s new for enterprise in iOS 18 support article — This discusses new key usage requirements. Prepare your network environment for stricter security requirements support article — This is primarily of interest to folks developing management software, for example, an MDM server. Technote 2232 HTTPS Server Trust Evaluation Technote 2326 Creating Certificates for TLS Testing QA1948 HTTPS and Test Servers Miscellaneous: More network-related forums tags: 5G, QUIC, Bonjour On FTP forums post Using the Multicast Networking Additional Capability forums post Investigating Network Latency Problems forums post Share and Enjoy — Quinn “The Eskimo!” @ Developer Technical Support @ Apple let myEmail = "eskimo" + "1" + "@" + "apple.com" [1] This video is no longer available from Apple, but the URL should help you locate other sources of this info.

Given a directory path (or NSURL) I need to get the total number of files/documents in that directory - recursively - as fast and light as possible. I don't need to list the files, and not filter them. All the APIs I found so far (NSFileManger, NSURL, NSDirectoryEnumerator) collect too much information, and those who are recursive - are aggregating the whole hierarchy before returning. If applied to large directory - this both implies a high CPU peak and slow action, and a huge memory impact - even if transient. My question: What API is best to use to accomplish this count, must I scan recursively the hierarchy? Is there a "lower level" API I could use that is below NSFileManager that provides better performance? One time in the middle-ages, I used old MacOS 8 (before MacOS X) file-system APIs that were immensely fast and allowed doing this without aggregating anything. I write my code in Objective-C, using latest Xcode and MacOS and of course ARC.

Hi, I'm trying to create a custom TextField component where we can have our own custom FormatStyle as a param and then it will change the value binding according to the FormatStyle. It worked with State<Any?> like for example $textValue. But when I use .constant(2000) for instance, the Formatting doesn't work. So is there any way to detect whether the value param is constant or not? Thank you.

Is anyone else seeing 403 errors for PCC VRE when trying to pull assets for Release 41303? My pccvre audit of the Transparency Log passes (valid root digests for 41385), but the download fails consistently on specific CDN URLs: Failed to download SW release asset... response: 403 I’ve verified csrutil allow-research-guests is active and the license is accepted. Release 41385 seems fine, but 41303 is a brick wall. Is this a known pull-back or a CDN permissions sync issue?

The file ~/.CFUserTextEncoding contained a string which I can't understand. It's recreated when a user log in. I had found that the result of CoreFoundation.CFStringGetSystemEncoding() is affected by the content of this file. What is this file used for?

There appears to be a data loss bug in NSFileWrapper on macOS 26.4. It may have been around longer but I just never noticed ... So I write a RTFD file wrapper: NSFileWrapper *rtfd = [attributedString RTFDFileWrapperFromRange:NSMakeRange(0, attributedString.length) documentAttributes:@{NSDocumentTypeDocumentAttribute:NSRTFDTextDocumentType}]; Now IF I use -writeToURL:options:originalContentsURL:error: without using the NSFileWrapperWritingAtomic option and I pass in an existing URL, the followings happens: -The method returns NO and populates the NSError with NSFileWriteFileExistsError, as expected. This is what I want. -BUT the existing file is nuked. It just disappears. Foundation kills it. Poof. Another thing I gotta workaround. Getting pretty ridiculous, I must say. Just my lucky day I guess. It would be wonderful if I could work on my own features and fixing my own bugs.

I logged in to macOS with my localization language. try to perform following code. but always get "Documents". What do I miss? Apple Swift version 5.2.4 macOS 10.15.6 Xcode 11.6 code let paths = NSSearchPathForDirectoriesInDomains(.documentDirectory, .userDomainMask, true) if paths.count &gt; 0 {     let doc = FileManager().displayName(atPath: paths[0])     print(doc) } result Documents

