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NSTableView is unresponsive when inside a modal window shown in DispatchQueue.main.async
In my app I have a background task performed on a custom DispatchQueue. When it has completed, I update the UI in DispatchQueue.main.async. In a particular case, the app then needs to show a modal window that contains a table view, but I have noticed that when scrolling through the tableview, it only responds very slowly. It appears that this happens when the table view in the modal window is presented in DispatchQueue.main.async. Presenting it in perform(_:with:afterDelay:) or in a Timer.scheduledTimer(withTimeInterval:repeats:block:) on the other hand works. Why? This seems like an ugly workaround. I created FB7448414 in November 2019 but got no response. @NSApplicationMain class AppDelegate: NSObject, NSApplicationDelegate { func applicationDidFinishLaunching(_ aNotification: Notification) { let windowController = NSWindowController(window: NSWindow(contentViewController: ViewController())) // 1. works // runModal(for: windowController) // 2. works // perform(#selector(runModal), with: windowController, afterDelay: 0) // 3. works // Timer.scheduledTimer(withTimeInterval: 0, repeats: false) { [self] _ in // self.runModal(for: windowController) // } // 4. doesn't work DispatchQueue.main.async { self.runModal(for: windowController) } } @objc func runModal(for windowController: NSWindowController) { NSApp.runModal(for: windowController.window!) } } class ViewController: NSViewController, NSTableViewDataSource, NSTableViewDelegate { override func loadView() { let tableView = NSTableView() tableView.dataSource = self tableView.delegate = self tableView.addTableColumn(NSTableColumn()) let scrollView = NSScrollView(frame: CGRect(x: 0, y: 0, width: 400, height: 400)) scrollView.documentView = tableView scrollView.hasVerticalScroller = true scrollView.translatesAutoresizingMaskIntoConstraints = false view = scrollView } func numberOfRows(in tableView: NSTableView) -> Int { return 100 } func tableView(_ tableView: NSTableView, viewFor tableColumn: NSTableColumn?, row: Int) -> NSView? { let view = NSTableCellView() let textField = NSTextField(labelWithString: "\(row)") textField.translatesAutoresizingMaskIntoConstraints = false view.addSubview(textField) NSLayoutConstraint.activate([textField.leadingAnchor.constraint(equalTo: view.leadingAnchor), textField.trailingAnchor.constraint(equalTo: view.trailingAnchor), textField.topAnchor.constraint(equalTo: view.topAnchor), textField.bottomAnchor.constraint(equalTo: view.bottomAnchor)]) return view } }
4
0
172
Jun ’25
How to create file system snapshots with fs_snapshot_create?
The online documentation for fs_snapshot_create, which is on a website which apparently I'm not allowed to link to on this forum, mentions that some entitlement is necessary, but doesn't specify which one. Searching online I found someone mentioning com.apple.developer.vfs.snapshot, but when adding this to my entitlement file and building my Xcode project, I get the error Provisioning profile "Mac Team Provisioning Profile: com.example.myApp" doesn't include the com.apple.developer.vfs.snapshot entitlement. Searching some more online, I found someone mentioning that one has to request this entitlement from DTS. Is this true? I couldn't find any official documentation. I actually want to make a snapshot of a user-selected directory so that my app can sync it to another volume while avoiding that the user makes changes during the sync process that would make the copy inconsistent. Would fs_snapshot_create be faster than traversing the chosen directory and creating clones of each nested file with filecopy and the flag COPYFILE_CLONE? Although I have the impression that only fs_snapshot_create could make a truly consistent snapshot.
