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

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SwiftUI crash on OSX 26 using NSColorPanel
Crashlog-0916-071225.log I have an app that crashes on OSX 26 only. I have a @StateObject which is an observer of the NSColorPanel. When I call let panel = NSColorPanel.shared in init(), SwiftUI will crash - apparently with an update while view is being updated. See crash log. I was able to work around it by adding let _ = NSColorPanel.shared in my AppDelegate before SwiftUI is initialized. The exact code worked fine in all previous OSX versions.
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98
Sep ’25
How to differentiate between user-generated NSEvents and programmatically posted events in AppKit?
Hi all, In my AppKit app, I sometimes simulate events programmatically, for example: func simulateKeyPress(characters: String, keyCode: UInt16) { guard let keyDown = NSEvent.keyEvent( with: .keyDown, location: .zero, modifierFlags: [], timestamp: 0, windowNumber: NSApp.mainWindow?.windowNumber ?? 0, context: nil, characters: characters, charactersIgnoringModifiers: characters, isARepeat: false, keyCode: keyCode ) else { return } NSApp.postEvent(keyDown, atStart: false) } At the same time, I install a local event monitor: NSEvent.addLocalMonitorForEvents(matching: .any) { event in // Ideally, detect whether this event came from a real user // (mouse, keyboard, trackpad, etc.) // or was programmatically generated via NSEvent + postEvent. return event } The problem: Events I generate with NSEvent.* factory methods and post using NSApp.postEvent look the same as real system events when received in the monitor. My question: Is there a supported way to tell whether an incoming NSEvent is system/user-generated vs programmatically posted?
Topic: UI Frameworks SubTopic: AppKit Tags:
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Sep ’25
macOS Document-Based SwiftUI App: “Save” menu item not localized in French
Hi everyone, I’ve run into a strange localization issue with macOS document-based apps in SwiftUI/AppKit. I created a standard document-based macOS app in Xcode (SwiftUI template) and added a French localization to the project. All system-generated menu bar commands (File → New, Close, Print, etc.) are correctly translated into French… except for “Save”, which remains in English. To rule out problems in my own code, I created a fresh, unmodified document-based app project in Xcode, and immediately added French localization without touching any code. Same result: all commands are translated except “Save”. This suggests the issue isn’t specific to my app code, but either the project template, or possibly macOS itself. My environment • Xcode version: 16.4 • macOS version: 15.6.1 Sequoia] • Swift: Swift 6 Questions 1. Has anyone else seen this issue with the “Save” command not being localized? 2. Is this expected behavior (maybe “Save” is handled differently from other menu items)? 3. If it’s a bug in the template or OS, is there a known workaround? Thanks for any insights P.S. Please note that I'm a total beginner
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192
Sep ’25
Inset or disable NSSheetEffectDimmingView when presenting a sheet?
I have an NSWindow that isn't entirely opaque. When presenting a sheet AppKit overlays the window with NSSheetEffectDimmingView. The problem is the entire window frame is used so NSSheetEffectDimmingView overlays the transparent areas of the window and it looks bad. Is there a clean way to inset NSSheetEffectDimmingView or even perhaps disable this behavior completely so I can draw my own? I'm looking for a clean solution (other than modifying the view hierarchy of NSNextStepFrame) or swizzles which I might have to resort to if there is no other way.
Topic: UI Frameworks SubTopic: AppKit Tags:
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123
Sep ’25
NSWindowCollectionBehavior in Full Screen Spaces
The NSWindow collection behavior is supposed to allow for a window to appear in all spaces, even when another window is full screen in that space. However, I cannot get this to work as expected with any combination. This should be as simple as: window.level = .screenSaver window.collectionBehavior = [ .canJoinAllSpaces, .fullScreenAuxiliary, .canJoinAllApplications, .stationary, .ignoresCycle ] If I have a window (Safari for example) which is full screen in its own space, run my app and change to the Safari window's space, my app's window is not visible at all; it will only float on top of windows in non-fullscreen spaces. What am I misunderstanding?
Topic: UI Frameworks SubTopic: AppKit Tags:
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117
Sep ’25
NSToolbar Space item rendered with Liquid Glass Background
Hi, I have a NSToolbar in my Mac Catalyst app with a space and flexible space item in it (https://developer.apple.com/documentation/appkit/nstoolbaritem/identifier/space). On macOS Tahoe the space item is being rendered with a Liquid Glass effect and seems to be automatically grouped with the previous item. Is there a way to prevent this? It basically adds some undesired padding next to the previous item and looks add. The flexible space is rendered normally and as before. I am talking about the space right next to the back chevron item. Thanks for any hints!
