Explore the various UI frameworks available for building app interfaces. Discuss the use cases for different frameworks, share best practices, and get help with specific framework-related questions.

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Change anchor position of view for the tvOS focus engine
I'm developing a grid of focusable elements in SwiftUI with different sizes for tvOS (similar to a tv channel grid). Because the Focus Engine calculates the next view to focus based on the center of the currently focused view, sometimes it changes focus to an unexpected view. Here's an example: Actual: Expected: Is it possible to customize the anchor point from which the focus engine traces a ray to the next view? I would prefer the leading edge in my case.
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407
Jan ’25
The @Environment(\.dismiss) value in SwiftUI for macOS does not dismiss a sheet presented by an NSWindowController.
I'm wondering what the correct, or recommended, way is to dismiss a SwiftUI that is being presented as a sheet hosted by an NSHostingController. The usual technique of invoking @Environment(\.dismiss) does not appear to work. Consider the code below. An NSWindowController is attempting to display a SwiftUI SettingsView as a sheet. The sheet is correctly presented, but the SettingsView is unable to dismiss itself. I am able to make it work by passing a closure into SettingsView that calls back to the NSWindowController but it's rather convoluted because SettingsView doesn't know the view controller that's hosting it until after SettingsView has been created, which means "finding" that view controller in the window controller to dismiss is more involved than it should be. Is there a better strategy to leverage here? final class MyViewController: NSViewController { @IBAction func buttonClicked(_ sender: NSButton) { if let presenter = window?.contentViewController { presenter.presentAsSheet(NSHostingController(rootView: SettingsView())) } } } struct SettingsView: View { @Environment(\.dismiss) private var dismiss var body: some View { VStack { Button("Cancel", role: .cancel) { dismiss() // This call does not dismiss the sheet. } .keyboardShortcut(.cancelAction) } } } Thank you. macOS 15.4.1 (24E263), Xcode 16.3 (16E140)
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85
Apr ’25
Reading large documents
Can the SwiftUI document architecture Take a file as read-only; never to be written out Take files too large for memory (multi-MB, or even GB) I wouldn't want the system to read a gigabyte size file into memory by default. If the system can use a memory-mapped Data as the representation, that'll be something I can make do. It would be even better if I could tell the system that I'll handle all the reading, all I need from it is a reference to the file's location on disk.
Topic: UI Frameworks SubTopic: SwiftUI
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40
Apr ’25
Siri Shortcuts of Siri Intent to Voice Control Parts of App
I am new to the idea of Siri Shortcuts and App Intents. What I want to do is use Siri to run a function in my app. Such as saying to Siri Zoom in map and that will then call a function in my app where I can zoom in the map. Similarly, I could say Zoom out map and it would call a function to zoom out my map. I do not need to share any sort of shortcut with the Shortcuts app. Can someone please point me in the right direction for what type of intents I need to use for this?
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85
Apr ’25
Explanation of DynamicProperty's update func in SwiftUI
Could an Apple employee that works on SwiftUI please explain the update() func in the DynamicProperty protocol? The docs have ambiguous information, e.g. "Updates the underlying value of the stored value." and "SwiftUI calls this function before rendering a view’s body to ensure the view has the most recent value." From: https://developer.apple.com/documentation/swiftui/dynamicproperty/update() How can it both set the underlying value and get the most recent value? What does underlying value mean? What does stored value mean? E.g. Is the code below correct? struct MyProperty: DynamicProperty { var x = 0 mutating func update() { // get x from external storage x = storage.loadX() } } Or should it be: struct MyProperty: DynamicProperty { let x: Int init(x: Int) { self.x = x } func update() { // set x on external storage storage.save(x: x) } } This has always been a mystery to me because of the ambigious docs so thought it was time to post a question.
