Construct and manage a graphical, event-driven user interface for your macOS app using AppKit.

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-applicationDockMenu: method on NSApplicationDelegate doesn't work when attached to debugger
When I add a simple menu to the dock via the NSApplicationDelegate method -applicationDockMenu: and run the app from Xcode it doesn't work. -(NSMenu*)applicationDockMenu:(NSApplication*)sender { NSMenu *dockMenu = [self buildDockMenu]; if (dockMenu != nil) { NSLog(@"Returning dock menu."); return dockMenu; } else { NSLog(@"Not ready to build dock menu"); return nil; } } When I run the app, my main app window shows up but nothing logs out in -applicationDockMenu: until I click outside my app's window (so if I click the desktop background, or a Finder window, or whatever). Then after I click outside my app's main window this logs out: Returning dock menu. The "Not ready to build dock menu" message does not log out. But...when I right click on the dock icon, the menu doesn't show up. But if I stop the app from Xcode and just run it not attached to the debugger, the dock menu does show up. But this makes the debugging/testing situation not ideal.
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NSOutlineView / NSTableView's Setting lineScroll to a somewhat absurd value of 304 in -tile
So I'm working on adding another component to my app that uses NSOutlineView, as we do in AppKit. There will probably always be less than 25 rows here. One row is much larger than the others. Not sure if any of this matters. What I know is I noticed scrolling it is very jank. It's going way too fast. So I took a peek and see lineScroll is getting is 304 in Interface Builder. Not sure how that happened. I changed it to like 24. Then Interface Builder automatically changes it back to 304. So in -viewDidLoad I just set it: NSScrollView *scrollView = self.outlineView.enclosingScrollView; scrollView.verticalLineScroll = 24.0; scrollView.lineScroll = 24.0; But scrolling still is busted. So I subclass NSScrollView and override the setters. For some reason, NSTableView's -tile method is deciding to change the lineScroll to 304, all on its own. So every time tile is called. line scrolls get reset to 304.
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AppKit - Legal to Change a View's Frame in -viewDidLayout?
I have (had) a view controller that does a bit of manual layout in a -viewDidLayout override. This was pretty easy to manage - however since introducing NSGlassEffectView into the view hierarchy I sometimes am getting hit with "Unable to simultaneously satisfy constraints" and Appkit would break a constraint to 'recover.' It appears translatesAutoresizingMaskIntoConstraints is creating some really weird fixed width and height constraints. Here I wasn't doing any autolayout - just add the glass view and set its frame in -viewDidLayout. At runtime since I do manual layout in -viewDidLayout the frames are fixed and there is no real "error" in my app in practice though I wanted to get rid of the constraint breaking warning being logged because I know Autolayout can be aggressive about 'correctness' who knows if they decide to throw and not catch in the future. In my perfect world I would probably just prefer a view.doesManualLayout = YES here - the subviews are big containers no labels so localization is not an issue for me. Rather than playing with autoresizing masks to get better translated constraints I decided to set translatesAutoresizingMaskIntoConstraints to NO and make the constraints myself. Now I get hit with the following exception: "The window has been marked as needing another Layout Window pass, but it has already had more Layout Window passes than there are views in the window" So this happens because the view which now has constraints -- I adjusted the frame of it one point in -viewDidLayout. My question is - is not legal to make changes in -viewDidLayout - which seems like the AppKit version of -viewDidLayoutSubviews. In UIKit I always thought it was fine to make changes in -viewDidLayoutSubviews to frames - even if constraints were used - this is a place where you could override things in complex layouts that cannot be easily described in constraints. But in AppKit if you touch certain frames in -viewDidLayout it can now cause this exception (also related: https://aninterestingwebsite.com/forums/thread/806471) I will change the constant of one of the constraints to account for the 1 point adjustment but my question still stands - is it not legal to touch frames in -viewDidLayout when autolayout constraints are used on that subview? It is (or at least was if I remember correctly) permitted to change the layout in -viewDidLayoutSubviews in UIKit but AppKit seems to be more aggressive in its checking for layout correctness). What about calling -sizeToFit on a control in viewDidLayout or some method that has side effect of invalidating layout in a non obvious way, is doing things like this now 'dangerous?' Shouldn't AppKit just block the layout from being invalidated from within -viewDidLayout - and leave whatever the layout is as is when viewDidLayout returns (thus making -viewDidLayout a useful place to override layout in the rare cases where you need a sledgehammer?)
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macOS 26: NSTokenField crashes due to NSGenericException caused by too many Update Constraints
This example application crashes when entering any text to the token field with FAULT: NSGenericException: The window has been marked as needing another Update Constraints in Window pass, but it has already had more Update Constraints in Window passes than there are views in the window. The app uses controlTextDidChange to update a live preview where it accesses the objectValue of the token field. If one character is entered, it also looks like the NSTokenFieldDelegate methods tokenField(_:styleForRepresentedObject:) tokenField(_:editingStringForRepresentedObject:) tokenField(_:representedObjectForEditing:) are called more than 10000 times until the example app crashes on macOS Tahoe 26 beta 6. I've reported this issue with beta 1 as FB18088608, but haven't heard back so far. I have multiple occurrences of this issue in my app, which is working fine on previous versions of macOS. I haven't found a workaround yet, and I’m getting anxious of this issue persisting into the official release.