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Sep ’25
Printing of NSTextView
I have a document-based macOS app written in Objective-C, and each document window contains a scrollable NSTextView. I know that printing can get complicated if you want to do nice pagination, but is there a quick and dirty way to get basic printing working? As it is, the print panel shows up, but its preview area is totally blank. Here's the current printing part of my NSDocument subclass. - (NSPrintInfo *)printInfo { NSPrintInfo *printInfo = [super printInfo]; [printInfo setHorizontalPagination: NSPrintingPaginationModeFit]; [printInfo setHorizontallyCentered: NO]; [printInfo setVerticallyCentered: NO]; [printInfo setLeftMargin: 72.0]; [printInfo setRightMargin: 72.0]; [printInfo setTopMargin: 72.0]; [printInfo setBottomMargin: 72.0]; return printInfo; } - (void)printDocumentWithSettings:(NSDictionary<NSPrintInfoAttributeKey, id> *)printSettings showPrintPanel:(BOOL)showPrintPanel delegate:(id)delegate didPrintSelector:(SEL)didPrintSelector contextInfo:(void *)contextInfo { NSPrintInfo* thePrintInfo = [self printInfo]; [thePrintInfo setVerticallyCentered: NO ]; NSPrintOperation *op = [NSPrintOperation printOperationWithView: _textView printInfo: thePrintInfo ]; [op runOperationModalForWindow: _docWindow delegate: delegate didRunSelector: didPrintSelector contextInfo: contextInfo]; }
Topic: UI Frameworks SubTopic: AppKit Tags:
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Aug ’25
Why is the nib still loaded even though the class has been registered with NSCollectionView?
I implemented a subclass of NSCollectionViewItem: class ViewItem: NSCollectionViewItem { override func loadView() { self.view = NSView() } } and registed to NSCollectionView: class PictureFrameThemeListView: NSCollectionView { init(viewModel: PictureFrameViewModel) { super.init(frame: .zero) self.register(ViewItem.self, forItemWithIdentifier: .item) } However, when calling makeItem(withIdentifier:for:), the following error is prompted: FAULT: NSInternalInconsistencyException: -[NSNib _initWithNibNamed:bundle:options:] could not load the nib 'Item' in bundle NSBundle What confuses me is that I registered the subclass of NSCollectionViewItem, why do NSCollectionView to init the NSNib?
Topic: UI Frameworks SubTopic: AppKit Tags:
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Aug ’25
Xcode unit test "Creating more than one Application"
When I try to make a unit test target for my macOS app that uses Objective-C, running tests fails, and the debugging log shows a message "Creating more than one Application". If, on the other hand, when I create the unit test target, I select "None" as the target to be tested, and then add all my sources to that target, my tests work. So, I can get my testing done, but I think I must be doing something wrong. By the way, along with the error message, there is a stack crawl: 0 CoreFoundation 0x00007ff8140410aa __exceptionPreprocess + 242 1 libobjc.A.dylib 0x00007ff813b660b7 objc_exception_throw + 48 2 Foundation 0x00007ff814f19bd8 -[NSCalendarDate initWithCoder:] + 0 3 AppKit 0x00007ff817030062 -[NSApplication init] + 1718 4 XCTestCore 0x000000010774b0df -[XCTestDriver _createTestBundlePrincipalClassInstance] + 82 5 XCTestCore 0x0000000107749338 -[XCTestDriver _runTests] + 111 6 XCTestCore 0x000000010770f194 _XCTestMain + 126 7 libXCTestBundleInject.dylib 0x0000000106e8982d __copy_helper_block_e8_32s + 0 8 CoreFoundation 0x00007ff813fc9a91 __CFRUNLOOP_IS_CALLING_OUT_TO_A_BLOCK__ + 12 9 CoreFoundation 0x00007ff813fc99ca __CFRunLoopDoBlocks + 398 10 CoreFoundation 0x00007ff813fc883d __CFRunLoopRun + 898 11 CoreFoundation 0x00007ff813fc7e51 CFRunLoopRunSpecific + 560 12 HIToolbox 0x00007ff81da52f3d RunCurrentEventLoopInMode + 292 13 HIToolbox 0x00007ff81da52b84 ReceiveNextEventCommon + 199 14 HIToolbox 0x00007ff81da52aa8 _BlockUntilNextEventMatchingListInModeWithFilter + 64 15 AppKit 0x00007ff8170689d8 _DPSNextEvent + 858 16 AppKit 0x00007ff817067882 -[NSApplication(NSEvent) _nextEventMatchingEventMask:untilDate:inMode:dequeue:] + 1214 17 AppKit 0x00007ff817059ef7 -[NSApplication run] + 586 18 AppKit 0x00007ff81702e111 NSApplicationMain + 817 19 PlainCalc 0x00000001057d0a91 main + 65 20 dyld 0x00007ff813b93418 start + 1896