Topic: UI Frameworks SubTopic: SwiftUI
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220
Jan ’25
Food Truck Sample animation issue from Table Component
Hi! I'm seeing some weird animation issues building the Food Truck sample application.^1 I'm running from macOS 15.4 and Xcode 16.3. I'm building the Food Truck application for macOS. I'm not focusing on iOS for now. The FoodTruckModel adds new Order values with an animation: // FoodTruckModel.swift withAnimation(.spring(response: 0.4, dampingFraction: 1)) { self.orders.append(orderGenerator.generateOrder(number: orders.count + 1, date: .now, generator: &generator)) } This then animates the OrdersTable when new Order values are added. Here is a small change to OrdersTable: // OrdersTable.swift - @State private var sortOrder = [KeyPathComparator(\Order.status, order: .reverse)] + @State private var sortOrder = [KeyPathComparator(\Order.creationDate, order: .reverse)] Running the app now inserts new Order values at the top. The problem is I seem to be seeing some weird animation issues here. It seems that as soon as the new Order comes in there is some kind of weird glitch where it appears as if part the animation is coming from the side instead of down from the top: What's then more weird is that if I seem to affect the state of the Table in any way then the next Order comes in with perfect animation. Scrolling the Table fixes the animation. Changing the creationData sort order from reverse to forward and back to reverse fixes the animation. Any ideas? Is there something about how the Food Truck product is built that would cause this to happen? Is this an underlying issue in the SwiftUI infra?
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60
Apr ’25
How do I maintain a stable scroll position when inserting items above in a ScrollView?
As the title says, I am not sure how to properly build an inverted ScrollView where I can safely insert items above my data ("prepend") without everything jumping around. My current code is essentially this: @State private var scrollPosition = ScrollPosition(idType: Message.ID.self) private func onMessageDidScrollIntoView(_ id: Message.ID) { let indexOfVisibleMessage = /* ... */ if indexOfVisibleMessage < 10 { fetchOlderMessages() // ^ this updates my ViewModel `messages` } } var body: some View { ScrollView { LazyVStack { ForEach(messages) { message in MessageCell(message) } }.scrollTargetLayout() } .defaultScrollAnchor(.bottom) .scrollPosition($scrollPosition) .onChange(of: scrollPosition) { oldValue, newValue in guard let visibleMessageId = scrollPosition.viewID(type: Message.ID.self) else { return } onMessageDidScrollIntoView(visibleMessageId) } } ..so if the user scrolls up to the oldest 10 messages, I start loading more and insert them at the top. The problem with this is that the ScrollView now jumps when new messages are inserted. This is because the ScrollView maintains it's Y position, but the content size changes since we are adding new items "above". I tried to play around with a few suggestions I found on StackOverflow, namely; Inverting the ScrollView (.scaleEffect(y: -1) on the ScrollView and then again on the MessageCell to counter it): This somehow jumped the x position of the ScrollView and completely breaks .contextMenu. Playing around with .onScrollGeometryChange to update scrollPosition.scrollTo(y:) when it's contentSize changes: This just didn't work and stopped the user scroll gesture/interaction. Setting scrollPosition to the Message.ID I want to keep stable before doing an update: This didn't do anything. But nothing actually worked for the reasons described above. How do you actually build these UIs in SwiftUI? I think an inverted ScrollView is quite a common UI, and obviously data has to be loaded lazily.
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107
Apr ’25
How to Visualize Data in a DataFrame Using Charts
I want to visualize the data stored in a DataFrame using various charts (barmark, sectormark, linemark, etc.). My questions are as follows: Can a DataFrame be used directly within a chart? If so, could you provide a simple example? If it cannot be used directly, what is the correct way to use it? Could you provide an example? Thank you for your help. Best regards.
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392
Jan ’25
SwiftUI Text is larger when empty
I have a simple SwiftUI Text: Text(t) .font(Font.system(size: 9)) Strangely its ideal height seems to be larger when it is empty. I initially observed this in a custom Layout container that wasn't working quite right. Eventually I looked at the height returned by v.dimensions(in:), and found that when t is non-empty the height is 11; when empty, it's 14. Subsequently I observed similar behaviour in a regular VStack container. Has anyone seen anything similar? Are there any properties that could affect this behaviour? (This is on a watch - I don't know if that matters.)