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NSView uses NSLayoutConstraint, and the transform set on the layer gets reset when the window size changes.
import Cocoa class RedRotatedView: NSView { override func viewDidMoveToSuperview() { super.viewDidMoveToSuperview() DispatchQueue.main.async { self.applyRotation() } } private func applyRotation() { wantsLayer = true layer?.backgroundColor = NSColor.red.cgColor let radians = CGFloat(30 * Double.pi / 180.0) self.layer?.transform = CATransform3DMakeRotation(radians, 0, 0, 1) } override func layout() { super.layout() } } class MainView: NSView { let redView: RedRotatedView override init(frame frameRect: NSRect) { self.redView = RedRotatedView() super.init(frame: frameRect) setupRedView() } required init?(coder: NSCoder) { fatalError("init(coder:) has not been implemented") } private func setupRedView() { redView.wantsLayer = true redView.layer?.backgroundColor = NSColor.red.cgColor addSubview(redView) redView.translatesAutoresizingMaskIntoConstraints = false NSLayoutConstraint.activate([ redView.centerXAnchor.constraint(equalTo: centerXAnchor), redView.centerYAnchor.constraint(equalTo: centerYAnchor), redView.widthAnchor.constraint(equalToConstant: 200), redView.heightAnchor.constraint(equalToConstant: 200) ]) // redView.frame = NSRect(x:100,y:100,width: 200,height: 200) } } @main struct AppKitRotationTestApp { static func main() { let app = NSApplication.shared let delegate = AppDelegate() app.delegate = delegate app.run() } } class AppDelegate: NSObject, NSApplicationDelegate { var window: NSWindow! func applicationDidFinishLaunching(_ aNotification: Notification) { let mainView = MainView(frame: NSRect(x: 0, y: 0, width: 800, height: 600)) window = NSWindow( contentRect: NSRect(x: 0, y: 0, width: 800, height: 600), styleMask: [.titled, .closable, .resizable, .miniaturizable], backing: .buffered, defer: false ) window.center() window.title = "AppKit Rotation Test" window.contentView = mainView window.makeKeyAndOrderFront(nil) } func applicationWillTerminate(_ aNotification: Notification) { } func applicationSupportsSecureRestorableState(_ app: NSApplication) -> Bool { return true } } If NSLayoutConstraint is not used directly and the NSView's frame is set directly, this situation does not occur. How can I avoid the transform being reset when using NSLayoutConstraint for layout?
Topic: UI Frameworks SubTopic: AppKit
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NSWritingToolsCoordinator issue with text replacement
Hello, we are currently integrating Writing Tools into our macOS application using NSWritingToolsCoordinator with a custom NSView. Overall, the integration is going well and we are generally satisfied with the API. However, text replacement is sometimes not using NSWritingToolsCoordinator callback function. When selecting “Replace” from a preview in a Writing Tools UI popup, the text replacement is performed via the NSTextInputClient callback function (insertText:), which does not seem correct. This is especially problematic in multi-context scenarios, because NSTextInputClient insertText: does not provide the required information about the Writing tools context being used. As a result, it is not possible to determine which context is being modified when managing more than a single context. In our view, Writing Tools should consistently use the callback function of NSWritingToolsCoordinator for text replacement, whatever is the action performed. This is essential for properly handling multi-context use cases. This issue is reproducible with the sample app project provided here https://aninterestingwebsite.com/documentation/appkit/enhancing-your-custom-text-engine-with-writing-tools. If you define a breakpoint in function writingToolsCoordinator:replaceRange:inContext:proposedText:reason:animationParameters:completion: of the Writing tools coordinator, the function is not triggered if text replacement is performed from a preview like for "Summary" with "replace" button. NSWritingToolsCoordinator callback function seems to be called only when text replacement is performed directly inline (in the text view) without external preview so. i have opened a issue with feedback assistant: FB22401950. Best regards.
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NSWritingToolsCoordinator issue with text replacement
Hello, we are currently integrating Writing Tools into our macOS application using NSWritingToolsCoordinator with a custom NSView. Overall, the integration is going well and we are generally satisfied with the API. However, text replacement is sometimes not using NSWritingToolsCoordinator callback function. When selecting “Replace” from a preview in a Writing Tools UI popup, the text replacement is performed via the NSTextInputClient callback function (insertText:), which does not seem correct. This is especially problematic in multi-context scenarios, because NSTextInputClient insertText: does not provide the required information about the Writing tools context being used. As a result, it is not possible to determine which context is being modified when managing more than a single context. In our view, Writing Tools should consistently use the callback function of NSWritingToolsCoordinator for text replacement, whatever is the action performed. This is essential for properly handling multi-context use cases. This issue is reproducible with the sample app project provided here https://aninterestingwebsite.com/documentation/appkit/enhancing-your-custom-text-engine-with-writing-tools. If you define a breakpoint in function writingToolsCoordinator:replaceRange:inContext:proposedText:reason:animationParameters:completion: of the Writing tools coordinator, the function is not triggered if text replacement is performed from a preview like for "Summary" with "replace" button. NSWritingToolsCoordinator callback function seems to be called only when text replacement is performed directly inline (in the text view) without external preview so. i have opened a issue with feedback assistant: FB22401950. Best regards.
