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. Available trusted root certificates for Apple operating systems support article Requirements for trusted certificates in iOS 13 and macOS 10.15 support article About upcoming limits on trusted certificates support article Apple’s Certificate Transparency policy support article What’s new for enterprise in iOS 18 support article — This discusses new key usage requirements. Technote 2232 HTTPS Server Trust Evaluation Technote 2326 Creating Certificates for TLS Testing QA1948 HTTPS and Test Servers Miscellaneous: More network-related forums tags: 5G, QUIC, Bonjour On FTP forums post Using the Multicast Networking Additional Capability forums post Investigating Network Latency Problems forums post 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.

We are getting a crash _dispatch_assert_queue_fail when the cancellationHandler on NSProgress is called. We do not see this with iOS 17.x, only on iOS 18. We are building in Swift 6 language mode and do not have any compiler warnings. We have a type whose init looks something like this: init( request: URLRequest, destinationURL: URL, session: URLSession ) { progress = Progress() progress.kind = .file progress.fileOperationKind = .downloading progress.fileURL = destinationURL progress.pausingHandler = { [weak self] in self?.setIsPaused(true) } progress.resumingHandler = { [weak self] in self?.setIsPaused(false) } progress.cancellationHandler = { [weak self] in self?.cancel() } When the progress is cancelled, and the cancellation handler is invoked. We get the crash. The crash is not reproducible 100% of the time, but it happens significantly often. Especially after cleaning and rebuilding and running our tests. * thread #4, queue = 'com.apple.root.default-qos', stop reason = EXC_BREAKPOINT (code=1, subcode=0x18017b0e8) * frame #0: 0x000000018017b0e8 libdispatch.dylib`_dispatch_assert_queue_fail + 116 frame #1: 0x000000018017b074 libdispatch.dylib`dispatch_assert_queue + 188 frame #2: 0x00000002444c63e0 libswift_Concurrency.dylib`swift_task_isCurrentExecutorImpl(swift::SerialExecutorRef) + 284 frame #3: 0x000000010b80bd84 MyTests`closure #3 in MyController.init() at MyController.swift:0 frame #4: 0x000000010b80bb04 MyTests`thunk for @escaping @callee_guaranteed @Sendable () -> () at <compiler-generated>:0 frame #5: 0x00000001810276b0 Foundation`__20-[NSProgress cancel]_block_invoke_3 + 28 frame #6: 0x00000001801774ec libdispatch.dylib`_dispatch_call_block_and_release + 24 frame #7: 0x0000000180178de0 libdispatch.dylib`_dispatch_client_callout + 16 frame #8: 0x000000018018b7dc libdispatch.dylib`_dispatch_root_queue_drain + 1072 frame #9: 0x000000018018bf60 libdispatch.dylib`_dispatch_worker_thread2 + 232 frame #10: 0x00000001012a77d8 libsystem_pthread.dylib`_pthread_wqthread + 224 Any thoughts on why this is crashing and what we can do to work-around it? I have not been able to extract our code into a simple reproducible case yet. And I mostly see it when running our code in a testing environment (XCTest). Although I have been able to reproduce it running an app a few times, it's just less common.

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 } }

Hi there, I uploaded an update bundle for the posted app, but I got a rejection message. ITMS-90048: This bundle is invalid - Your archive contains paths that are not allowed: [._Symbols] The XCode version I'm using is 16.2, and I've been trying to find a route using Run Script and Finder, but I don't know what the hell it is about. Does anybody know what could cause this issue? Any help would be appreciated. Thanks.

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.