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308
Jan ’25
Title: Frequent SIGSEGV crashes in QuartzCore's copy_image (iOS 18.4) We're experiencing numerous crashes with the following signature:
Title: Frequent SIGSEGV crashes in QuartzCore's copy_image (iOS 18.4) We're experiencing numerous crashes with the following signature: Exception Codes: fault addr: 0x00000000000000e0 Crashed Thread: 0 Thread 0 0 QuartzCore CA::Render::copy_image(CGImage*, CGColorSpace*, unsigned int, double, double) + 1972 1 QuartzCore CA::Render::copy_image(CGImage*, CGColorSpace*, unsigned int, double, double) + 1260 2 QuartzCore CA::Render::prepare_image(CGImage*, CGColorSpace*, unsigned int, double) + 24 3 QuartzCore CA::Layer::prepare_contents(CALayer*, CA::Transaction*) + 220 4 QuartzCore CA::Layer::prepare_commit(CA::Transaction*) + 284 5 QuartzCore CA::Context::commit_transaction(CA::Transaction*, double, double*) + 488 6 QuartzCore CA::Transaction::commit() + 644 7 UIKitCore ___34-[UIApplication _firstCommitBlock]_block_invoke_2 + 36 8 CoreFoundation ___CFRUNLOOP_IS_CALLING_OUT_TO_A_BLOCK__ + 28 9 CoreFoundation ___CFRunLoopDoBlocks + 352 10 CoreFoundation ___CFRunLoopRun + 868 11 CoreFoundation _CFRunLoopRunSpecific + 572 12 GraphicsServices _GSEventRunModal + 168 13 UIKitCore -[UIApplication _run] + 816 14 UIKitCore _UIApplicationMain + 336 15 kugou _main + 132 16 dyld __dyld_process_info_create + 33284 Observations: 1.Crashes consistently occur in Core Animation's image processing pipeline 2.100% of occurrences are on iOS 18.4 devices 3.Crash signature suggests memory access violation during image/copy operations 4.Not tied to any specific device model Questions for Apple: 1.Is this crash pattern recognized as a known issue in iOS 18.4? 2.Are there specific conditions that could trigger SEGV_ACCERR in CA::Render::copy_image? 3.Could this be related to color space handling or image format requirements changes? 4.Any recommended workarounds while waiting for a system update?
Topic: UI Frameworks SubTopic: UIKit Tags:
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120
Apr ’25
UIInputView not being deallocated
I am experiencing memory leaks in my iOS app that seem to be related to an issue between UIInputView and _UIInputViewContent. After using the memory graph, I'm seeing that instances of these objects aren't being deallocated properly. The UIInputViewController whichs holds the inputView is being deallocated properly along with its subviews.I have tried to remove all of UIInputViewController's subviews and their functions but the uiInputView is not being deallocated. The current setup of my app is a collectionView with multiple cell,each possessing a textfield with holds a UIInputViewController.When i scroll up or down,the views are being reused as expected and the number of UIInputViewController stays consistent with the number of textfields.However the number of inputView keeps increasing referencing solely _UIInputViewContent. class KeyboardViewController: UIInputViewController { // Callbacks var key1: ((String) -> Void)? var key2: (() -> Void)? var key3: (() -> Void)? var key4: (() -> Void)? private lazy var buttonTitles = [ ["1", "2", "3"], ["4", "5", "6"], ["7", "8", "9"] ] override func viewDidLoad() { super.viewDidLoad() setupKeyboard() } lazy var mainStackView: UIStackView = { let mainStackView = UIStackView() mainStackView.axis = .vertical mainStackView.distribution = .fillEqually mainStackView.spacing = 16 mainStackView.translatesAutoresizingMaskIntoConstraints = false return mainStackView }() private func setupKeyboard() { let keyboardView = UIView(frame:CGRect(x: 0, y: 0, width: UIScreen.main.bounds.width, height: 279.0)) keyboardView.addSubview(mainStackView) NSLayoutConstraint.activate([ mainStackView.topAnchor.constraint(equalTo: keyboardView.topAnchor, constant: 16), mainStackView.leadingAnchor.constraint(equalTo: keyboardView.leadingAnchor, constant: 0), mainStackView.trailingAnchor.constraint(equalTo: keyboardView.trailingAnchor, constant: -24), mainStackView.bottomAnchor.constraint(equalTo: keyboardView.bottomAnchor, constant: -35) ]) // Create rows for (_, _) in buttonTitles.enumerated() { let rowStackView = UIStackView() rowStackView.axis = .horizontal rowStackView.distribution = .fillEqually rowStackView.spacing = 1 // Create buttons for each row for title in rowTitles { let button = createButton(title: title) rowStackView.addArrangedSubview(button) } mainStackView.addArrangedSubview(rowStackView) } self.view = keyboardView } private func createButton(title: String) -> UIButton { switch title { ///returns a uibutton based on title } } // MARK: - Button Actions @objc private func numberTapped(_ sender: UIButton) { if let number = sender.title(for: .normal) { key1?(number) } } @objc private func key2Called() { key2?() } @objc private func key3Called() { key3?() } @objc private func key4Called() { key4?() } deinit { // Clear any strong references key1 = nil key2 = nil key3 = nil key4 = nil for subview in mainStackView.arrangedSubviews { if let stackView = subview as? UIStackView { for button in stackView.arrangedSubviews { (button as? UIButton)?.removeTarget(self, action: nil, for: .allEvents) } } } mainStackView.removeFromSuperview() } } Environment iOS 16.3 Xcode 18.3.1 Any insights would be greatly appreciated as this is causing noticeable memory growth in my app over time.