13
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291
Jun ’25
Detect and wait until a file has been unzipped to avoid permission errors
In my app the user can select a source folder to be synced with a destination folder. The sync can also happen in response to a change in the source folder detected with FSEventStreamCreate. If the user unzips an archive in the source folder and the sync process begins before the unzip operation has completed, the sync can fail because of a "Permission denied" error. I assume this is related to the posix permissions of the extracted folder being 420 during the unzip operation and (in my case) 511 afterwards. Is there a way to detect than an unzip operation is in progress and wait until it has completed? I thought that using NSFileCoordinator would solve this issue, but unfortunately it's not the case. Since an unzip operation can last any amount of time, it's not ideal to just delay a sync by a fixed number of seconds and let the user deal with any error if the unzip operation takes longer. let openPanel = NSOpenPanel() openPanel.canChooseDirectories = true if openPanel.runModal() == .cancel { return } let url = openPanel.urls[0].appendingPathComponent("extracted", isDirectory: false) var error: NSError? NSFileCoordinator(filePresenter: nil).coordinate(readingItemAt: url, error: &error) { url in do { print(try FileManager.default.attributesOfItem(atPath: url.path).sorted(by: { $0.key.rawValue < $1.key.rawValue }).map({ ($0.key.rawValue, $0.value) })) try FileManager.default.contentsOfDirectory(at: url, includingPropertiesForKeys: nil) } catch { print(error) } } if let error = error { print("file coordinator error:", error) }
13
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239
May ’25
Xcode has high CPU usage when apparently doing nothing for hours
In 2020 I created FB7719215, which I updated several times (including just now) and in 2021 I created FB9204092, but the issue is still there: when I keep Xcode open (currently version 16.3), my battery drains much quicker, even when it's apparently idle. For instance, today I barely did anything in Xcode, but still it has been at a constant 90% CPU for the last hours, and I keep checking the battery percentage to check how much time I have left. Does anyone at Apple has an explanation, workaround and/or fix?
2
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128
May ’25
NSDocument doesn't autosave last changes
I had noticed an unsettling behaviour about NSDocument some years ago and created FB7392851, but the feedback didn't go forward, so I just updated it and hopefully here or there someone can explain what's going on. When running a simple document-based app with a text view, what I type before closing the app may be discarded without notice. To reproduce it, you can use the code below, then: Type "asdf" in the text view. Wait until the Xcode console logs "saving". You can trigger it by switching to another app and back again. Type something else in the text view, such as "asdf" on a new line. Quit the app. Relaunch the app. The second line has been discarded. Am I doing something wrong or is this a bug? Is there a workaround? class ViewController: NSViewController { @IBOutlet var textView: NSTextView! } class Document: NSDocument { private(set) var text = "" override class var autosavesInPlace: Bool { return true } override func makeWindowControllers() { let storyboard = NSStoryboard(name: NSStoryboard.Name("Main"), bundle: nil) let windowController = storyboard.instantiateController(withIdentifier: NSStoryboard.SceneIdentifier("Document Window Controller")) as! NSWindowController (windowController.contentViewController as? ViewController)?.textView.string = text self.addWindowController(windowController) } override func data(ofType typeName: String) throws -> Data { Swift.print("saving") text = (windowControllers.first?.contentViewController as? ViewController)?.textView.string ?? "" return Data(text.utf8) } override func read(from data: Data, ofType typeName: String) throws { text = String(decoding: data, as: UTF8.self) (windowControllers.first?.contentViewController as? ViewController)?.textView.string = text } }
Topic: UI Frameworks SubTopic: AppKit Tags:
17
0
508
May ’25
Crash in IndexSet.map during menu item validation in client report downloaded by Xcode