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Aug ’25
NSTableView.reloadData(forRowIndexes:columnIndexes:) causes wrong subview layout when usesAutomaticRowHeights = true
I have a table view where each row has two labels, one left-aligned and one right-aligned. I would like to reload a single row, but doing so causes the right-aligned label to hug the left-aligned label. Before the reload: After the reload: Reloading the whole table view instead, or disabling automatic row height, solves the issue. Can a single row be reloaded without resorting to these two workarounds? I created FB13534100 1.5 years ago but got no response. class ViewController: NSViewController, NSTableViewDataSource, NSTableViewDelegate { override func loadView() { let tableView = NSTableView() tableView.translatesAutoresizingMaskIntoConstraints = false tableView.dataSource = self tableView.delegate = self tableView.usesAutomaticRowHeights = true let column = NSTableColumn() column.width = 400 tableView.addTableColumn(column) let scrollView = NSScrollView(frame: CGRect(x: 0, y: 0, width: 500, height: 500)) scrollView.translatesAutoresizingMaskIntoConstraints = false scrollView.documentView = tableView view = scrollView Timer.scheduledTimer(withTimeInterval: 2, repeats: false) { _ in print("reload") tableView.reloadData(forRowIndexes: IndexSet(integer: 2), columnIndexes: IndexSet(integer: 0)) // tableView.reloadData() } } func numberOfRows(in tableView: NSTableView) -> Int { return 5 } func tableView(_ tableView: NSTableView, viewFor tableColumn: NSTableColumn?, row: Int) -> NSView? { let cell = NSTableCellView() let textField1 = NSTextField(labelWithString: "hello") textField1.translatesAutoresizingMaskIntoConstraints = false let textField2 = NSTextField(wrappingLabelWithString: "world") textField2.translatesAutoresizingMaskIntoConstraints = false textField2.alignment = .right let stack = NSStackView(views: [ textField1, textField2 ]) stack.translatesAutoresizingMaskIntoConstraints = false stack.distribution = .fill cell.addSubview(stack) NSLayoutConstraint.activate([stack.topAnchor.constraint(equalTo: cell.topAnchor, constant: 0), stack.leadingAnchor.constraint(equalTo: cell.leadingAnchor, constant: 0), stack.bottomAnchor.constraint(equalTo: cell.bottomAnchor, constant: 0), stack.trailingAnchor.constraint(equalTo: cell.trailingAnchor, constant: 0)]) return cell } }
Topic: UI Frameworks SubTopic: AppKit Tags:
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Aug ’25
How can I connect NSTableCellView.textField to a SwiftUI view?
When using NSTableView or NSOutlineView, if you use an NSTableCellView and wire up the .imageView and .textField properties then you get some "free" behaviour with respect to styling and sizing of those fields. (ex: They reflect the user's preferred "Sidebar Icon Size" as selected in Settings. ) If I'm using a SwiftUI View inside an NSTableCellView, is there any way to connect a Text or Image to those properties? Consider the following pseudo code: struct MyCellView: View { let text: String let url: URL? var body: some View { HStack { Image(...) // How to indicate this is .imageView? Text(...) // How to indicate this is .textField? } } } final class MyTableCellView: NSTableCellView { private var hostingView: NSHostingView<MyCellView>! init() { self.hostingView = NSHostingView(rootView: MyCellView(text: "", url: nil)) self.addSubview(self.hostingView) } func configureWith(text: String, url: URL) { let rootView = MyCellView(text: text, url: url) hostingView.rootView = rootView // How can I make this connection? self.textField = rootView.??? self.imageView = rootView.??? } } I'm ideally looking for a solution that works on macOS 15+.