I have an iOS app with ExtensionFoundation. It runs well on my local device, but when I upload on the AppStore it gets rejected with: Validation failed Invalid Info.plist value. The value of the EXExtensionPointIdentifier key, AsheKube.app.a-Shell.localWebServer, in the Info.plist of “a-Shell.app/Extensions/localWebServer.appex” is invalid. Please refer to the App Extension Programming Guide at https://developer.apple.com/library/content/documentation/General/Conceptual/ExtensibilityPG/Action.html#/apple_ref/doc/uid/TP40014214-CH13-SW1. (ID: ae8dd1dd-8caf-4a48-9651-7a225faed4eb) The Info.plist in my Extension is: <?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd"> <plist version="1.0"> <dict> <key>EXAppExtensionAttributes</key> <dict> <key>EXExtensionPointIdentifier</key> <string>com.example.example-extension</string> </dict> </dict> </plist> so the Info.plist that causes the issue has been automatically generated by Xcode. I can access it as well, and it says: { "BuildMachineOSBuild" => "25A354" "CFBundleDevelopmentRegion" => "en" "CFBundleDisplayName" => "localWebServerExtension" "CFBundleExecutable" => "localWebServer" "CFBundleIdentifier" => "AsheKube.app.a-Shell.localWebServerExtension" "CFBundleInfoDictionaryVersion" => "6.0" "CFBundleName" => "localWebServer" "CFBundlePackageType" => "XPC!" "CFBundleShortVersionString" => "1.0" "CFBundleSupportedPlatforms" => [ 0 => "iPhoneOS" ] "CFBundleVersion" => "1" "DTCompiler" => "com.apple.compilers.llvm.clang.1_0" "DTPlatformBuild" => "23A339" "DTPlatformName" => "iphoneos" "DTPlatformVersion" => "26.0" "DTSDKBuild" => "23A339" "DTSDKName" => "iphoneos26.0" "DTXcode" => "2601" "DTXcodeBuild" => "17A400" "EXAppExtensionAttributes" => { "EXExtensionPointIdentifier" => "AsheKube.app.a-Shell.localWebServer" } "MinimumOSVersion" => "26.0" "NSHumanReadableCopyright" => "Copyright © 2025 AsheKube. All rights reserved." "UIDeviceFamily" => [ 0 => 1 1 => 2 ] "UIRequiredDeviceCapabilities" => [ 0 => "arm64" ] } What should I do to be able to upload on the AppStore?

All the threads only contain system calls. The crashed thread only contains a single call to my app's code which is main.swift:13. What could cause such a crash? crash.crash

I have been working on updating an old app that makes extensive use of Objective-C's NSTask. Now using Process in Swift, I'm trying to gather updates as the process runs, using readabilityHandler and availableData. However, my process tends to exit before all data has been read. I found this post entitled "Running a Child Process with Standard Input and Output" but it doesn't seem to address gathering output from long-running tasks. Is there a straightforward way to gather ongoing output from a long running task without it prematurely exiting?

We are testing our existing live build, which was prepared with Xcode 16.2, on iOS 26 beta for experience assurance and found that the [[UIDevice currentDevice] systemVersion] API is returning iOS 19 instead of the expected version iOS 26. Has anyone else observed this issue?

Environment: Xcode 26 iOS 26 Also tested on iOS 18 (working correctly) Description: I'm experiencing a behavior change with URL(fileURLWithPath:) when the filename starts with a tilde (~) character. On iOS 18, passing a filename like ~MyFile.txt to URL(fileURLWithPath:) treats the tilde as a literal character. However, on iOS 26, the same code resolves the tilde as the home directory, resulting in unexpected output. Minimal Example: let filename = "~MyFile.txt" let url = URL(fileURLWithPath: filename) print(url.lastPathComponent) Expected Result (iOS 18): ~MyFile.txt Actual Result (iOS 26): 924AF0C4-C3CD-417A-9D5F-733FBB8FCF29 The tilde is being resolved to the app's container directory, and lastPathComponent returns the container UUID instead of the filename. Questions: 1. Is this an intentional behavior change in iOS 26? 2. Is there documentation about this change? 3. What is the recommended approach for extracting filename components when the filename may contain special characters like ~? Workaround: Using NSString.lastPathComponent works correctly on both iOS versions: let filename = "~MyFile.txt" let result = (filename as NSString).lastPathComponent // Returns: "~MyFile.txt" ✅ Is this the recommended approach going forward?

Greetings, I would like to understand this URLCache behavior for two different requests to the same end point but with a different header value. Here is a code with comment explaining the behavior. // Create a request to for a url. let url = URL(string: "https://&lt;my url&gt;?f=json")! var request = URLRequest(url: url) // Set custom header with a value. request.setValue("myvalue", forHTTPHeaderField: "CustomField") // Send request to get the response. let (data, response) = try await URLSession.shared.data(for: request) print("data: \(String(describing: String(data: data, encoding: .utf8)))") print("response: \(response)") // Create second request to the same url but with different value of custom header field. var request2 = URLRequest(url: url) request2.setValue("newvalue", forHTTPHeaderField: "CustomField") // Check the URL cache for second request and it returns the response // of the first request even though the second request has different header value. let cachedResponse = URLCache.shared.cachedResponse(for: request2) print("cachedResponse: \(cachedResponse?.response)") Is this a bug in URLCache that request headers are not matched while returning the response? Is this an expected behavior? If yes, why?

Hey, I am just about to prepare my app for Swift 6, and facing the issue that UserDefaults is not Sendable. The documentation states that its thread safe, so I am wondering, why is it not marked as Sendable? Was it just forgotten? Is it safe to mark it as nonisolated(unsafe) or @unchecked Sendable?

