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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Apple Maps annotations and markers
In Apple's Maps app, an annotation is made up of a circle shape or rounded rectangles with a glyph-image. When selecting an annotation, the annotation animates into a balloon marker (see attached GIF). How does Apple Maps solve this - from custom annotation to balloon marker with spring animation? I switched my Maps implementation from SwiftUI to UIKit with a UIViewRepresentable to support annotation clustering - and it works beautifully. But how to subclass an MKAnnotationView (or MKMarkerAnnotationView <- the balloon) to enable selection and animation as in Apple Maps? MKMarkerAnnotationView only show balloon markers and I tried everything inside MKAnnotationView (CALayer, etc.)
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418
Feb ’25
Unable to display SwiftUI View Previews in a Static Framework target
Hello, I am currently encountering an issue where SwiftUI View Previews cannot be displayed when the View is defined in a Static Framework target. This issue only occurs under specific conditions. Environment Xcode: 16.2 Scheme Structure: MainApp Test Target: TestHogeFeature Test Setting: Gather coverage (Code coverage collection) enabled(all) Target Structure: MainApp (Application target) Dependencies: [HogeFeature, Core] HogeFeature (Static Framework target) Dependencies: [Core] Core (Framework target) Dependencies: None TestHogeFeature (Unit test target) Dependencies: [HogeFeature] Summary I am currently working on a SwiftUI-based project and have encountered an issue where Previews fail to display under specific conditions. Below are the details: Issue In the MainApp scheme, when the code coverage collection setting (Gather coverage for) is enabled, Previews for SwiftUI Views within the HogeFeature (Static Framework) target fail to display correctly. However, the issue is resolved by taking one of the following actions: Change HogeFeature from a Static Framework to a Dynamic Framework. Remove the build setting MACH_O_TYPE: staticlib Disable the Gather coverage setting in the MainApp scheme. I have attached the actual error log from the failed Preview. preview error log Questions Why does this issue occur only when using a Static Framework with code coverage enabled? Is there any way to resolve this issue while maintaining the current configuration (Static Framework with code coverage enabled)? I would appreciate any advice or insights regarding the cause and potential solutions.
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512
Jan ’25
Publishing changes from within view updates is not allowed - SwiftUI with ARKit
Hello, I’m encountering the error "Publishing changes from within view updates is not allowed, this will cause undefined behavior". while developing an app using SwiftUI and ARKit. I have a ObjectTracking class where I update some @Published variables inside a function called processObjectAttributes after detecting objects. However, when I try to update these state variables in the View (like isPositionChecked, etc.), the error keeps appearing. Here is a simplified version of my code: class ObjectTracking: ObservableObject { @Published var isPositionChecked: Bool = false @Published var isSizeChecked: Bool = false @Published var isOrientationChecked: Bool = false func checkAttributes(objectAnchor: ARObjectAnchor, _ left: ARObjectAnchor.AttributeLocation, _ right: ARObjectAnchor.AttributeLocation? = nil, threshold: Float) -> Bool { let attributes = objectAnchor.attributes guard let leftValue = attributes[left]?.floatValue else { return false } let rightValue = right != nil ? attributes[right!]?.floatValue ?? 0 : 0 return leftValue > threshold && (right == nil || rightValue > threshold) } func isComplete(objectAnchor: ARObjectAnchor) -> Bool { isPositionChecked = checkAttributes(objectAnchor: objectAnchor, .positionLeft, .positionRight, threshold: 0.5) isSizeChecked = checkAttributes(objectAnchor: objectAnchor, .sizeLeft, .sizeRight, threshold: 0.3) isOrientationChecked = checkAttributes(objectAnchor: objectAnchor, .orientationLeft, .orientationRight, threshold: 0.3) return isPositionChecked && isSizeChecked && isOrientationChecked } func processObjectAttributes(objectAnchor: ARObjectAnchor) { currentObjectAnchor = objectAnchor } } In my View, I am using @ObservedObject to observe the state of these variables, but the error persists when I try to update them during view rendering. Could anyone help me understand why this error occurs and how to avoid it? I understand that state should not be updated during view rendering, but I can’t find a solution that works in this case. Thank you in advance for your help!
