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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Should SwiftUI view models in Swift 6 be both @Observable and @MainActor?
Hi, In the WWDC25 session Elevate an app with Swift concurrency (timestamps: 8:04 and later), the StickerViewModel is shown annotated with @Observable but not @MainActor. The narration mentions that updates happen on the main thread, but that guarantee is left implicit in the calling code. In Swift 6, though, one of the major benefits is stronger compiler enforcement against data races and isolation rules. If a view model were also annotated with @MainActor, then the compiler could enforce that observable state is only updated on the main actor, preventing accidental background mutations or updates that can cause data races between nonisolated and main actor-isolated uses. Since @Observable already signals that state changes are intended to be observed (and in practice, usually by views), it seems natural that such types should also be main-actor isolated. Otherwise, we’re left with an implicit expectation that updates will always come from the main thread, but without the compiler’s help in enforcing that rule. This also ties into the concept of local reasoning that was emphasized in other Swift 6 talks (e.g. Beyond the basics of structured concurrency). With @MainActor, I can look at a view model and immediately know that all of its state is main-actor isolated. With only @Observable, that guarantee is left out, which feels like it weakens the clarity that Swift 6 is trying to promote. Would it be considered a best practice in Swift 6 to use both @Observable and @MainActor for UI-facing view models? Or is the intention that SwiftUI developers should rely on calling context to ensure main-thread updates, even if that means the compiler cannot enforce isolation? Thanks!
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277
Aug ’25
TextKit 2 calls NSTextLayoutFragment's draw method too often
The following is verbatim of a feedback report (FB19809442) I submitted, shared here as someone else might be interested to see it (I hate the fact that we can't see each other's feedbacks). On iOS 16, TextKit 2 calls NSTextLayoutFragment's draw(at:in:) method once for the first paragraph, but for every other paragraph, it calls it continuously on every scroll step in the UITextView. (The first paragraph is not cached; its draw is called again when it is about to be displayed again, but then it is again called only once per its lifecycle.) On iOS 17, the behavior is similar; the draw method gets called once for the 1st and 2nd paragraph, and for every other paragraph it again gets called continuously as a user scrolls a UITextView. On iOS 18 (and iOS 26 beta 4), TextKit 2 calls the layout fragment's draw(at:in:) on every scroll step in the UITextView, for all paragraphs. This results in terrible performance. TextKit 2 is promised to bring many performance benefits by utilizing the viewport - a new concept that represents the visible area of a text view, along with a small overscroll. However, having the draw method being constantly called almost negates all the performance benefits that viewport brings. Imagine what could happen if someone needs to add just a bit of logic to that draw method. FPS drops significantly and UX is terribly degraded. I tried optimizing this by only rendering those text line fragments which are in the viewport, by using NSTextViewportLayoutController.viewportBounds and converting NSTextLineFragment.typographicBounds to the viewport-relative coordinate space (i.e. the coordinate space of the UITextView itself). However, this patch only works on iOS 18 where the draw method is called too many times, as the viewport changes. (I may have some other problems in my implementation, but I gave up on improving those, as this can't work reliably on all OS versions since the underlying framework isn't calling the method consistently.) Is this expected? What are our options for improving performance in these areas?
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205
Aug ’25
Issue with .itemProvider on macOS 15.1
I have a List with draggable items. According to this thread (https://developer.apple.com/forums/thread/664469) I had to use .itemProvider instead of .onDrag, because otherwise the selection of the list will not work anymore. The items in my list refer to a file URL. So the dragging allowed to copy the files to the destination of the drag & drop. Therefore I used this code .itemProvider { let url = ....... // get the url with an internal function return NSItemProvider(object: url as NSURL) } Since the update to macOS 15.1 this way isn't working anymore. It just happens nothing. I also tried to use .itemProvider { let url = .... return NSItemProvider(contentsOf: url) ?? NSItemProvider(object: url as NSURL) } but this doesn't work too. The same way with .onDrag works btw. .onDrag { let url = ....... // get the url with an internal function return NSItemProvider(object: url as NSURL) } but as I wrote, this will break the possibility to select or to use the primaryAction of the .contextMenu. Is this a bug? Or is my approach wrong and is there an alternative?