For many years I've had the following code to access the active objects of a table view in my App Store app: class MyViewController: NSViewController: NSMenuItemValidation { private var tableView: NSTableView! private var objects = [MyObject]() func numberOfRows(in tableView: NSTableView) -> Int { return objects.count } func tableView(_ tableView: NSTableView, viewFor tableColumn: NSTableColumn?, row: Int) -> NSView? { // make view for row } private var activeObjects: [MyObject] { return tableView?.activeRowIndexes.map({ objects[$0] }) ?? [] } func validateMenuItem(_ menuItem: NSMenuItem) -> Bool { let activeObjects = self.activeObjects ... } } extension NSTableView { var activeRowIndexes: IndexSet { return clickedRow == -1 || selectedRowIndexes.contains(clickedRow) ? selectedRowIndexes : IndexSet(integer: clickedRow) } } In one of the recent updates, I wanted to add some kind of header to the table view, so I decided to add a row at the beginning and offset the indexes by 1. func numberOfRows(in tableView: NSTableView) -> Int { return objects.count + 1 } func tableView(_ tableView: NSTableView, viewFor tableColumn: NSTableColumn?, row: Int) -> NSView? { if row == 0 { // make header view } else { // make view for row - 1 } } private var activeObjects: [MyObject] { return tableView?.activeRowIndexes.subtracting(IndexSet(integer: 0)).map({ objects[$0 - 1] }) ?? [] } But since I added this change, Xcode regularly downloads crash reports from clients crashing during menu item validation in IndexSet.map with reason Code 5 Trace/BPT trap: 5. I assumed that I was accessing an invalid array index, so I added some debug code: the crash report would then show the invalid index beside the crashed thread's name. private var activeObjects: [MyObject] { return tableView?.activeRowIndexes.subtracting(IndexSet(integer: 0)).map({ i in if !objects.indices.contains(i - 1) { Thread.current.name = (Thread.current.name ?? "") + ". Invalid index \(i - 1) for count \(objects.count)" preconditionFailure() } return objects[i - 1] }) ?? [] } But the crash reports for this new app version look just like the old ones and the thread name is not changed. Indeed, when recreating an invalid index access on my Mac, the crash report mentions Array._checkSubscript(_:wasNativeTypeChecked:), which does not appear in the crash reports downloaded by Xcode. Manually symbolicating the crash report also doesn't give any more information: all lines referring to my app code are resolved to either /<compiler-generated>:0 or MyViewController.swift:0. Apparently the problem is not an invalid array index, but something else. Does anybody have a clue what the problem could be? (Note: the crash report mentions Sequence.compactMap because now I'm effectively calling tableView?.activeRowIndexes.compactMap, but the same crash happened before when calling IndexSet.map, which would appear in the crash report as Collection.map.) crash2.crash
3
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108
May ’25
Overriding NSDocument.prepareSavePanel(_:) hides file format popup button
I would like to provide a default filename when saving a document depending on the document data. I thought I could do so by overriding NSDocument.prepareSavePanel(_:) and setting NSSavePanel.nameFieldStringValue, but simply implementing that method seems to hide the file format popup button shown by default (see image). Calling super doesn't help. Is it possible to set a default filename and keep the file format popup button? On macOS 15, I can toggle NSSavePanel.showsContentTypes, but how about macOS 14 and older?
Topic: UI Frameworks SubTopic: AppKit Tags:
5
0
233
Apr ’25
NSTableView.clickedRow sometimes is greater than number of rows
Xcode has been downloading many similar crash reports for my app for some time now, related to an index out of range runtime exception when accessing a Swift array. The crashes always happen in methods triggered by user input or during menu item validation when I try to access the data source array by using the following code to determine the indexes of the relevant table rows: let indexes = clickedRow == -1 || selectedRowIndexes.contains(clickedRow) ? selectedRowIndexes : IndexSet(integer: clickedRow) I was never able to reproduce the crash until today. When the app crashed in the Xcode debugger, I examined the variables clickedRow and selectedRowIndexes.first, which were 1 and 0 respectively. What's interesting: the table view only contained one row, so clickedRow was effectively invalid. I tried to reproduce the issue several times afterwards, but it never happened again. What could cause this issue? What are the circumstances where it is invalid? Do I always have to explicitly check if clickedRow is within the data source range?
Topic: UI Frameworks SubTopic: AppKit Tags:
4
0
96
Apr ’25
NSToolbar doesn't restore displayMode when NSWindow.titleVisibility = .hidden