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70
Apr ’25
CATransaction commit() crashed on background thread [EXC_BREAKPOINT: com.apple.root.****-qos.cooperative]
Problem Description We are developing a app for iOS and iPadOS that involves extensive custom drawing of paths, shapes, texts, etc. To improve drawing and rendering speed, we use CARenderer to generate cached images (CGImage) on a background thread. We adopted this approach based on this StackOverflow post: https://stackoverflow.com/a/75497329/9202699. However, we are experiencing frequent crashes in our production environment that we can hardly reproduce in our development environment. Despite months of debugging and seeking support from DTS and the Apple Feedback platform, we have not been able to fully resolve this issue. Our recent crash reports indicate that the crashes occur when calling CATransaction.commit(). We suspect that CATransaction may not be functioning properly outside the main thread. However, based on feedback from the Apple Feedback platform, we were advised to use CATransaction.begin() and CATransaction.commit() on a background thread. If anyone has any insights, we would greatly appreciate it. Code Sample The line CATransaction.commit() is causing the crash: [EXC_BREAKPOINT: com.apple.root.****-qos.cooperative] private let transactionLock = NSLock() // to ensure one transaction at a time private let device = MTLCreateSystemDefaultDevice()! @inline(never) static func drawOnCGImageWithCARenderer( layerRect: CGRect, itemsToDraw: [ItemsToDraw] ) -> CGImage? { // We have encapsulated everything related to CALayer and its // associated creations and manipulations within CATransaction // as suggested by engineers from Apple Feedback Portal. transactionLock.lock() CATransaction.begin() // Create the root layer. let layer = CALayer() layer.bounds = layerRect layer.masksToBounds = true // Add one sublayer for each item to draw itemsToDraw.forEach { item in // We have thousands or hundred thousands of drawing items to add. // Each drawing item may produce a CALayer, CAShapeLayer or CATextLayer. // This is also why we want to utilise CARenderer to leverage GPU rendering. layer.addSublayer( item.createCALayerOrCATextLayerOrCAShapeLayer() ) } // Create MTLTexture and CARenderer. let textureDescriptor = MTLTextureDescriptor.texture2DDescriptor( pixelFormat: .rgba8Unorm, width: Int(layer.frame.size.width), height: Int(layer.frame.size.height), mipmapped: false ) textureDescriptor.usage = [MTLTextureUsage.shaderRead, .shaderWrite, .renderTarget] let texture = device.makeTexture(descriptor: textureDescriptor)! let renderer = CARenderer(mtlTexture: texture) renderer.bounds = layer.frame renderer.layer = layer.self /* ********************************************************* */ // From our crash report, this is where the crash happens. CATransaction.commit() /* ********************************************************* */ transactionLock.unlock() // Rendering layers onto MTLTexture using CARenderer. renderer.beginFrame(atTime: 0, timeStamp: nil) renderer.render() renderer.endFrame() // Draw MTLTexture onto image. guard let colorSpace = CGColorSpace(name: CGColorSpace.sRGB), let ciImage = CIImage(mtlTexture: texture, options: [.colorSpace: colorSpace]) else { return nil } // Convert CIImage to CGImage. let context = CIContext() return context.createCGImage(ciImage, from: ciImage.extent) }
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494
Jan ’25
macos 15, savepanel return the wrong path when saving files occasionally
macOS: 15.0 macFUSE: 4.8.3 I am using rclone + macFUSE and mount my netdisk where it has created three subdirectories in its root directory: /user, /share, and /group. When I save a file to /[root]/user using NSSavePanel and name it test.txt, I expect the file to be saved as: /[root]/user/test.txt However, occasionally, the delegate method: - (BOOL)panel:(id)sender validateURL:(NSURL *)url error:(NSError **)outError { } returns an incorrect path: /[root]/test.txt This issue only occurs when selecting /user. The same operation works correctly for /share and /group. Is there any logs I could provide to help solving this issue? Many thanks!