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Document Based App - NSDocumentController Opening the Wrong NSDocument/Window Controller on Tahoe 26.4
I have a Document based app. It supports different document types. One document type my app supports conforms to another document type that my app also supports. In my app these two UTIs are designated to open different NSDocument subclasses / window controllers. So say we have these two UTIs: com.DocumentType.SuperType com.DocumentType.SubType. Now I just noticed on Tahoe 26.4, the system is launching my app using NSDocument/window controller that is designated for com.DocumentType.SuperType, when I double click a file with the com.DocumentType.SubType UTI. I haven't changed the NSDocument configuration in many years but it looks like something changed recently.
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runModal exits with a fatal error.
I have been using this block of Swift code for weeks with no problems. Then, today, every time I invoke it it fails: let openPanel = NSOpenPanel() openPanel.canChooseFiles = true openPanel.allowsMultipleSelection = false openPanel.canChooseDirectories = true openPanel.canCreateDirectories = false openPanel.title = NSLocalizedString("Open a CSV file", comment: "Open a CSV File") var result = NSApplication.ModalResponse.OK do { try result = openPanel.runModal() } catch { print("Open Panel failed: \(error)") return } if result == .OK { CSVFile = openPanel.url!.path } else { openPanel.close() print("No CSV file selected.") return } I get this message pointing to the .openModal expression: "Thread 1: Fatal error: Unexpectedly found nil while unwrapping an Optional value" It's a real head-scratcher!
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NSTextAttachment.character symbol suddenly not available anymore resulting in compiler error
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?
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Layout recursion error message
Hi all, when I launch my macOS app from Xcode 16 on ARM64, appKit logs me this error on the debug console: It's not legal to call -layoutSubtreeIfNeeded on a view which is already being laid out. If you are implementing the view's -layout method, you can call -[super layout] instead. Break on _NSDetectedLayoutRecursion(void) to debug. This will be logged only once. This may break in the future. _NSDetectedLayoutRecursion doesn't help a lot, giving me these assembly codes from a call to a subclassed window method that looks like this: -(void) setFrame:(NSRect)frameRect display:(BOOL)flag { if (!_frameLocked) [super setFrame:frameRect display:flag]; } I have no direct call to -layoutSubtreeIfNeeded from a -layout implementation in my codes. I have a few calls to this method from update methods, however even if I comment all of them, the error is still logged... Finally, apart from that log, I cannot observe any layout error when running the program. So I wonder if this error can be safely ignored? Thanks!
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macOS Tahoe 26.3 - System Is Playing NSBeep At Inappropriate Times When Text Editing Ends Via -cancelOperation: (field editor)
When I end editing pressing the escape key, the system sometimes plays NSBeep(). I noticed this with NSBrowser. Every time I press escape to end editing the system beeps. At first I thought it was somewhere in my app but I set a symbolic breakpoint and discovered it was not coming from my code. I filed FB22127038. Since then I discovered that NSBeep playing at inappropriate times is not exclusive to NSBrowser. It appears if there is a NSTableView in the window and you just press the escape key (even if you aren't editing anything) AppKit beeps. It can be traced to: #0 0x0000000199e3184c in NSBeep () #1 0x000000019aa03fac in -[NSWindow doCommandBySelector:] () #2 0x000000019ac1d01c in -[NSTableView(NSTableViewViewBased) cancelOperation:] ()
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Password autofill not respecting contentType of NSSecureTextField
We have a Mac app the allows customers to create a user account in our system. However, we have found that on the 'create account' screen, the system's password autofill is popping up for the "New Password" field. We don't want this, because they need to enter a new password, not pull one from the Passwords app. I built a test project with a basic UI and explicitly set the content type to None in the XIB. However, I can see when I put focus on the "New Password" NSSecureTextField, the system shows the passwords autofill popup. How can I explicitly suppress this on a per text field basis? (We are developing on macOS 26.3 right now with Xcode 26.3)
Topic: UI Frameworks SubTopic: AppKit
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NSDocument "saveToURL:ofType:..." is using outdated file type
These days I've observed a strange behavior in my document-based app on macOS: Its NSDocument class implementation is overwriting "saveToURL:ofType:forSaveOperation:completionHandler:", performing some additional checks and calling super by passing the original parameters. As my app is supporting various file formats for writing (and exporting those UTIs) the user can open a file in one format and save it to another. NSDocument is calling the mentioned methods implicitly after completing the "Save as..." dialog. If this happens, the passed-on fileType is still the one of format #1, although the file is saved with the file name extension of format #2. This hick-up is not directly obvious to the user. But if the file is re-saved (e.g. after modifications), Cocoa is trying to extend the sandbox for the URL of type #1, and fails with the following error message at the Xcode console: -[STBDocument saveToURL:ofType:forSaveOperation:completionHandler:] [Line 521] typeName: com.janome.jef -[STBDocument saveToURL:ofType:forSaveOperation:completionHandler:] [Line 523] targetTypeUTI: com.tajima.dst NSFileSandboxingRequestRelatedItemExtension: Failed to issue extension for /Users/matthias/Desktop/Ohne Titel.jef because: Error Domain=NSPOSIXErrorDomain Code=3 "No such process" -[NSFileCoordinator itemAtURL:willMoveToURL:] could not get a sandbox extension. oldURL: file:///Users/matthias/Desktop/Ohne%20Titel.dst, newURL: file:///Users/matthias/Desktop/Ohne%20Titel.jef I'm currently fixing this issue by determining the UTType for the new file name extension and passing it to super. Unfortunately I have no idea how long this issue was already present, and cannot replicate it with a sample app based on Apple's Xcode 26 template (too many differences to my >15 years old app) - so I won't file a bug report. Take this post just for information in case someone else is facing a similar situation...