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450
Feb ’25
Modal Presentation in UIKit Adds Solid Background in iOS 26
Hello, I have a number of UIViewControllers that are presented as follows: vc.modalPresentationStyle = UIModalPresentationStyle.popover vc.modalTransitionStyle = UIModalTransitionStyle.coverVertical self.present(vc, animated: true, completion: nil) The VC is designed from a Storyboard where I set the 'view' of the VC to have a .clear 'backgroundColor', I have a smaller 'Alert View' added as a subview which is what the user interacts with. In iOS 13 - iOS 18 this would present modally, not take up the entire screen and allow the user to see relevant context from the screen underneath. In iOS 26 Beta 5 and every beta prior the system injects a 'UIDropShadowView' in the View Hierarchy, this view has a solid color backdrop, either white/black depending on light/dark mode. This causes all underlying content to be blocked and essentially forces a full screen modal presentation despite the existing design. I am looking for a way to remove this solid color. I'm not sure if it's intentional or a bug / oversight. I have been able to remove it in a hacky way, I cycle the view hierarchy to find 'UIDropShadowView' and set it's backdrop to transparent. However when you swipe down to partially dismiss the view it turns to Liquid Glass when it is around 75% dismissed and then resets the background color to white/black. I tried creating a custom UIViewControllerTransitioningDelegate so that I could re-implement the existing behaviour but it's incredibly difficult to mimic the partial dismiss swipe down effect on the VC. I have also tried changing my presentation to: vc.modalPresentationStyle = UIModalPresentationStyle.overFullScreen vc.modalTransitionStyle = UIModalTransitionStyle.crossDissolve This works but then the user loses the ability to interactively swipe to dismiss. Any help would be appreciated. Thank you!
Topic: UI Frameworks SubTopic: UIKit Tags:
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405
Aug ’25
How to get the frame or insets of the new iPadOS 26 window control buttons (close, minimize, fullscreen)?
In iPadOS 26, Apple introduced macOS-style window control buttons (close, minimize, fullscreen) for iPad apps running in a floating window. I'm working on a custom toolbar (UIView) positioned near the top of the window, and I'd like to avoid overlapping with these new controls. However, I haven't found any public API that exposes the frame, layout margins, or safe area insets related to this new UI region. I've checked the window's safeAreaInsets, additionalSafeAreaInsets, and UIWindowSceneDelegate APIs, but none of them seem to reflect the area occupied by these buttons. Is there an officially supported way to: Get the layout information (frame, insets, or margins) of the window control buttons on iPadOS 26? Or, is there a system-defined guideline or padding value we should use to avoid overlapping this new UI? Any clarification or guidance would be appreciated!
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583
Aug ’25
Swift Charts: How to prevent scroll position jump when loading more data dynamically
I'm implementing infinite scrolling with Swift Charts where additional historical data loads when scrolling near the beginning of the dataset. However, when new data is loaded, the chart's scroll position jumps unexpectedly. Current behavior: Initially loads 10 data points, displaying the latest 5 When scrolling backwards with only 3 points remaining off-screen, triggers loading of 10 more historical points After loading, the scroll position jumps to the 3rd position of the new dataset instead of maintaining the current view Expected behavior: Scroll position should remain stable when new data is loaded User's current view should not change during data loading Here's my implementation logic using some mock data: import SwiftUI import Charts struct DataPoint: Identifiable { let id = UUID() let date: Date let value: Double } class ChartViewModel: ObservableObject { @Published var dataPoints: [DataPoint] = [] private var isLoading = false init() { loadMoreData() } func loadMoreData() { guard !isLoading else { return } isLoading = true let newData = self.generateDataPoints( endDate: self.dataPoints.first?.date ?? Date(), count: 10 ) self.dataPoints.insert(contentsOf: newData, at: 0) self.isLoading = false print("\(dataPoints.count) data points.") } private func generateDataPoints(endDate: Date, count: Int) -> [DataPoint] { var points: [DataPoint] = [] let calendar = Calendar.current for i in 0..