Topic: UI Frameworks SubTopic: SwiftUI Tags:
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346
Jan ’25
ishidden not working
I set the isHidden property of a view in traitCollectionDidChange and found that sometime it does not take effect after being set(value of isHidden actually not changed either). It looks like the setting does not take effect when triggered an even number of times, but it is normal when triggered an odd number of times. When setting isHidden, what actually goes into is [UIView (Rendering) setHidden:], which internally calls [UIView _ bitFlagValueAfterIncrementingHiddenManagement CountForKey: withIncrement: bitFlagValue:] to handle the relevant logic of "_UIViewPendingHiddenCount". Is this issue related to this part of the processing? returning 0 after calling seems normal This view is a UIStackView, and it is uncertain whether it is related to the type of view
Topic: UI Frameworks SubTopic: UIKit Tags:
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371
Jan ’25
How to initialize @Observable object in View via @State?
When I switched to observable, I noticed a strange behavior of the ViewModel. The ViewModel is created 3x times. And my question is: How to properly initialize the ViewModel via state? Below is a minimal example with log output: ViewModel INIT : EBBB2C41 ViewModel INIT : D8E490DA ViewModel INIT : 54407300 ViewModel DEINIT: D8E490DA @Observable final class ViewModel { @ObservationIgnored let idd: UUID init() { idd = UUID() print("ViewModel INIT : \(idd.uuidString.prefix(8))") } deinit { print("ViewModel DEINIT: \(idd.uuidString.prefix(8))") } } struct SimpleView: View { @Environment(ViewModel.self) private var viewModel var body: some View { @Bindable var viewModel = viewModel Text("SimpleView: \(viewModel.idd.uuidString.prefix(8))") } } struct ContentView: View { @State private var viewModel = ViewModel() var body: some View { SimpleView() .environment(mainViewModel) } }
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436
Feb ’25
Inconsistency Between Translation API Language Identifiers and Foundation Locale
I recently noticed an inconsistency in how languages are represented in Apple’s new Translation API compared to Foundation’s Locale system. Observation from the Translation API When retrieving the list of supported languages using: let availableLanguages = try await LanguageAvailability().supportedLanguages The results are: Language(components: Foundation.Locale.Language.Components(languageCode: Optional(uk), script: nil, region: Optional(UA))) Language(components: Foundation.Locale.Language.Components(languageCode: Optional(zh), script: nil, region: Optional(TW))) Language(components: Foundation.Locale.Language.Components(languageCode: Optional(ko), script: nil, region: Optional(KR))) Language(components: Foundation.Locale.Language.Components(languageCode: Optional(en), script: nil, region: Optional(GB))) Language(components: Foundation.Locale.Language.Components(languageCode: Optional(de), script: nil, region: Optional(DE))) Language(components: Foundation.Locale.Language.Components(languageCode: Optional(zh), script: nil, region: Optional(CN))) Language(components: Foundation.Locale.Language.Components(languageCode: Optional(ja), script: nil, region: Optional(JP))) Language(components: Foundation.Locale.Language.Components(languageCode: Optional(id), script: nil, region: Optional(ID))) Language(components: Foundation.Locale.Language.Components(languageCode: Optional(nl), script: nil, region: Optional(NL))) .... Key points: • The script component is always nil. • Region codes (CN, TW, etc.) determine the script for languages like Chinese (Simplified or Traditional). • Other languages (e.g., en-GB, en-US, pt-BR) also rely on region-based identification. Observation from Foundation Locale (Locale.current.language) When retrieving the user’s system language setting: systemLanguageObj = Locale.current.language I get a different format where the script component is present, but the region may vary based on user settings. This means that mapping between script and region is not consistent between the two APIs, requiring manual handling. My key questions: 1. Is my current approach correct, or is there a better way to get user language settings that match Translation API identifiers? 2. If no alternative exists, could the Translation API align its language identification method with Foundation Locale to reduce ambiguity? Any insights or suggestions would be greatly appreciated!
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343
Feb ’25
TextField .alignmentGuide in Form leading point varies?
I have a Form with a custom TextField which uses a custom Text(). When I use .alignmentGuide on the Text() it seems the origin reference point varies with the length of, but not by the length of, the TextField label String. This is a problem when in a Form. My workaround has been to not use a TextField label but enclose the each TextField in a LabeledContent and then I can set the width of the label and align off of that. How does Form cause TextField to set it's width and why if using .alignmentGuide on Text() does the TextField label length even matter?