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PDFView left-anchors to window edge instead of centering between sidebar and inspector (macOS Tahoe)
I'm building a document viewer on macOS Tahoe with a 3-column NSSplitViewController (sidebar | detail | inspector), trying to replicate how Preview displays PDFs with the page centered in the visible gap between the panels, with content bleeding under them when panning or zooming. I'm using the approach from Build an AppKit app with the new design (WWDC25): detailItem.automaticallyAdjustsSafeAreaInsets = true safeAreaInsets reports the correct values (e.g. left: 208, right: 240), and the frame does extend under both panels. But PDFView with autoScales = true anchors the page to the left edge of the window instead of centering it in the visible gap between the sidebar and inspector. I can get the page to center correctly by constraining PDFView to view.safeAreaLayoutGuide, but then content no longer extends under the panels when panning or zooming, which defeats the whole purpose. What's the correct way to center PDFView content within the visible gap while keeping the frame full-width so content bleeds under the panels? I've attached pictures of how Preview does it.
Topic: UI Frameworks SubTopic: AppKit
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NSBrowser -deselectAll: broken on macOS Tahoe 26.4
So if I have a selection in NSBrowser. I hit Option+Command+A to invoke "Deselect" the selection in the parent for the last column drops its selections, as expected. But the column doesn't drop off the browser. The delegate method (void)browser:(NSBrowser *)browser didChangeLastColumn:(NSInteger)oldLastColumn toColumn:(NSInteger)column NS_SWIFT_UI_ACTOR; Never fires (since the column isn't dropped off). But we have. dangling last column with no selection in the previous column. Now if there's enough room for me to deselect by clicking the background, the last column drops off, as expected. This seems to be fairly new? Anyone else experiencing this? These 26point updates seem to keep punching me in the face. And yes. deselect all seems somewhat broken in Column view in the Finder as well, but in a seemingly different way. In Finder it just seems to change the selection color like it deactivated the window but doesn't drop the selection. For me, the selection IS dropped but the column remains visible. Maybe they are using Cocoa bindings or something that resyncs the selection after the mess up. I dk.
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NSWorkspace - macOS Tahoe 26.4 -activateFileViewerSelectingURLs: Crashes When Called Off The Main Thread
So I just installed the 26.4 update and unfortunately I have to debug this newly introduced issue (that may work its way into a separate thread). In my debugging steps I'm testing something related to files and I used -activateFileViewerSelectingURLs: to show the file in Finder. Now I am off the main thread. I added this line for testing purposes and I get a crash: NSWindow should only be instantiated on the main thread!' terminating due to uncaught exception of type NSException. So apparently - NSWorkspace is calling through to NSServices APIs and for some reason the system wants to present an NSError, which is a subtopic and other bug on its own because the 'Show in Finder" functionality actually WORKS but it crashed my app! #22in +[NSAlert alertWithError:] () #23in -[NSApplication(NSErrorPresentation) presentError:] () #24 +[NSServicesMenuHandler _performServiceFromEntry:withPasteboard:withRequestor:withInvocationSourceType:withCarbonFocus:withSendTypes:withReturnTypes:canReleasePasteboardImmediately:] () #25 +[NSServicesMenuHandler _performServiceWithoutAlternatesFromEntry:withPasteboard:withRequestor:withInvocationSourceType:] () #26 +[NSServicesMenuHandler _performServiceFromEntry:withPasteboard:withRequestor:withInvocationSourceType:] () #27 [NSWorkspace activateFileViewerSelectingURLs:] What error it is trying to present.. I have no idea. I'm not sure if I actually have a code path that calls this method off the main thread but I guess I'll have to check. This clearly goes against the documentation. NSWorkspace documentation clearly states: -activateFileViewerSelectingURLs: Discussion You can safely call this method from any thread of your app. Is this new in 26.4? I'm not sure but I just noticed. I definitely use other NSWorkspace methods off the main thread in areas of my app. Like -activateFileViewerSelectingURLs: the documentation for those other methods claims you can safely call them off the main thread. So now I'm concerned.
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NSPathControl Causing Disk I/O Reading NSURL Resource Values On the Main Thread
Sort of a continuation of - https://aninterestingwebsite.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.