A user of my app reported that when trying to remove a file it always fails with the error "file couldn't be removed because you don't have permission to access it (Cocoa Error Domain 513)". After some testing, we found out that it's caused by trying to delete non-empty directories. I'm using FileManager.removeItem(atPath:) which has worked fine for many years, but it seems that with their particular NAS, it doesn't work. I could work around this by checking if the file is a directory, and if it is, enumerating the directory and remove each contained file before removing the directory itself. But shouldn't this already be taken care of? In the source code of FileManager I see that for Darwin platforms it calls removefile(pathPtr, state, removefile_flags_t(REMOVEFILE_RECURSIVE)) so it seems that it should already work. Is the REMOVEFILE_RECURSIVE flag perhaps ignored by the device? But then, is the misleading "you don't have permission to access the file" error thrown by the device or by macOS? For the FileManager source code, see https://github.com/swiftlang/swift-foundation/blob/1d5d70997410fc8b7700c8648b10d6fc28194202/Sources/FoundationEssentials/FileManager/FileOperations.swift#L444

Since macOS 26.1, creating bookmark data based on a NSOpenPanel URL, does not return the expected bookmark data when the selected source concerns a Windows NTFS fileshare. When the returned data is being resolved, the returned URL points to the local drive of the current Mac. Which is of course super confusing for the user. This issue did not occur in macOS 26.0 and older. In essence, the following code line with 'url' based on an URL from a NSOpenPanel after selecting the root of a Windows NTFS share, creates an incorrect bookmark in macOS 26.1: let bookmark = try url.bookmarkData(options: .withSecurityScope, includingResourceValuesForKeys: nil, relativeTo: nil) I have tested this on two different Macs with macOS 26.1 with two different Windows PC both hosting NTFS files shares via SMB. My questions: Have anyone else encountered this issue in macOS 26? Perhaps even with other fileshare types? Is there a workaround or some new project configuration needed in Xcode to get this working?

We are developing an iOS application that is interacting with HTTP APIs that requires us to put a unique UUID (a nonce) as an header on every request (obviously there's more than that, but that's irrilevant to the question here). If the same nonce is sent on two subsequent requests the server returns a 412 error. We should avoid generating this kind of errors as, if repeated, they may be flagged as a malicious activity by the HTTP APIs. We are using URLSession.shared.dataTaskPublisher(for: request) to call the HTTP APIs with request being generated with the unique nonce as an header. On our field tests we are seeing a few cases of the same HTTP request (same nonce) being repeated a few seconds on after the other. Our code has some retry logic only on 401 errors, but that involves a token refresh, and this is not what we are seeing from logs. We were able to replicate this behaviour on our own device using Network Link Conditioner with very bad performance, with XCode's Network inspector attached we can be certain that two HTTP requests with identical headers are actually made automatically, the first request has an "End Reason" of "Retry", the second is "Success" with Status 412. Our questions are: can we disable this behaviour? can we provide a new request for the retry (so that we can update headers)? Thanks, Francesco