Topic: UI Frameworks SubTopic: SwiftUI
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235
Feb ’25
SwiftData Migration Fail: What kind of backing data is this?
I'm trying to test migration between schemas but I cannot get it to work properly. I've never been able to get a complex migration to work properly unfortunately. I've removed a property and added 2 new ones to one of my data models. This is my current plan. enum MigrationV1toV2: SchemaMigrationPlan { static var schemas: [any VersionedSchema.Type] { [SchemaV1.self, SchemaV2.self] } static let migrateV1toV2 = MigrationStage.custom( fromVersion: SchemaV1.self, toVersion: SchemaV2.self, willMigrate: { context in print("Inside will migrate") // Get old months let oldMonths = try context.fetch(FetchDescriptor<SchemaV1.Month>()) print("Number of old months:\(oldMonths.count)") for oldMonth in oldMonths { // Convert to new month let newMonth = Month(name: oldMonth.name, year: oldMonth.year, limit: oldMonth.limit) print("Number of transactions in oldMonth: \(oldMonth.transactions?.count)") print("Number of transactions in newMonth: \(newMonth.transactions?.count)") // Convert transactions for transaction in oldMonth.transactions ?? [] { // Set action and direction let action = getAction(from: transaction) let direction = getDirection(from: transaction) // Update category if necessary var category: TransactionCategory? = nil if let oldCategory = transaction.category { category = TransactionCategory( name: oldCategory.name, color: SchemaV2.Category.Colors.init(rawValue: oldCategory.color?.rawValue ?? "") ?? .blue, icon: getCategoryIcon(oldIcon: oldCategory.icon) ) // Remove old category context.delete(oldCategory) } // Create new let new = Transaction( date: transaction.date, action: action, direction: direction, amount: transaction.amount, note: transaction.note, category: category, month: newMonth ) // Remove old transaction from month oldMonth.transactions?.removeAll(where: { $0.id == transaction.id }) // Delete transaction from context context.delete(transaction) // Add new transaction to new month newMonth.transactions?.append(new) } // Remove old month context.delete(oldMonth) print("After looping through transactions and deleting old month") print("Number of transactions in oldMonth: \(oldMonth.transactions?.count)") print("Number of transactions in newMonth: \(newMonth.transactions?.count)") // Insert new month context.insert(newMonth) print("Inserted new month into context") } // Save try context.save() }, didMigrate: { context in print("In did migrate") let newMonths = try context.fetch(FetchDescriptor<SchemaV2.Month>()) print("Number of new months after migration: \(newMonths.count)") } ) static var stages: [MigrationStage] { [migrateV1toV2] } } It seems to run fine until it gets the the line: try context.save(). At this point it fails with the following line: SwiftData/PersistentModel.swift:726: Fatal error: What kind of backing data is this? SwiftData._KKMDBackingData<Monthly.SchemaV1.Transaction> Anyone know what I can do about this?
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460
Jan ’25
Modifying the native selection menu ios
I am working on a React Native application where I want to modify the native text selection menu (the menu that appears when you long-press on text). Specifically, I want to add a custom option alongside the default ones like Copy, Look Up, Translate, Search Web, and Share. Is there a way to modify the native text selection menu inside a WebView on iOS? How can I add a custom menu option to the default text selection menu while keeping all the default options intact?
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428
Feb ’25
UITabBarController y psoition issue for iOS 18
I am trying to give bottom padding to tabbar i.e ** tabBarFrame.origin.y = view.frame.height - tabBarHeight - 30** but it is not moving up from bottom, it gets sticked to bottom = 0 and the tabbar content moving up taher than tabbar itself.. Code snippet is - `i override func viewDidLayoutSubviews() { super.viewDidLayoutSubviews() let tabBarHeight: CGFloat = 70 // Custom height for the capsule tab bar var tabBarFrame = tabBar.frame tabBarFrame.size.height = tabBarHeight tabBarFrame.size.width = view.frame.width - 40 tabBarFrame.origin.y = view.frame.height - tabBarHeight - 30 tabBarFrame.origin.x = 20 tabBar.frame = tabBarFrame tabBar.layer.cornerRadius = tabBarHeight / 2 tabBar.clipsToBounds = true view.bringSubviewToFront(tabBar) }` Can anyone please help to resolve the issue for iOS 18, it is coming in iOS 18 rest previous versions are fine with the code.