Topic: UI Frameworks SubTopic: AppKit Tags:
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370
Feb ’25
view controller life cycle bug in xcode 16 ios 18
hi does any one know if there changes in lifecycle in xcode 16 ios 18 cause i notice that my view will appear does what view didappear use to do in older version and it kind of a problem cause all the rest of ios work diffrently does anyone else found a problem with it? or does anyone know if there was a known change to life cycles
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435
Jan ’25
RePlayKit:screen recording method return sampleBuffer is nil
I want record screen in my app,the method startCaptureWithHandler:completionHandler:,the sampleBuffer, It is supposed to exist but it has become nil.Not only that,but there‘s another problem,when I want to stop recording and save the video,I will check [RPScreenRecorder sharedRecorder].recording first, it will be false sometime,that problems are unusual in iOS 18.3.2 iPhoneXs Max,and unexpected,here is my code -(void)startCaptureScreen { NSLog(@"AKA++ startCaptureScreen"); if ([[RPScreenRecorder sharedRecorder] isRecording]) { return; } //屏幕录制 [[RPScreenRecorder sharedRecorder]setMicrophoneEnabled:YES]; NSLog(@"AKA++ MicrophoneEnabled AAAA startCaptureScreen"); [[RPScreenRecorder sharedRecorder]setCameraEnabled:YES]; [[RPScreenRecorder sharedRecorder] startCaptureWithHandler:^(CMSampleBufferRef _Nonnull sampleBuffer, RPSampleBufferType bufferType, NSError * _Nullable error) { if(self.assetWriter == nil){ if (self.AVAssetWriterStatus == 0) { [self setupAssetWriterAndStartWith:sampleBuffer]; } } if (self.AVAssetWriterStatus != 2) { return; } if (error) { // deal with error return; } if (self.assetWriter.status != AVAssetWriterStatusWriting) { [self assetWriterAppendSampleBufferFailWith:bufferType]; return; } if (bufferType == RPSampleBufferTypeVideo) { if(self.assetWriter.status == 0 ||self.assetWriter.status > 2){ } else if(self.videoAssetWriterInput.readyForMoreMediaData == YES){ BOOL success = [self.videoAssetWriterInput appendSampleBuffer:sampleBuffer]; } } if (bufferType == RPSampleBufferTypeAudioMic) { if(self.assetWriter.status == 0 ||self.assetWriter.status > 2){ } else if(self.audioAssetWriterInput.readyForMoreMediaData == YES){ BOOL success = [self.audioAssetWriterInput appendSampleBuffer:sampleBuffer]; } } } completionHandler:^(NSError * _Nullable error) { //deal with error }]; } and than ,when want to save it : -(void)stopRecording { if([[RPScreenRecorder sharedRecorder] isRecording]){ // The problem is sporadic,recording action failed,it makes me confused } [[RPScreenRecorder sharedRecorder] stopCaptureWithHandler:^(NSError * _Nullable error) { if(!error) { //post message } }]; }
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76
Apr ’25
Monitoring of the paste(GUI based) operation
I am working on the EndPoint DLP solution project. So I want to monitor the paste operation peformed by the user. So when he uses the keyboard keys then I can monitor them using the event callback. But if user uses the GUI for pasting the data then how can I monitor that ?
Topic: UI Frameworks SubTopic: General
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226
Jan ’25
Can We Detect When Running Behind a Slide Over Window?
I'm trying to determine if it’s possible to detect when a user interacts with a Slide Over window while my app is running in the background on iPadOS. I've explored lifecycle methods such as scenePhase and various UIApplication notifications (e.g., willResignActiveNotification) to detect focus loss, but these approaches don't seem to capture the event reliably. Has anyone found an alternative solution or workaround for detecting this specific state change? Any insights or recommended practices would be greatly appreciated.
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95
Mar ’25
MVVM design and data dependency
According to the MVVM design pattern, one of my views depends on many properties in my model. Can I use logic like @published var model = MyModel()? Will there be a large performance loss? Will the UI be refreshed when other unrelated properties in the model are modified? What is the best practice in this case?
Topic: UI Frameworks SubTopic: General
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248
Jan ’25