<count { let date = calendar.date( byAdding: .day, value: -i, to: endDate ) ?? endDate let value = Double.random(in: 0...100) points.append(DataPoint(date: date, value: value)) } return points.sorted { $0.date < $1.date } } } struct ScrollableChart: View { @StateObject private var viewModel = ChartViewModel() @State private var scrollPosition: Date @State private var scrollDebounceTask: Task<Void, Never>? init() { self.scrollPosition = .now.addingTimeInterval(-4*24*3600) } var body: some View { Chart(viewModel.dataPoints) { point in BarMark( x: .value("Time", point.date, unit: .day), y: .value("Value", point.value) ) } .chartScrollableAxes(.horizontal) .chartXVisibleDomain(length: 5 * 24 * 3600) .chartScrollPosition(x: $scrollPosition) .chartXScale(domain: .automatic(includesZero: false)) .frame(height: 300) .onChange(of: scrollPosition) { oldPosition, newPosition in scrollDebounceTask?.cancel() scrollDebounceTask = Task { try? await Task.sleep(for: .milliseconds(300)) if !Task.isCancelled { checkAndLoadMoreData(currentPosition: newPosition) } } } } private func checkAndLoadMoreData(currentPosition: Date?) { guard let currentPosition, let earliestDataPoint = viewModel.dataPoints.first?.date else { return } let timeInterval = currentPosition.timeIntervalSince(earliestDataPoint) if timeInterval <= 3 * 24 * 3600 { viewModel.loadMoreData() } } } I attempted to compensate for this jump by adding: scrollPosition = scrollPosition.addingTimeInterval(10 * 24 * 3600) after viewModel.loadMoreData(). However, this caused the chart to jump in the opposite direction by 10 days, rather than maintaining the current position. What's the problem with my code and how to fix it?
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534
Jun ’25
Critical Issue in iOS 18 Beta: UITabBarController Child View Controller Incorrectly Added as UITabBarItem, Leading to Application Crash
I am writing to report an issue I encountered with iOS 18 beta that affects my application, which has been available on the App Store for over two years and currently has over 60,000 active users. My application utilizes a UITabBarController to manage multiple tabs, where each tab hosts a UIViewController embedded within a UINavigationController. The application operates in two different states, where users may have either 5, 4, or 3 tabBarItems depending on their configuration. The issue arises when fewer than 5 tabs are present. In these cases, I add child view controllers to the UITabBarController to ensure they are displayed above the tab bar, rather than below it. The relevant code snippet is as follows: tabBarController.addChild(childController) tabBarController.view.addSubview(childController.view) Prior to iOS 18, this implementation functioned as expected. However, with the release of iOS 18, adding a child view controller to the UITabBarController results in the child being incorrectly added as a UITabBarItem. This misbehavior leads to an application crash when the unintended tab is selected. The crash trace is as follows: "Inconsistency in UITabBar items and view controllers detected. No view controller matches the UITabBarItem '<UITabBarItem: 0x142d9c480> selected'." I have attached screenshots from iOS 18 and previous versions to illustrate the issue, which compares the expected behavior in earlier iOS versions with the problematic behavior in iOS 18. I appreciate your attention to this matter and look forward to any guidance or resolution you can provide.
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2.5k
Dec ’24
On iPadOS 26 beta, the navigation bar can appear inset underneath the status bar (FB18241928)
On iPadOS 26 beta, the navigation bar can appear inset underneath the status bar (FB18241928) This bug does not happen on iOS 18. This bug occurs when a full screen modal view controller without a status bar is presented, the device orientation changes, and then the full screen modal view controller is dismissed. This bug appears to happen only on iPad, and not on iPhone. This bug happens both in the simulator and on the device. Thank you for investigating this issue.
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Aug ’25
SwiftUI View cannot conform custom Equatable protocol in Swift 6.
In Swift 6, stricter concurrency rules can lead to challenges when making SwiftUI views conform to Equatable. Specifically, the == operator required for Equatable must be nonisolated, which means it cannot access @MainActor-isolated properties. This creates an error when trying to compare views with such properties: Error Example: struct MyView: View, Equatable { let title: String let count: Int static func ==(lhs: MyView, rhs: MyView) -> Bool { // Accessing `title` here would trigger an error due to actor isolation. return lhs.count == rhs.count } var body: some View { Text(title) } } Error Message: Main actor-isolated operator function '==' cannot be used to satisfy nonisolated protocol requirement; this is an error in the Swift 6 language mode. Any suggestions? Thanks FB: FB15753655 (SwiftUI View cannot conform custom Equatable protocol in Swift 6.)