Apparently when setting a window to hide its title, the toolbar's displayMode is not restored when relaunching the app. For example, by default my app sets to show toolbar icons only, but when right-clicking it, selecting "Icon and Text" and relaunching the app, it's again "Icon Only". Is there a workaround? I've filed FB17144212. class ViewController: NSViewController, NSToolbarDelegate { override func viewDidAppear() { let toolbar = NSToolbar(identifier: "toolbar") toolbar.delegate = self toolbar.autosavesConfiguration = true toolbar.displayMode = .iconOnly view.window?.titleVisibility = .hidden view.window?.toolbar = toolbar view.window?.toolbarStyle = .unified } func toolbarAllowedItemIdentifiers(_ toolbar: NSToolbar) -> [NSToolbarItem.Identifier] { return [.init(rawValue: "item")] } func toolbarDefaultItemIdentifiers(_ toolbar: NSToolbar) -> [NSToolbarItem.Identifier] { return [.init(rawValue: "item")] } func toolbar(_ toolbar: NSToolbar, itemForItemIdentifier itemIdentifier: NSToolbarItem.Identifier, willBeInsertedIntoToolbar flag: Bool) -> NSToolbarItem? { let item = NSToolbarItem(itemIdentifier: itemIdentifier) item.image = NSImage(named: NSImage.addTemplateName)! item.label = "item" return item } }
Topic: UI Frameworks SubTopic: AppKit Tags:
2
0
79
Apr ’25
Get NSTextView selection frame with NSTextLayoutManager
I'm trying to update my app to use TextKit 2. The one thing that I'm still not sure about is how I can get the selection frame. My app uses it to auto-scroll the text to keep the cursor at the same height when the text wraps onto a new line or a newline is manually inserted. Currently I'm using NSLayoutManager.layoutManager!.boundingRect(forGlyphRange:in:). The code below almost works. When editing the text or changing the selection, the current selection frame is printed out. My expectation is that the selection frame after a text or selection change should be equal to the selection frame before the next text change. I've noticed that this is not always true when the text has a NSParagraphStyle with spacing > 0. As long as I type at the end of the text, everything's fine, but if I insert some lines, then move the selection somewhere into the middle of the text and insert another newline, the frame printed after manually moving the selection is different than the frame before the newline is inserted. It seems that the offset between the two frames is exactly the same as the paragraph style's spacing. Instead when moving the selection with the arrow key the printed frames are correct. I've filed FB17104954. class ViewController: NSViewController, NSTextViewDelegate { private var textView: NSTextView! override func loadView() { let scrollView = NSScrollView(frame: CGRect(x: 0, y: 0, width: 400, height: 400)) textView = NSTextView(frame: scrollView.frame) textView.autoresizingMask = [.width, .height] textView.delegate = self let paragraphStyle = NSMutableParagraphStyle() paragraphStyle.lineSpacing = 40 textView.typingAttributes = [.foregroundColor: NSColor.labelColor, .paragraphStyle: paragraphStyle] scrollView.documentView = textView scrollView.hasVerticalScroller = true view = scrollView } func textView(_ textView: NSTextView, shouldChangeTextIn affectedCharRange: NSRange, replacementString: String?) -> Bool { print("before", selectionFrame.maxY, selectionFrame) return true } func textDidChange(_ notification: Notification) { print("after ", selectionFrame.maxY, selectionFrame) } func textViewDidChangeSelection(_ notification: Notification) { print("select", selectionFrame.maxY, selectionFrame) } var selectionFrame: CGRect { guard let selection = textView.textLayoutManager!.textSelections.first?.textRanges.first else { return .null } var frame = CGRect.null textView.textLayoutManager!.ensureLayout(for: selection) textView.textLayoutManager!.enumerateTextSegments(in: selection, type: .selection, options: [.rangeNotRequired]) { _, rect, _, _ in frame = rect return false } return frame } }
0
1
118
Apr ’25
NSTextView.shouldDrawInsertionPoint doesn't work with TextKit 2
The following code only ever causes shouldDrawInsertionPoint to be printed (no drawInsertionPoint), but even if that method returns false, the blinking insertion point is still drawn. On the other hand, with TextKit 1 it works as expected. Is there a way to hide the default insertion point in TextKit 2? My app draws its own. I've filed FB13684251. class TextView: NSTextView { override var shouldDrawInsertionPoint: Bool { print("shouldDrawInsertionPoint") return false } override func drawInsertionPoint(in rect: NSRect, color: NSColor, turnedOn flag: Bool) { print("drawInsertionPoint", flag) } } ``
Topic: UI Frameworks SubTopic: AppKit Tags:
9
0
184
Apr ’25
Force NSDocument save panel to select most specific type in format popup button
My app supports different plain text file formats, including the standard .txt and Markdown. When creating a new document, my app already asks which format it should have, so when saving it, I would expect that the save panel already selects that format in the popup button, but currently it always selects "Plain Text". For example, I would expect for a Markdown document that it selects "Markdown" instead of "Plain Text". Is there a way to force it to select the most specific format matching the document format?