I have discovered a gap in my understanding of user selected URLs in iOS, and I would be grateful if someone can put me right please. My understanding is that a URL selected by a user can be accessed by calling url.startAccessingSecurityScopedResource() call. Subsequently a call to stopAccessingSecurityScopedResource() is made to avoid sandbox memory leaks. Furthermore, the URL can be saved as a bookmark and reconstituted when the app is run again to avoid re-asking permission from the user. So far so good. However, I have discovered that a URL retrieved from a bookmark can be accessed without the call to url.startAccessingSecurityScopedResource(). This seems contrary to what the documentation says here So my question is (assuming this is not a bug) why not save and retrieve the URL immediately in order to avoid having to make any additional calls to url.startAccessingSecurityScopedResource? Bill Aylward You can copy and paste the code below into a new iOS project to illustrate this. Having chosen a folder, the 'Summarise folder without permission' button fails as expected, but once the 'Retrieve URL from bookmark' has been pressed, it works fine. import SwiftUI import UniformTypeIdentifiers struct ContentView: View { @AppStorage("bookmarkData") private var bookmarkData: Data? @State private var showFolderPicker = false @State private var folderUrl: URL? @State private var folderReport: String? var body: some View { VStack(spacing: 20) { Text("Selected folder: \(folderUrl?.lastPathComponent ?? "None")") Text("Contents: \(folderReport ?? "Unknown")") Button("Select folder") { showFolderPicker.toggle() } Button("Deselect folder") { folderUrl = nil folderReport = nil bookmarkData = nil } .disabled(folderUrl == nil) Button("Retrieve URL from bookmark") { retrieveFolderURL() } .disabled(bookmarkData == nil) Button("Summarise folder with permission") { summariseFolderWithPermission(true) } .disabled(folderUrl == nil) Button("Summarise folder without permission") { summariseFolderWithPermission(false) } .disabled(folderUrl == nil) } .padding() .fileImporter( isPresented: $showFolderPicker, allowedContentTypes: [UTType.init("public.folder")!], allowsMultipleSelection: false ) { result in switch result { case .success(let urls): if let selectedUrl = urls.first { print("Processing folder: \(selectedUrl)") processFolderURL(selectedUrl) } case .failure(let error): print("\(error.localizedDescription)") } } .onAppear() { guard folderUrl == nil else { return } retrieveFolderURL() } } func processFolderURL(_ selectedUrl: URL?) { guard selectedUrl != nil else { return } // Create and save a security scoped bookmark in AppStorage do { guard selectedUrl!.startAccessingSecurityScopedResource() else { print("Unable to access \(selectedUrl!)"); return } // Save bookmark bookmarkData = try selectedUrl!.bookmarkData(options: .minimalBookmark, includingResourceValuesForKeys: nil, relativeTo: nil) selectedUrl!.stopAccessingSecurityScopedResource() } catch { print("Unable to save security scoped bookmark") } folderUrl = selectedUrl! } func retrieveFolderURL() { guard let bookmarkData = bookmarkData else { print("No bookmark data available") return } do { var isStale = false let url = try URL( resolvingBookmarkData: bookmarkData, options: .withoutUI, relativeTo: nil, bookmarkDataIsStale: &isStale ) folderUrl = url } catch { print("Error accessing URL: \(error.localizedDescription)") } } func summariseFolderWithPermission(_ permission: Bool) { folderReport = nil print(String(describing: folderUrl)) guard folderUrl != nil else { return } if permission { print("Result of access requrest is \(folderUrl!.startAccessingSecurityScopedResource())") } do { let contents = try FileManager.default.contentsOfDirectory(atPath: folderUrl!.path) folderReport = "\(contents.count) files, the first is: \(contents.first!)" } catch { print(error.localizedDescription) } if permission { folderUrl!.stopAccessingSecurityScopedResource() } } }

I have created a sample app which read/write from a network file. When the file was attempted to open (using open Linux API), connection to network file was lost. The thread which was stuck on the open method, returns after a long time. It was observed that for macOS, the maximum return time of the thread was around 10 mins, whereas in Windows and Linux, the maximum timeout was 60 sec and 90 sec. macOS has a very large timeout before returning the thread with a network failure error. Is this by designed and expected? With a large timeout as 10mins, it's difficult to respond swiftly back to the user.

On iOS 18 and lower version, my application supports automatically switching to [System settings - Personal Hotspot] directly. But on iOS 26, my application will be redirected to [System settings- Apps]. Does iOS 26 disable the behavior of directly jumping to the system hotspot page? If support, could you share the API for iOS 26?

I have an Xcode app where currently txt files in the project display text data as a list. I can search through the lists and have buttons that will swap between different lists of information that you can look through. The next task is I have URL connections to docx files on a SharePoint site. I am trying to use an URLsession function to connect to the URL links to download the documents to the document directory then have the application read the doc information to then be displayed as the txt info would. The idea is that the docx files are a type of online update version of the data. So when the app is used and on wifi, the app can update the list data with the docx files. I have code set up that should access the URL files but I am struggling to figure out how to read the data and access from this Documents directory. I have been looking online and so far I am at a loss on where to go here. If anyone can help or provide some insight I would greatly appreciate it. I can try and provide code samples to help explain things if that is needed.

The documentation says: The caching behavior of the NSURL and CFURL APIs differ. For NSURL, all cached values (not temporary values) are automatically removed after each pass through the run loop. You only need to call the removeCachedResourceValueForKey: method when you want to clear the cache within a single execution of the run loop. The CFURL functions, on the other hand, do not automatically clear cached resource values. The client has complete control over the cache lifetimes, and you must use CFURLClearResourcePropertyCacheForKey or CFURLClearResourcePropertyCache to clear cached resource values. https://developer.apple.com/documentation/foundation/nsurl/removeallcachedresourcevalues()?language=objc Is this really true? In my experience I've had to explicitly remove cached resource values via -removeAllCachedResourceValues or removeCachedResourceValueForKey: otherwise the URL contains stale values. For example on a URL that no longer exists I attempted to read NSURLIsHiddenKey and the last value was already cached. Instead of getting a NSFileNoSuchFileError I get the old cache value unless explicitly call -removeCachedResourceValueForKey: first and I'm fairly certain the value was cached on a previous run loop churn.

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.