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Aug ’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
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Aug ’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:
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Aug ’25
vImageConverter_CreateWithCGImageFormat Fails with kvImageInvalidImageFormat When Trying to Convert CMYK to RGB
So I get JPEG data in my app. Previously I was using the higher level NSBitmapImageRep API and just feeding the JPEG data to it. But now I've noticed on Sonoma If I get a JPEG in the CMYK color space the NSBitmapImageRep renders mostly black and is corrupted. So I'm trying to drop down to the lower level APIs. Specifically I grab a CGImageRef and and trying to use the Accelerate API to convert it to another format (to hopefully workaround the issue... CGImageRef sourceCGImage = `CGImageCreateWithJPEGDataProvider(jpegDataProvider,` NULL, shouldInterpolate, kCGRenderingIntentDefault); Now I use vImageConverter_CreateWithCGImageFormat... with the following values for source and destination formats: Source format: (derived from sourceCGImage) bitsPerComponent = 8 bitsPerPixel = 32 colorSpace = (kCGColorSpaceICCBased; kCGColorSpaceModelCMYK; Generic CMYK Profile) bitmapInfo = kCGBitmapByteOrderDefault version = 0 decode = 0x000060000147f780 renderingIntent = kCGRenderingIntentDefault Destination format: bitsPerComponent = 8 bitsPerPixel = 24 colorSpace = (DeviceRBG) bitmapInfo = 8197 version = 0 decode = 0x0000000000000000 renderingIntent = kCGRenderingIntentDefault But vImageConverter_CreateWithCGImageFormat fails with kvImageInvalidImageFormat. Now if I change the destination format to use 32 bitsPerpixel and use alpha in the bitmap info the vImageConverter_CreateWithCGImageFormat does not return an error but I get a black image just like NSBitmapImageRep
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Aug ’25
Sleep State Notification Inconsistencies on MacBook Devices When Unplugged
There are inconsistent behaviors in sleep/wake notification callbacks across different MacBook devices and macOS versions when the device is not connected to power, with or without external displays, entering sleep mode by closing the lid, and waking up from sleep by opening the lid. When monitoring the following Objective-C notifications: NSWorkspaceScreensDidSleepNotification NSWorkspaceScreensDidWakeNotification NSWorkspaceWillSleepNotification NSWorkspaceDidWakeNotification Different devices exhibit varying notification trigger patterns: Some devices trigger all four notifications properly Some devices fail to trigger NSWorkspaceScreensDidWakeNotification Some devices fail to trigger NSWorkspaceDidWakeNotification Some devices fail to trigger NSWorkspaceWillSleepNotification These inconsistencies make it challenging to implement reliable sleep/wake detection logic across different MacBook models and macOS versions.
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Aug ’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:
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Aug ’25
How to speed-up initial UI rendering faster in AppKit?
I am developing an AppKit application in MacOS with Swift. Our application requires a complex, multi-windowed interface and must deliver a very fast, responsive experience. As a performance test, I built a sample app that creates 3 windows programmatically, each containing 500 NSTextFields (with each text-field assigned 35 different properties). Code flow: https://gist.github.com/Raunit-TW/5ac58ac9c6584f93e2ee201aa8118139 This takes around 77 milliseconds to render the windows - I need to find a way to reduce this time, as low as possible. Thanks.
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Aug ’25
[TextKit2] - Wrong document height sometimes ?
Hello 👋 I'm playing with the Apple TextKit2 sample app (particularly on macOS). I found that on some long document the evaluated height given by enumerateTextLayoutFragments API is wrong (or at least not I expect) which imply I can no longer scroll in my document even if I have not reached the end of it (which is not what I expect as you can guess). I'm clearly missing a point here. I can reproduce it on the Apple sample app by only changing the text content: https://developer.apple.com/documentation/UIKit/using-textkit-2-to-interact-with-text Using TextKit2, is it my responsability as developer to check that I've reached end of the scrollview whether not being at the end location of the document and call some specific TextKit2 API to invalidate estimation or something ? Here is an updated version of the Apple sample app with another text content that show the issue. https://drive.google.com/file/d/1jtTD84oqGAG4_A9DfqFl_yHmbLKhF1e8/view?usp=sharing Environment: Xcode 16.4 - macOS 15.6 If someone could help me with this, I would be extremely grateful. It puzzles me. NB: I've observed that resizing the window a bit seems to force a new layout and make TextKit2 returns a more accurate height, ... until you reach the end of the document.
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Aug ’25