Topic: UI Frameworks SubTopic: AppKit Tags:
6
1
160
Apr ’25
Printing NSTextStorage over multiple UITextView produces weird results
I would like to print a NSTextStorage on multiple pages and add annotations to the side margins corresponding to certain text ranges. For example, for all occurrences of # at the start of a line, the side margin should show an automatically increasing number. My idea was to create a NSLayoutManager and dynamically add NSTextContainer instances to it until all text is laid out. The layoutManager would then allow me to get the bounding rectangle of the interesting text ranges so that I can draw the corresponding numbers at the same height inside the side margin. This approach works well on macOS, but I'm having some issues on iOS. When running the code below in an iPad Simulator, I would expect that the print preview shows 3 pages, the first with the numbers 0-1, the second with the numbers 2-3, and the last one with the number 4. Instead the first page shows the number 4, the second one the numbers 2-4, and the last one the numbers 0-4. It's as if the pages are inverted, and each page shows the text starting at the correct location but always ending at the end of the complete text (and not the range assigned to the relative textContainer). I've created FB17026419. class ViewController: UIViewController { override func viewDidAppear(_ animated: Bool) { let printController = UIPrintInteractionController.shared let printPageRenderer = PrintPageRenderer() printPageRenderer.pageSize = CGSize(width: 100, height: 100) printPageRenderer.textStorage = NSTextStorage(string: (0..<5).map({ "\($0)" }).joined(separator: "\n"), attributes: [.font: UIFont.systemFont(ofSize: 30)]) printController.printPageRenderer = printPageRenderer printController.present(animated: true) { _, _, error in if let error = error { print(error.localizedDescription) } } } } class PrintPageRenderer: UIPrintPageRenderer, NSLayoutManagerDelegate { var pageSize: CGSize! var textStorage: NSTextStorage! private let layoutManager = NSLayoutManager() private var textViews = [UITextView]() override var numberOfPages: Int { if !Thread.isMainThread { return DispatchQueue.main.sync { [self] in numberOfPages } } printFormatters = nil layoutManager.delegate = self textStorage.addLayoutManager(layoutManager) if textStorage.length > 0 { let glyphRange = layoutManager.glyphRange(forCharacterRange: NSRange(location: textStorage.length - 1, length: 0), actualCharacterRange: nil) layoutManager.textContainer(forGlyphAt: glyphRange.location, effectiveRange: nil) } var page = 0 for textView in textViews { let printFormatter = textView.viewPrintFormatter() addPrintFormatter(printFormatter, startingAtPageAt: page) page += printFormatter.pageCount } return page } func layoutManager(_ layoutManager: NSLayoutManager, didCompleteLayoutFor textContainer: NSTextContainer?, atEnd layoutFinishedFlag: Bool) { if textContainer == nil { addPage() } } private func addPage() { let textContainer = NSTextContainer(size: pageSize) layoutManager.addTextContainer(textContainer) let textView = UITextView(frame: CGRect(origin: .zero, size: pageSize), textContainer: textContainer) textViews.append(textView) } }
Topic: UI Frameworks SubTopic: UIKit Tags:
4
0
122
Mar ’25
NSView.knowsPageRange(_:) called twice when showing print panel
When creating a default macOS document-based Xcode project and using the code below (and wiring the File menu's Print item to printDocument: instead of the default print:, which does nothing), opening the print panel causes PrintView.knowsPageRange(_:) to be called twice. Is this a bug? My app populates PrintView dynamically, and for large documents it can be quite inefficient to populate it once, only for the contents to be immediately discarded and populated again. A workaround that came to my mind would be to check if the print options have changed, though I'm not sure if it's a reliable indicator that the print preview is effectively the same. I created FB17018494. class Document: NSDocument { override func makeWindowControllers() { addWindowController(NSStoryboard(name: NSStoryboard.Name("Main"), bundle: nil).instantiateController(withIdentifier: NSStoryboard.SceneIdentifier("Document Window Controller")) as! NSWindowController) } override func printOperation(withSettings printSettings: [NSPrintInfo.AttributeKey : Any]) throws -> NSPrintOperation { return NSPrintOperation(view: PrintView(frame: CGRect(x: 0, y: 0, width: 100, height: 100)), printInfo: NSPrintInfo(dictionary: printSettings)) } } class PrintView: NSView { override func knowsPageRange(_ range: NSRangePointer) -> Bool { print("knowsPageRange") range.pointee = NSRange(location: 1, length: 1) return true } }
Topic: UI Frameworks SubTopic: AppKit
1
0
67
Mar ’25
Crash when assigning NSImage to `@objc dynamic var` property
Xcode downloaded a crash report for my app which I don't quite understand. It seems the following line caused the crash: myEntity.image = newImage where myEntity is of type MyEntity: class MyEntity: NSObject, Identifiable { @objc dynamic var image: NSImage! ... } The code is called on the main thread. According to the crash report, thread 0 makes that assignment, and at the same time thread 16 is calling [NSImageView asynchronousPreparation:prepareResultUsingParameters:]. What could cause such a crash? Could I be doing something wrong or is this a bug in macOS? crash.crash
11
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235
Mar ’25