I'm not sure if this is a recent issue, but I discovered NSIndexSet concurrency has a bug where not all indexes are enumerated. The following is a small sample demonstrating the issue in ObjC: NSLog(@"Hello, World! %@", NSProcessInfo.processInfo.operatingSystemVersionString); for (NSUInteger i = 0, n = 10; i < n; i++) { NSUInteger total = 301; NSMutableIndexSet *all = [NSMutableIndexSet indexSetWithIndexesInRange:NSMakeRange(0, total)]; NSIndexSet *pass = [all indexesWithOptions:NSEnumerationConcurrent passingTest:^BOOL(NSUInteger idx, BOOL *stop) { return true; }]; NSCAssert(all.count == pass.count, @"Mismatch #%ld %ld != %ld", i, all.count, pass.count); } Results on Version 26.4 (Build 25E246) look like Mismatch #0 297 != 301 Disabling concurrency (options:0) is a workaround. Feedback FB22447001

I published the latest update of my AppKit app in September with macOS 26.0. I just wanted to create a new update, but compiling on macOS 26.4 now fails because of the symbol NSTextAttachment.character which is referenced in my code. The error is Type 'NSTextAttachment' has no member 'character' I've never experienced before that a symbol suddenly is not available anymore without even a deprecation notice from one OS release to the next, let alone a minor release. Is this a bug in macOS or Xcode, or should I start worrying about symbols becoming unavailable anytime?

Nothing ruins the vibe of a clean file like a yellow warning banner, especially for something that was working perfectly fine yesterday. The "problem" isn't that your code is broken; it’s just that Apple is getting stricter about text encodings in the latest OS versions. They want you to explicitly state how the file should be read (e.g., UTF-8) rather than letting the system guess. On line 30, you just need to add the encoding parameter. For 99% of text files, .utf8 is what you want. Change this: let contents = try String(contentsOf: fileURL) To this: let contents = try String(contentsOf: fileURL, encoding: .utf8) Why is this happening? The Deprecation: As of macOS 15 (and iOS 18), the version of String(contentsOf:) that doesn't require an encoding is officially deprecated. The Logic: Without an explicit encoding, the system tries to "guess" if the file is UTF-8, Windows-1252, etc. If it guesses wrong, you get weird symbols or a crash. By forcing you to add , encoding: .utf8, Apple ensures your code is more predictable and stable. Once you add that one extra argument, that warning should vanish instantly!

Upgraded to Tahoe 26.4 and Xcode 26.4 and realized Xcode is missing the documentation for Foundation. Occasionally, if other (not yet missing) documentation references a Foundation entity, such as a type, clicking on it may open in a web browser pointing to the externally hosted Apple documentation. Anyone else experiencing this or have a workaround (perhaps the documentation files are on disk but were somehow lost / disconnected from the Xcode doc browser)? I checked the release notes for 26.4 and for 26.3 but did not find a mention of anything like that. Filed an issue with Apple, please do too if you are affected so hopefully it will see some love and lead to restoring the documentation. Edited: found some possibly related files in my ~/Library and the newer version v302 (26.4 related, I think, is considerably smaller): du -sh ~/Library/Developer/Xcode/DocumentationCache/* | awk -F/ '{print $NF "\t" $1}' v296 1.0G v302 507M

The documentation for NSURL -URLByAppendingPathComponent: states: "Returns a new URL by appending a path component to the original URL." Path component is singular. But this "works" : NSURL *testURL = [applicationsDirectory URLByAppendingPathComponent:@"Evil/../../" isDirectory:YES]; So my questions are: One) Was it always this way? I can't recall if it was like this before the Foundation rewrite and I just never stumbled across? and Two) Is it intended behavior? The API seems to suggest that you append one path component on the url with this method. But I guess you can append as many as you want?