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335
Jan ’25
CoreAutoLayout -[NSISEngine positiveErrorVarForBrokenConstraintWithMarker:errorVar:]
My App always encounter with CoreAutoLayout invade My SnapKit layout constraint as follow: popBgView.snp.makeConstraints { make in make.centerY.equalToSuperview() make.leading.equalTo(assistantTeacherView.snp.trailing).offset(.isiPad ? -50 : -40) if TTLGlobalConstants.isCompactScreen320 { make.width.lessThanOrEqualTo(300) } else { let widthRatio = .isiPad ? 494.0 / 1024.0 : 434.0 / 812.0 make.width.lessThanOrEqualTo(TTLGlobalConstants.screenWidth * widthRatio) } bubbleViewRightConstraint = make.trailing.equalToSuperview().constraint } ..... popBgView.addSubview(functionView) msgLabel.snp.remakeConstraints { make in make.leading.equalToSuperview().inset(Metric.msgLabelHorizantalInset) make.centerY.equalToSuperview() make.trailing.lessThanOrEqualToSuperview().inset(Metric.msgLabelHorizantalInset) make.top.equalTo(Metric.msgLabelVerticalInset) } functionView.snp.makeConstraints { make in make.leading.equalTo(msgLabel.snp.trailing).offset(Metric.msgLabelFunctionSpacing) make.centerY.equalToSuperview() make.trailing.equalToSuperview().offset(-Metric.msgLabelHorizantalInset) } msgLabel and functionView superview is popBgView However, when I try remove from superview for functionView, There is low probability crash: OS Version: iOS 16.1.1 (20B101) Report Version: 104 Exception Type: EXC_BAD_ACCESS (SIGSEGV) Exception Codes: SEGV_NOOP Crashed Thread: 0 Application Specific Information: Exception 1, Code 1, Subcode 14967683541490370463 > KERN_INVALID_ADDRESS at 0xcfb7e4e0f8fe879f. Thread 0 Crashed: 0 CoreAutoLayout 0x382555f44 -[NSISEngine positiveErrorVarForBrokenConstraintWithMarker:errorVar:] 1 CoreAutoLayout 0x382555e9c -[NSISEngine positiveErrorVarForBrokenConstraintWithMarker:errorVar:] 2 CoreAutoLayout 0x3825557e4 -[NSISEngine removeConstraintWithMarker:] 3 CoreAutoLayout 0x382555198 -[NSLayoutConstraint _removeFromEngine:] 4 UIKitCore 0x34d87961c __57-[UIView _switchToLayoutEngine:]_block_invoke 5 CoreAutoLayout 0x382556e8c -[NSISEngine withBehaviors:performModifications:] 6 UIKitCore 0x34d8a1c38 -[UIView(AdditionalLayoutSupport) _switchToLayoutEngine:] 7 UIKitCore 0x34d7f01b0 __57-[UIView _switchToLayoutEngine:]_block_invoke_2 8 UIKitCore 0x34d879770 __57-[UIView _switchToLayoutEngine:]_block_invoke 9 CoreAutoLayout 0x382556e8c -[NSISEngine withBehaviors:performModifications:] 10 UIKitCore 0x34d8a1c38 -[UIView(AdditionalLayoutSupport) _switchToLayoutEngine:] 11 UIKitCore 0x34d8a1848 __45-[UIView _postMovedFromSuperview:]_block_invoke 12 UIKitCore 0x34e7ff8d0 -[UIView _postMovedFromSuperview:] 13 UIKitCore 0x34d85e3c8 __UIViewWasRemovedFromSuperview 14 UIKitCore 0x34d85b1a4 -[UIView(Hierarchy) removeFromSuperview] 15 Collie-iPad 0x203001550 [inlined] InClassAssistantView.functionView.didset (InClassAssistantView.swift:105)
Topic: UI Frameworks SubTopic: UIKit
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245
Jan ’25
A glitch with retained view controllers on Catalyst
Hello! I discovered a bug on Catalyst about a three years ago but it still seems to be not fixed. My bug report number is FB9705748. The Internet is silent on this so I'm even not sure, perhaps it's only me. So to the problem. When you display UICollectionViewController or UIViewController that contains UICollectionView, interact with the collection view then dismiss the view controller, the displayed view controller isn't released if dismissal is done through navigation bar item. The problem occurs only when the run target is My Mac (Mac Catalyst). Everything is fine when you run on iOS or via My Mac (Designed for iPad). The sample project is uploaded to GitHub. It has a video that shows this strange behavior, see the log for 'deinit' messages. I did have some workaround to fix this but it stops to work, presumable on the new macOS. Also, chances are that it's not only UICollectionView which initiates the glitch, it's just that I only encounter it with collection views.