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-applicationDockMenu: method on NSApplicationDelegate doesn't work when attached to debugger
When I add a simple menu to the dock via the NSApplicationDelegate method -applicationDockMenu: and run the app from Xcode it doesn't work. -(NSMenu*)applicationDockMenu:(NSApplication*)sender { NSMenu *dockMenu = [self buildDockMenu]; if (dockMenu != nil) { NSLog(@"Returning dock menu."); return dockMenu; } else { NSLog(@"Not ready to build dock menu"); return nil; } } When I run the app, my main app window shows up but nothing logs out in -applicationDockMenu: until I click outside my app's window (so if I click the desktop background, or a Finder window, or whatever). Then after I click outside my app's main window this logs out: Returning dock menu. The "Not ready to build dock menu" message does not log out. But...when I right click on the dock icon, the menu doesn't show up. But if I stop the app from Xcode and just run it not attached to the debugger, the dock menu does show up. But this makes the debugging/testing situation not ideal.
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NSOutlineView / NSTableView's Setting lineScroll to a somewhat absurd value of 304 in -tile
So I'm working on adding another component to my app that uses NSOutlineView, as we do in AppKit. There will probably always be less than 25 rows here. One row is much larger than the others. Not sure if any of this matters. What I know is I noticed scrolling it is very jank. It's going way too fast. So I took a peek and see lineScroll is getting is 304 in Interface Builder. Not sure how that happened. I changed it to like 24. Then Interface Builder automatically changes it back to 304. So in -viewDidLoad I just set it: NSScrollView *scrollView = self.outlineView.enclosingScrollView; scrollView.verticalLineScroll = 24.0; scrollView.lineScroll = 24.0; But scrolling still is busted. So I subclass NSScrollView and override the setters. For some reason, NSTableView's -tile method is deciding to change the lineScroll to 304, all on its own. So every time tile is called. line scrolls get reset to 304.
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AppKit - Legal to Change a View's Frame in -viewDidLayout?
I have (had) a view controller that does a bit of manual layout in a -viewDidLayout override. This was pretty easy to manage - however since introducing NSGlassEffectView into the view hierarchy I sometimes am getting hit with "Unable to simultaneously satisfy constraints" and Appkit would break a constraint to 'recover.' It appears translatesAutoresizingMaskIntoConstraints is creating some really weird fixed width and height constraints. Here I wasn't doing any autolayout - just add the glass view and set its frame in -viewDidLayout. At runtime since I do manual layout in -viewDidLayout the frames are fixed and there is no real "error" in my app in practice though I wanted to get rid of the constraint breaking warning being logged because I know Autolayout can be aggressive about 'correctness' who knows if they decide to throw and not catch in the future. In my perfect world I would probably just prefer a view.doesManualLayout = YES here - the subviews are big containers no labels so localization is not an issue for me. Rather than playing with autoresizing masks to get better translated constraints I decided to set translatesAutoresizingMaskIntoConstraints to NO and make the constraints myself. Now I get hit with the following exception: "The window has been marked as needing another Layout Window pass, but it has already had more Layout Window passes than there are views in the window" So this happens because the view which now has constraints -- I adjusted the frame of it one point in -viewDidLayout. My question is - is not legal to make changes in -viewDidLayout - which seems like the AppKit version of -viewDidLayoutSubviews. In UIKit I always thought it was fine to make changes in -viewDidLayoutSubviews to frames - even if constraints were used - this is a place where you could override things in complex layouts that cannot be easily described in constraints. But in AppKit if you touch certain frames in -viewDidLayout it can now cause this exception (also related: https://aninterestingwebsite.com/forums/thread/806471) I will change the constant of one of the constraints to account for the 1 point adjustment but my question still stands - is it not legal to touch frames in -viewDidLayout when autolayout constraints are used on that subview? It is (or at least was if I remember correctly) permitted to change the layout in -viewDidLayoutSubviews in UIKit but AppKit seems to be more aggressive in its checking for layout correctness). What about calling -sizeToFit on a control in viewDidLayout or some method that has side effect of invalidating layout in a non obvious way, is doing things like this now 'dangerous?' Shouldn't AppKit just block the layout from being invalidated from within -viewDidLayout - and leave whatever the layout is as is when viewDidLayout returns (thus making -viewDidLayout a useful place to override layout in the rare cases where you need a sledgehammer?)
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macOS 26: NSTokenField crashes due to NSGenericException caused by too many Update Constraints
This example application crashes when entering any text to the token field with FAULT: NSGenericException: The window has been marked as needing another Update Constraints in Window pass, but it has already had more Update Constraints in Window passes than there are views in the window. The app uses controlTextDidChange to update a live preview where it accesses the objectValue of the token field. If one character is entered, it also looks like the NSTokenFieldDelegate methods tokenField(_:styleForRepresentedObject:) tokenField(_:editingStringForRepresentedObject:) tokenField(_:representedObjectForEditing:) are called more than 10000 times until the example app crashes on macOS Tahoe 26 beta 6. I've reported this issue with beta 1 as FB18088608, but haven't heard back so far. I have multiple occurrences of this issue in my app, which is working fine on previous versions of macOS. I haven't found a workaround yet, and I’m getting anxious of this issue persisting into the official release.