I'd like to create a small helper app for new students do read/write User default settings. Since it was not possible using the UserDefaults class I decided to use the "/usr/bin/defaults". Unfortuntely it seems not to return anything. Debug output shows "Got data: 0 bytes" Here is a sample code: import SwiftUI func readDefaults(domain : String, key :String) -> String { let cmdPath = "/usr/bin/defaults" //let cmdPath = "/bin/ls" let cmd = Process() let pipe = Pipe() cmd.standardOutput = pipe cmd.standardError = pipe cmd.executableURL = URL(fileURLWithPath: cmdPath, isDirectory: false, relativeTo: nil) cmd.arguments = ["read", domain, key] //cmd.arguments = ["/", "/Library"] print("Shell command: \(cmdPath) \(cmd.arguments?.joined(separator: " ") ?? "")") var d : Data? do { try cmd.run() d = pipe.fileHandleForReading.readDataToEndOfFile() cmd.waitUntilExit() } catch let e as NSError { return "ERROR \(e.code): \(e.localizedDescription)" } catch { return "ERROR: call failed!" } // get pipe output and write is to stdout guard let d else { return "ERROR: Can't get pipe output from command!" } print("Got data: \(d)") if let s = String(data: d, encoding: String.Encoding.utf8) { print("Got result: \(s)") return s } else { return "ERROR: No output from pipe." } } struct ContentView: View { let foo = readDefaults(domain: "com.apple.Finder", key: "ShowHardDrivesOnDesktop") var body: some View { VStack { Text("ShowHardDrivesOnDesktop: \(foo.description)") } .padding() } } #Preview { ContentView() } This code works well e.g. for "ls" when the comments are changed for cmdPath and cmd.arguments. What do I miss in order to get it working with defaults?

A user of my app reported that when my app copies files from a QNAP NAS to a folder on their Mac, they get the error "Result too large". When copying the same files from the Desktop, it works. I asked them to reproduce the issue with the sample code below and they confirmed that it reproduces. They contacted QNAP for support who in turn contacted me saying that they are not sure they can do anything about it, and asking if Apple can help. Both the app user and QNAP are willing to help, but at this point I'm also unsure how to proceed. Can someone at Apple say anything about this? Is this something QNAP should solve, or is this a bug in macOS? P.S.: I've had users in the past who reported the same issue with other brands, mostly Synology. import Cocoa @main class AppDelegate: NSObject, NSApplicationDelegate { func applicationDidFinishLaunching(_ aNotification: Notification) { let openPanel = NSOpenPanel() openPanel.canChooseDirectories = true openPanel.runModal() let source = openPanel.urls[0] openPanel.canChooseFiles = false openPanel.runModal() let destination = openPanel.urls[0] do { try copyFile(from: source, to: destination.appendingPathComponent(source.lastPathComponent, isDirectory: false)) } catch { NSAlert(error: error).runModal() } NSApp.terminate(nil) } private func copyFile(from source: URL, to destination: URL) throws { if try source.resourceValues(forKeys: [.isDirectoryKey]).isDirectory == true { try FileManager.default.createDirectory(at: destination, withIntermediateDirectories: false) for source in try FileManager.default.contentsOfDirectory(at: source, includingPropertiesForKeys: nil) { try copyFile(from: source, to: destination.appendingPathComponent(source.lastPathComponent, isDirectory: false)) } } else { try copyRegularFile(from: source, to: destination) } } private func copyRegularFile(from source: URL, to destination: URL) throws { let state = copyfile_state_alloc() defer { copyfile_state_free(state) } var bsize = UInt32(16_777_216) if copyfile_state_set(state, UInt32(COPYFILE_STATE_BSIZE), &bsize) != 0 { throw NSError(domain: NSPOSIXErrorDomain, code: Int(errno)) } else if copyfile_state_set(state, UInt32(COPYFILE_STATE_STATUS_CB), unsafeBitCast(copyfileCallback, to: UnsafeRawPointer.self)) != 0 { throw NSError(domain: NSPOSIXErrorDomain, code: Int(errno)) } else if copyfile(source.path, destination.path, state, copyfile_flags_t(COPYFILE_DATA | COPYFILE_SECURITY | COPYFILE_NOFOLLOW | COPYFILE_EXCL | COPYFILE_XATTR)) != 0 { throw NSError(domain: NSPOSIXErrorDomain, code: Int(errno)) } } private let copyfileCallback: copyfile_callback_t = { what, stage, state, src, dst, ctx in if what == COPYFILE_COPY_DATA { if stage == COPYFILE_ERR { return COPYFILE_QUIT } } return COPYFILE_CONTINUE } }