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966
Mar ’25
NavigationSplitView not fully supported on smaller (SE) iPhones
My SwiftUI code runs fine on macOS, iOS(iPad) and larger iPhones, but will not display the detail view on smaller iPhones. Is there a way to force the smaller iPhones to display the detail view? And if not, When I put the App on the Apple store, for sale, will the Apple store be smart enough to flag the App as not appropriate for smaller iPhones, such as the SE (2nd and 3rd gen.) and prevent downloads? Thanks in advance for any guidance.
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1.1k
Jul ’25
Cannot get drop action to trigger (Xcode 26 beta 3)
I'm unable to find the right combination modifiers to get drag and drop to work using the new .draggable(containerItemID:) and dragContainer(for:in:selection:_:) modifiers. The drag is initiated with the item's ID, the item is requested from the .dragContainer modifier, but the drop closure is never triggered. Minimal repro: struct Item: Identifiable, Codable, Transferable { var id = UUID() var value: String static var transferRepresentation: some TransferRepresentation { CodableRepresentation(contentType: .tab) } } struct DragDrop: View { @State var items: [Item] = [ Item(value: "Hello"), Item(value: "world"), Item(value: "something"), Item(value: "else") ] var body: some View { List(items) { item in HStack { Text(item.value) Spacer() } .contentShape(Rectangle()) .draggable(containerItemID: item.id) .dropDestination(for: Item.self) { items, session in print("Drop: \(items)") } } .dragContainer(for: Item.self) { itemID in print("Drag: \(itemID)") return items.filter { itemID == $0.id } } } } #Preview("Simple") { DragDrop() }
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130
Jul ’25
NSRulerView's background color and transparency (macOS 26)
When I compiled my legacy project with Tahoe's macOS 26 SDK, NSRulerViews are showing a very different design: Under prior macOS versions the horizontal and verrical ruler's background were blurring the content view, which was extending under the rulers, showing through their transparency. With Tahoe the horizontal ruler is always reflecting the scrollview's background color, showing the blurred content view beneath. And the vertical ruler is always completely transparent (without any blurring), showing the content together with the ruler's markers and ticks. It's difficult to describe, I'll try to replicate this behavior with a minimal test project, and probably file a bug report / enhancement request. But before I take next steps, can anyone confirm this observation? Maybe it is an intentional design decision by Apple?
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294
Nov ’25
ScrollView + LazyVStack + dynamic height views cause scroll glitches on iOS 26
I’m seeing unexpected scroll behavior when embedding a LazyVStack with dynamically sized views inside a ScrollView. Everything works fine when the item height is fixed (e.g. colored squares), but when I switch to text views with variable height, the scroll position jumps and glitches—especially when the keyboard appears or disappears. This only happens on iOS 26, it works fine on iOS 18. Working version struct Model: Identifiable { let id = UUID() } struct ModernScrollView: View { @State private var models: [Model] = [] @State private var scrollPositionID: String? @State private var text: String = "" @FocusState private var isFocused // MARK: - View var body: some View { scrollView .safeAreaInset(edge: .bottom) { controls } .task { reset() } } // MARK: - Subviews private var scrollView: some View { ScrollView { LazyVStack { ForEach(models) { model in SquareView(color: Color(from: model.id)) .id(model.id.uuidString) } } .scrollTargetLayout() } .scrollPosition(id: $scrollPositionID) .scrollDismissesKeyboard(.interactively) .defaultScrollAnchor(.bottom) .onTapGesture { isFocused = false } } private var controls: some View { VStack { HStack { Button("Add to top") { models.insert(contentsOf: makeModels(3), at: 0) } Button("Add to bottom") { models.append(contentsOf: makeModels(3)) } Button("Reset") { reset() } } HStack { Button { scrollPositionID = models.first?.id.uuidString } label: { Image(systemName: "arrow.up") } Button { scrollPositionID = models.last?.id.uuidString } label: { Image(systemName: "arrow.down") } } TextField("Input", text: $text) .padding() .background(.ultraThinMaterial, in: .capsule) .focused($isFocused) .padding(.horizontal) } .padding(.vertical) .buttonStyle(.bordered) .background(.regularMaterial) } // MARK: - Private private func makeModels(_ count: Int) -> [Model] { (0..