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NSView uses NSLayoutConstraint, and the transform set on the layer gets reset when the window size changes.
import Cocoa class RedRotatedView: NSView { override func viewDidMoveToSuperview() { super.viewDidMoveToSuperview() DispatchQueue.main.async { self.applyRotation() } } private func applyRotation() { wantsLayer = true layer?.backgroundColor = NSColor.red.cgColor let radians = CGFloat(30 * Double.pi / 180.0) self.layer?.transform = CATransform3DMakeRotation(radians, 0, 0, 1) } override func layout() { super.layout() } } class MainView: NSView { let redView: RedRotatedView override init(frame frameRect: NSRect) { self.redView = RedRotatedView() super.init(frame: frameRect) setupRedView() } required init?(coder: NSCoder) { fatalError("init(coder:) has not been implemented") } private func setupRedView() { redView.wantsLayer = true redView.layer?.backgroundColor = NSColor.red.cgColor addSubview(redView) redView.translatesAutoresizingMaskIntoConstraints = false NSLayoutConstraint.activate([ redView.centerXAnchor.constraint(equalTo: centerXAnchor), redView.centerYAnchor.constraint(equalTo: centerYAnchor), redView.widthAnchor.constraint(equalToConstant: 200), redView.heightAnchor.constraint(equalToConstant: 200) ]) // redView.frame = NSRect(x:100,y:100,width: 200,height: 200) } } @main struct AppKitRotationTestApp { static func main() { let app = NSApplication.shared let delegate = AppDelegate() app.delegate = delegate app.run() } } class AppDelegate: NSObject, NSApplicationDelegate { var window: NSWindow! func applicationDidFinishLaunching(_ aNotification: Notification) { let mainView = MainView(frame: NSRect(x: 0, y: 0, width: 800, height: 600)) window = NSWindow( contentRect: NSRect(x: 0, y: 0, width: 800, height: 600), styleMask: [.titled, .closable, .resizable, .miniaturizable], backing: .buffered, defer: false ) window.center() window.title = "AppKit Rotation Test" window.contentView = mainView window.makeKeyAndOrderFront(nil) } func applicationWillTerminate(_ aNotification: Notification) { } func applicationSupportsSecureRestorableState(_ app: NSApplication) -> Bool { return true } } If NSLayoutConstraint is not used directly and the NSView's frame is set directly, this situation does not occur. How can I avoid the transform being reset when using NSLayoutConstraint for layout?
Topic: UI Frameworks SubTopic: AppKit
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How to let Appkit Scrollview get under sidebar or inspctor?
If I use a SwiftUI Scrollview and scroll horizontally, for example, the scroll content goes underneath the inspector or sidebar views on macOS 26 (probably on older versions as well) But by default, the AppKit scrollviews don't exhibit this behaviour. How do I adapt this to match SwiftUI behavior?
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2w
NSWritingToolsCoordinator issue with text replacement
Hello, we are currently integrating Writing Tools into our macOS application using NSWritingToolsCoordinator with a custom NSView. Overall, the integration is going well and we are generally satisfied with the API. However, text replacement is sometimes not using NSWritingToolsCoordinator callback function. When selecting “Replace” from a preview in a Writing Tools UI popup, the text replacement is performed via the NSTextInputClient callback function (insertText:), which does not seem correct. This is especially problematic in multi-context scenarios, because NSTextInputClient insertText: does not provide the required information about the Writing tools context being used. As a result, it is not possible to determine which context is being modified when managing more than a single context. In our view, Writing Tools should consistently use the callback function of NSWritingToolsCoordinator for text replacement, whatever is the action performed. This is essential for properly handling multi-context use cases. This issue is reproducible with the sample app project provided here https://aninterestingwebsite.com/documentation/appkit/enhancing-your-custom-text-engine-with-writing-tools. If you define a breakpoint in function writingToolsCoordinator:replaceRange:inContext:proposedText:reason:animationParameters:completion: of the Writing tools coordinator, the function is not triggered if text replacement is performed from a preview like for "Summary" with "replace" button. NSWritingToolsCoordinator callback function seems to be called only when text replacement is performed directly inline (in the text view) without external preview so. i have opened a issue with feedback assistant: FB22401950. Best regards.
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NSWritingToolsCoordinator issue with text replacement
Hello, we are currently integrating Writing Tools into our macOS application using NSWritingToolsCoordinator with a custom NSView. Overall, the integration is going well and we are generally satisfied with the API. However, text replacement is sometimes not using NSWritingToolsCoordinator callback function. When selecting “Replace” from a preview in a Writing Tools UI popup, the text replacement is performed via the NSTextInputClient callback function (insertText:), which does not seem correct. This is especially problematic in multi-context scenarios, because NSTextInputClient insertText: does not provide the required information about the Writing tools context being used. As a result, it is not possible to determine which context is being modified when managing more than a single context. In our view, Writing Tools should consistently use the callback function of NSWritingToolsCoordinator for text replacement, whatever is the action performed. This is essential for properly handling multi-context use cases. This issue is reproducible with the sample app project provided here https://aninterestingwebsite.com/documentation/appkit/enhancing-your-custom-text-engine-with-writing-tools. If you define a breakpoint in function writingToolsCoordinator:replaceRange:inContext:proposedText:reason:animationParameters:completion: of the Writing tools coordinator, the function is not triggered if text replacement is performed from a preview like for "Summary" with "replace" button. NSWritingToolsCoordinator callback function seems to be called only when text replacement is performed directly inline (in the text view) without external preview so. i have opened a issue with feedback assistant: FB22401950. Best regards.