Sort of a continuation of - https://developer.apple.com/forums/thread/813641 I've made a great effort to get NSURL -getResourceValue:forKey: calls etc off the main thread. Great progress. So now I'm working with a file on a really slow network volume I discovered a little hang and luckily enough I'm attached to the debugger so I paused that thing. I see where I'm at. It is: NSPathControl's setURL:. It goes a little something like this: in realpath$DARWIN_EXTSN () +fileSystemRealPath () +[FSNode(SandboxChecks) canAccessURL:withAuditToken:operation:] () +FSNode(SandboxChecks) canReadFromSandboxWithAuditToken:] () LaunchServices::URLPropertyProvider::prepareLocalizedNameValue () LaunchServices::URLPropertyProvider::prepareValues () prepareValuesForBitmap () FSURLCopyResourcePropertiesForKeysInternal () CFURLCopyResourcePropertiesForKeys () -[NSURL resourceValuesForKeys:error:] () in function signature specialization <Arg[1] = Dead> of Foundation._NSFileManagerBridge.displayName(atPath: Swift.String) -> Swift.String () in displayName () -[NSPathCell _autoUpdateCellContents] () -[NSPathCell setURL:] () Could maybe, NSPathControl get the display name etc. asynchronously? and maybe just stick raw path components in as a placeholder while it is reading async? Or something like that? If I can preload the resource keys it needs I would but once the NSURL asks on the main main thread I think it will just dump the cache out, per the run loop rules.

When iterating over a CMSensorDataList (which conforms to NSFastEnumeration) returned by CoreMotion's CMSensorRecorder's accelerometerData(from:to:) method, we sometimes see the crash below, with the frame above pointing to the close brace of the for loop iterating over the list. 0 CoreMotion 0x000000019fcf01dc CLInternalGetPinnedLocationAuthorizationState + 423316 1 CoreMotion 0x000000019fcf036b CLInternalGetPinnedLocationAuthorizationState + 423715 2 CoreMotion 0x000000019fcf02cb CLInternalGetPinnedLocationAuthorizationState + 423555 3 CoreMotion 0x000000019fbb8553 CLMotionActivity::isStatic() const + 1751823 It has been incredibly difficult to reproduce. We managed to reproduce a similar crash stack twice in a separate app that misused accelerometerData(from:to:) by providing a from and to Date that were more than 12 hours apart and iterating over the returned data, but it only occurred twice in many hours of testing. We hope to know if this could be a bug in Core Motion or it is definitely in our SDK, or if there is any way to fail gracefully in this scenario.

So I'm in the middle of an asynchronous file operation. I publish an NSProgress and it displays wonderfully in Finder. But it is a folder and while the operation is in progress the user should not be allowed to enter it, modify it, etc, while the work is being done. I want to do this to protect the user from doing something silly. But Finder does not prevent the selection with the published progress. And while it would be kind of dumb to do - the user can just go about adding/removing contents to the folder while it has progress. If I remember correctly publishing an NSProgress did use to prevent the file from being selectable in Finder until either the progress finished or my app is quit (or maybe not)? But now the user is free to select, edit, modify during progress which could cause problems if the user does something unexpectedly silly. Is there a way to mark the file 'unselectable' with the published progress? Thanks in advance.

The man page of copyfile sates the following: COPYFILE_CLONE [..] Note also that there is no support for cloning directories" COPYFILE_CLONE_FORCE [...] Note also that there is no support for cloning directories: if a directory is provided as the source, an error will be returned. Now the man page for clonefile: > Cloning directories with these functions is strongly discouraged. Use copyfile(3) to clone directories instead. -- So am I to enumerate the content of a directory build subfolders along the way in the target destination and clone each file inside individually? If I recall NSFileManager seems to clone a large directory instantly (edit actually I remembered wrong NSFileManager does not do this. Finder seems to copy instead of clone as well). On further inspection, clonefile states that it can do this, but it is discouraged. Interesting. I wonder why. If src names a directory, the directory hierarchy is cloned as if each item was cloned individually. However, the use of clonefile(2) to clone directory hierarchies is strongly discouraged. Use copyfile(3) instead for copying directories. P.S. - Forgive me if I posting this in the wrong category, I couldn't find a "category" in the list of available categories on these forums that seems appropriate for this question.