<count).map { _ in Model() } } private func reset() { models = makeModels(3) } } // MARK: - Color+UUID private extension Color { init(from uuid: UUID) { let hash = uuid.uuidString.hashValue let r = Double((hash & 0xFF0000) >> 16) / 255.0 let g = Double((hash & 0x00FF00) >> 8) / 255.0 let b = Double(hash & 0x0000FF) / 255.0 self.init(red: abs(r), green: abs(g), blue: abs(b)) } } Not working version When I replace the square view with a text view that generates random multiline text: struct Model: Identifiable { let id = UUID() let text = generateRandomText(range: 1...5) // MARK: - Utils private static func generateRandomText(range: ClosedRange<Int>) -> String { var result = "" for _ in 0..<Int.random(in: range) { if let sentence = sentences.randomElement() { result += sentence } } return result.trimmingCharacters(in: .whitespaces) } private static let sentences = [ "Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.", "Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.", "Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur.", "Excepteur sint occaecat cupidatat non proident, sunt in culpa qui officia deserunt mollit anim id est laborum." ] } and use it like this: ForEach(models) { model in Text(model.text) .padding() .multilineTextAlignment(.leading) .background(Color(from: model.id)) .id(model.id.uuidString) } Then on iOS 26, opening the keyboard makes the scroll position jump unpredictably. It is more visible if you play with the app, but I could not upload a video here. Environment Xcode 26.0.1 - Simulators and devices on iOS 26.0 - 18.0 Questions Is there any known change in ScrollView / scrollPosition(id:) behavior on iOS 26 related to dynamic height content? Am I missing something in the layout setup that makes this layout unstable with variable-height cells? Is there a workaround or recommended approach for keeping scroll position stable when keyboard appears?
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312
Nov ’25
iOS 26 regression: Slider does not respect step parameter
In iOS 26, the Slider control no longer respects the step parameter. For example, import SwiftUI struct ContentView: View { @State private var sliderValue: CGFloat = 16 var body: some View { Slider( value: $sliderValue, in: 0...100, step: 5, onEditingChanged: { editing in print(sliderValue) } ) } } In iOS 18, this prints values like 5, 35, 60, 95, etc. In iOS 26.0 (release version), this prints floats that are not rounded to the nearest 5, and the slider does not snap to values ending in 5. Feedback report number: FB20320542
Topic: UI Frameworks SubTopic: SwiftUI
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4
309
Nov ’25
SwiftUi Picker in WatchOS throws Scrollview Error when using Digital Crown
The following WatchOs App example is very short, but already not functioning as it is expected, when using Digital Crown (full code): import SwiftUI struct ContentView: View { let array = ["One","Two","Three","Four"] @State var selection = "One" var body: some View { Picker("Array", selection: $selection) { ForEach(array, id: \.self) { Text($0) } } } } The following 2 errors are thrown, when using Digital Crown for scrolling: ScrollView contentOffset binding has been read; this will cause grossly inefficient view performance as the ScrollView's content will be updated whenever its contentOffset changes. Read the contentOffset binding in a view that is not parented between the creator of the binding and the ScrollView to avoid this. Error: Error Domain=NSOSStatusErrorDomain Code=-536870187 "(null)" Any help appreciated. Thanks a lot.
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5
1.1k
Mar ’25
App Shortcuts: Invalid parameter type. AppEntity and AppEnum are the only allowed types...
Hi! So while Date is supported for @Parameter in an App Intent, I just discovered that Xcode will not let me use use it in a parametrized App Shortcut phrase. In my case, I would like to give the option to say "today", tomorrow", or "day after tomorrow" for the date. Am I missing something? Any hints on the best way to approach this?
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973
Oct ’25
A specific image fails to load using UIImageView on iOS 16, but loads normally on systems below iOS 16.
A specific image fails to load properly using UIImageView on iOS 16 and later systems, but loads normally on iOS 15 and earlier versions. Similarly, on Mac computers, this image cannot be opened on MacOS 13 and later, whereas it opens without issue on MacOS 12 and earlier. I am curious about the reasons behind this differing behavior on both iPhone and Mac.
6
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475
Feb ’25