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Document Based App - NSDocumentController Opening the Wrong NSDocument/Window Controller on Tahoe 26.4
I have a Document based app. It supports different document types. One document type my app supports conforms to another document type that my app also supports. In my app these two UTIs are designated to open different NSDocument subclasses / window controllers. So say we have these two UTIs: com.DocumentType.SuperType com.DocumentType.SubType. Now I just noticed on Tahoe 26.4, the system is launching my app using NSDocument/window controller that is designated for com.DocumentType.SuperType, when I double click a file with the com.DocumentType.SubType UTI. I haven't changed the NSDocument configuration in many years but it looks like something changed recently.
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runModal exits with a fatal error.
I have been using this block of Swift code for weeks with no problems. Then, today, every time I invoke it it fails: let openPanel = NSOpenPanel() openPanel.canChooseFiles = true openPanel.allowsMultipleSelection = false openPanel.canChooseDirectories = true openPanel.canCreateDirectories = false openPanel.title = NSLocalizedString("Open a CSV file", comment: "Open a CSV File") var result = NSApplication.ModalResponse.OK do { try result = openPanel.runModal() } catch { print("Open Panel failed: \(error)") return } if result == .OK { CSVFile = openPanel.url!.path } else { openPanel.close() print("No CSV file selected.") return } I get this message pointing to the .openModal expression: "Thread 1: Fatal error: Unexpectedly found nil while unwrapping an Optional value" It's a real head-scratcher!
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NSTextAttachment.character symbol suddenly not available anymore resulting in compiler error
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?
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2w
Layout recursion error message
Hi all, when I launch my macOS app from Xcode 16 on ARM64, appKit logs me this error on the debug console: It's not legal to call -layoutSubtreeIfNeeded on a view which is already being laid out. If you are implementing the view's -layout method, you can call -[super layout] instead. Break on _NSDetectedLayoutRecursion(void) to debug. This will be logged only once. This may break in the future. _NSDetectedLayoutRecursion doesn't help a lot, giving me these assembly codes from a call to a subclassed window method that looks like this: -(void) setFrame:(NSRect)frameRect display:(BOOL)flag { if (!_frameLocked) [super setFrame:frameRect display:flag]; } I have no direct call to -layoutSubtreeIfNeeded from a -layout implementation in my codes. I have a few calls to this method from update methods, however even if I comment all of them, the error is still logged... Finally, apart from that log, I cannot observe any layout error when running the program. So I wonder if this error can be safely ignored? Thanks!
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macOS Tahoe 26.3 - System Is Playing NSBeep At Inappropriate Times When Text Editing Ends Via -cancelOperation: (field editor)
When I end editing pressing the escape key, the system sometimes plays NSBeep(). I noticed this with NSBrowser. Every time I press escape to end editing the system beeps. At first I thought it was somewhere in my app but I set a symbolic breakpoint and discovered it was not coming from my code. I filed FB22127038. Since then I discovered that NSBeep playing at inappropriate times is not exclusive to NSBrowser. It appears if there is a NSTableView in the window and you just press the escape key (even if you aren't editing anything) AppKit beeps. It can be traced to: #0 0x0000000199e3184c in NSBeep () #1 0x000000019aa03fac in -[NSWindow doCommandBySelector:] () #2 0x000000019ac1d01c in -[NSTableView(NSTableViewViewBased) cancelOperation:] ()
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3w
Password autofill not respecting contentType of NSSecureTextField
We have a Mac app the allows customers to create a user account in our system. However, we have found that on the 'create account' screen, the system's password autofill is popping up for the "New Password" field. We don't want this, because they need to enter a new password, not pull one from the Passwords app. I built a test project with a basic UI and explicitly set the content type to None in the XIB. However, I can see when I put focus on the "New Password" NSSecureTextField, the system shows the passwords autofill popup. How can I explicitly suppress this on a per text field basis? (We are developing on macOS 26.3 right now with Xcode 26.3)
Topic: UI Frameworks SubTopic: AppKit
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NSDocument "saveToURL:ofType:..." is using outdated file type
These days I've observed a strange behavior in my document-based app on macOS: Its NSDocument class implementation is overwriting "saveToURL:ofType:forSaveOperation:completionHandler:", performing some additional checks and calling super by passing the original parameters. As my app is supporting various file formats for writing (and exporting those UTIs) the user can open a file in one format and save it to another. NSDocument is calling the mentioned methods implicitly after completing the "Save as..." dialog. If this happens, the passed-on fileType is still the one of format #1, although the file is saved with the file name extension of format #2. This hick-up is not directly obvious to the user. But if the file is re-saved (e.g. after modifications), Cocoa is trying to extend the sandbox for the URL of type #1, and fails with the following error message at the Xcode console: -[STBDocument saveToURL:ofType:forSaveOperation:completionHandler:] [Line 521] typeName: com.janome.jef -[STBDocument saveToURL:ofType:forSaveOperation:completionHandler:] [Line 523] targetTypeUTI: com.tajima.dst NSFileSandboxingRequestRelatedItemExtension: Failed to issue extension for /Users/matthias/Desktop/Ohne Titel.jef because: Error Domain=NSPOSIXErrorDomain Code=3 "No such process" -[NSFileCoordinator itemAtURL:willMoveToURL:] could not get a sandbox extension. oldURL: file:///Users/matthias/Desktop/Ohne%20Titel.dst, newURL: file:///Users/matthias/Desktop/Ohne%20Titel.jef I'm currently fixing this issue by determining the UTType for the new file name extension and passing it to super. Unfortunately I have no idea how long this issue was already present, and cannot replicate it with a sample app based on Apple's Xcode 26 template (too many differences to my >15 years old app) - so I won't file a bug report. Take this post just for information in case someone else is facing a similar situation...