I am developing an iOS/iPadOS application and have encountered some behavior regarding Files App and security-scoped bookmarks that I would like to clarify. Additionally, I would like to report some behavior which might include a potential issue. Question1: Accessing deleted files via bookmark (Specification clarification) Our app saves file URLs as bookmarks, which file that user has selected on Files App or app-created so to open a file which user has modified previously in the next launch. When a user deletes a file in Files App (moves a file to Recently Deleted), the app can still resolve the bookmark and access the file for read/write operations. Is this behavior intended? In other words, is it correct that a bookmark can access a file that has been deleted in Files App but not permanently removed? Question2: Overwriting a file in Recently Deleted (Potential bug) We noticed that overwriting a file in Recently Deleted behaves differently depending on the method used. Current implementation 1.Create a temporary file in the same directory 2.Write content to the temporary file 3.Delete the original file ([NSFileManager removeItemAtURL:error:]) 4.Move the temporary file to the original file path ([NSFileManager moveItemAtURL:toURL:error:]) Result: The file disappears from Files App Recently Deleted. In contrast, using [NSFileManager replaceItemAtURL:withItemAtURL:] keeps the file visible in Recently Deleted. Is this difference designed behavior? If not, this may be a bug. Question3: Detecting files in Recently Deleted We want to detect whether a file resides in Recently Deleted, but we cannot find a reliable and officially supported method. Recently Deleted files appear under .Trash, but using the path alone is not a reliable method. We have tried the following APIs without success: [NSURL getResourceValue:forKey:NSURLIsHiddenKey error:] [NSURL checkResourceIsReachableAndReturnError:] [NSFileManager fileExistsAtPath:] [NSFileManager isReadableFileAtPath:] [NSFileManager getRelationship:ofDirectory:NSTrashDirectory inDomain:NSUserDomainMask toItemAtURL:error:] We could not obtain the Recently Deleted folder URL using standard APIs. [NSFileManager URLsForDirectory:NSTrashDirectory inDomains:NSUserDomainMask] [NSFileManager URLForDirectory:NSTrashDirectory inDomain:NSUserDomainMask appropriateForURL:url create:error:] Could you advise a safe and supported way to detect Recently Deleted files properly by the app?

I'll try to ask a question that makes sense this time :) . I'm using the following method on NSFileManager: (BOOL) getRelationship:(NSURLRelationship *) outRelationship ofDirectoryAtURL:(NSURL *) directoryURL toItemAtURL:(NSURL *) otherURL error:(NSError * *) error; Sets 'outRelationship' to NSURLRelationshipContains if the directory at 'directoryURL' directly or indirectly contains the item at 'otherURL', meaning 'directoryURL' is found while enumerating parent URLs starting from 'otherURL'. Sets 'outRelationship' to NSURLRelationshipSame if 'directoryURL' and 'otherURL' locate the same item, meaning they have the same NSURLFileResourceIdentifierKey value. If 'directoryURL' is not a directory, or does not contain 'otherURL' and they do not locate the same file, then sets 'outRelationship' to NSURLRelationshipOther. If an error occurs, returns NO and sets 'error'. So this method falsely returns NSURLRelationshipSame for different directories. One is empty, one is not. Really weird behavior. Two file path urls pointing to two different file paths have the same NSURLFileResourceIdentifierKey? Could it be related to https://developer.apple.com/forums/thread/813641 ? One url in the check lived at the same file path as the other url at one time (but no longer does). No symlinks or anything going on. Just plain directory urls. And YES calling -removeCachedResourceValueForKey: with NSURLFileResourceIdentifierKey causes proper result of NSURLRelationshipOther to be returned. And I'm doing the check on a background queue.