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PDFView left-anchors to window edge instead of centering between sidebar and inspector (macOS Tahoe)
I'm building a document viewer on macOS Tahoe with a 3-column NSSplitViewController (sidebar | detail | inspector), trying to replicate how Preview displays PDFs with the page centered in the visible gap between the panels, with content bleeding under them when panning or zooming. I'm using the approach from Build an AppKit app with the new design (WWDC25): detailItem.automaticallyAdjustsSafeAreaInsets = true safeAreaInsets reports the correct values (e.g. left: 208, right: 240), and the frame does extend under both panels. But PDFView with autoScales = true anchors the page to the left edge of the window instead of centering it in the visible gap between the sidebar and inspector. I can get the page to center correctly by constraining PDFView to view.safeAreaLayoutGuide, but then content no longer extends under the panels when panning or zooming, which defeats the whole purpose. What's the correct way to center PDFView content within the visible gap while keeping the frame full-width so content bleeds under the panels? I've attached pictures of how Preview does it.
Topic: UI Frameworks SubTopic: AppKit
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NSBrowser -deselectAll: broken on macOS Tahoe 26.4
So if I have a selection in NSBrowser. I hit Option+Command+A to invoke "Deselect" the selection in the parent for the last column drops its selections, as expected. But the column doesn't drop off the browser. The delegate method (void)browser:(NSBrowser *)browser didChangeLastColumn:(NSInteger)oldLastColumn toColumn:(NSInteger)column NS_SWIFT_UI_ACTOR; Never fires (since the column isn't dropped off). But we have. dangling last column with no selection in the previous column. Now if there's enough room for me to deselect by clicking the background, the last column drops off, as expected. This seems to be fairly new? Anyone else experiencing this? These 26point updates seem to keep punching me in the face. And yes. deselect all seems somewhat broken in Column view in the Finder as well, but in a seemingly different way. In Finder it just seems to change the selection color like it deactivated the window but doesn't drop the selection. For me, the selection IS dropped but the column remains visible. Maybe they are using Cocoa bindings or something that resyncs the selection after the mess up. I dk.
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QLThumbnailGenerator macOS 26.4 No Longer Honors Users 'Folder Color' Preference When Making Icons for Folders
I use QLThumbnailGenerator to generate icons. After updating to macOS Tahoe 26.4 the folder color preference of the user is no longer respected. It just makes the icon default 'light blue.'
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Mar ’26
NSWorkspace - macOS Tahoe 26.4 -activateFileViewerSelectingURLs: Crashes When Called Off The Main Thread
So I just installed the 26.4 update and unfortunately I have to debug this newly introduced issue (that may work its way into a separate thread). In my debugging steps I'm testing something related to files and I used -activateFileViewerSelectingURLs: to show the file in Finder. Now I am off the main thread. I added this line for testing purposes and I get a crash: NSWindow should only be instantiated on the main thread!' terminating due to uncaught exception of type NSException. So apparently - NSWorkspace is calling through to NSServices APIs and for some reason the system wants to present an NSError, which is a subtopic and other bug on its own because the 'Show in Finder" functionality actually WORKS but it crashed my app! #22in +[NSAlert alertWithError:] () #23in -[NSApplication(NSErrorPresentation) presentError:] () #24 +[NSServicesMenuHandler _performServiceFromEntry:withPasteboard:withRequestor:withInvocationSourceType:withCarbonFocus:withSendTypes:withReturnTypes:canReleasePasteboardImmediately:] () #25 +[NSServicesMenuHandler _performServiceWithoutAlternatesFromEntry:withPasteboard:withRequestor:withInvocationSourceType:] () #26 +[NSServicesMenuHandler _performServiceFromEntry:withPasteboard:withRequestor:withInvocationSourceType:] () #27 [NSWorkspace activateFileViewerSelectingURLs:] What error it is trying to present.. I have no idea. I'm not sure if I actually have a code path that calls this method off the main thread but I guess I'll have to check. This clearly goes against the documentation. NSWorkspace documentation clearly states: -activateFileViewerSelectingURLs: Discussion You can safely call this method from any thread of your app. Is this new in 26.4? I'm not sure but I just noticed. I definitely use other NSWorkspace methods off the main thread in areas of my app. Like -activateFileViewerSelectingURLs: the documentation for those other methods claims you can safely call them off the main thread. So now I'm concerned.
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Mar ’26
NSPathControl Causing Disk I/O Reading NSURL Resource Values On the Main Thread
Sort of a continuation of - https://aninterestingwebsite.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.
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Mar ’26