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404
Feb ’25
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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409
Jan ’25
Detect user's tap on status bar
I have an app which uses Scene var body: some Scene { WindowGroup { RootView(root: appDelegate.root) .edgesIgnoringSafeArea(.all) .onOpenURL { url in let stringUrl = url.absoluteString if (stringUrl.starts(with: "http")) { handleUniversalLink(url: stringUrl) } else if (stringUrl.starts(with: "fb")) { let _ = ApplicationDelegate.shared.application( UIApplication.shared, open: url, sourceApplication: nil, annotation: [UIApplication.OpenURLOptionsKey.annotation]) } } } } I need to detect when a user taps on status bar. And call some functions when he does it. Is it possible in Swift?
Topic: UI Frameworks SubTopic: SwiftUI
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248
Feb ’25
Crash when typing Japanese in TextEditor with TextSelection binding.
Environment Mac mini M4 Pro macOS: Version 15.1.1 (24B2091) Xcode: Version 16.1 (16B40) IME: Kotoeri, Google IME Code description struct ContentView: View { @State var text = “” @State var selection: TextSelection? var body: some View { VStack { TextEditor(text: $text, selection: $selection) } .padding() } } Issue Description When built for macOS (not Catalyst, Designed for iPad) and typing “あ” in Japanese input, it crashes. I tried using Kotoeri's Kana input, Kotoeri's Roman input, and Google IME, but the same error occurs and crashes in both cases. There is no issue when using English input. Errors (input method 56222 com.apple.inputmethod.Kotoeri.KanaTyping) (1): Fatal error: String index is out of bounds (input method 56338 com.apple.inputmethod.Kotoeri.RomajiTyping (1): Fatal error: String index is out of bounds Swift/StringUTF16View.swift:368: Fatal error: String index is out of bounds
Topic: UI Frameworks SubTopic: SwiftUI
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360
Jan ’25
Extending iOS screen to an external display
I understand two key concepts from desktop platforms: Screen Mirroring – The same content is displayed on both the primary and external screens. Screen Extension – The external display shows different content that complements what's on the main screen. My question pertains to the second point: Is it possible to extend the display on iOS and iPadOS devices? I'm referring to this Apple documentation, which explains how to extend content from an iOS/iPadOS device to an external display. I tested this in a sample iOS Xcode project. In the iOS Simulator, I was able to detect an "external display" and present a separate UIWindow on it. However, when I tried the same on a real device (iPhone 15 connected to a MacBook Pro via cable), the external display connection was not detected. I’d like to confirm whether screen extension is possible on a real iOS device. From my research, it appears that extension is only supported on iPadOS via Stage Manager, but I want to verify if there’s any way to achieve this on an iPhone. If so, are there any known apps that currently utilize extended display functionality on iOS? If extension is not possible on iOS, what does the documentation mentions iOS?
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546
Feb ’25
iOS Widget can't connect to the host app and shows Skeleton.
Some of our users keep reporting that occasionally some widgets (which initially were working perfectly) are now broken and show only skeletons. Note that the app has multiple widgets, and this happens only to some of them (that is when some widgets get broken, some other widgets are still working normally). While developing the app, I came across this symptom as well, and when I read the device console, I found the following errors in the console (which the system was repeatedly reporting to the console): Unable to get connection interface: Error Domain=LNConnectionErrorDomain Code=1100 "Unable to locate com.example.app.MyAppntents for the com.apple.intents-service extension point" UserInfo={NSLocalizedDescription=Unable to locate com.example.app.MyAppIntents for the com.apple.intents-service extension point} The affected widgets use the 'UserDefaults with groups' to read the data that is stored by the host app. And I think that sometimes the widget fails (or even crashes) while reading the data from the UserDefaults and it ends up showing the skeleton. The only remedy I found was Uninstall the app Reboot the device Install the app again. After this, the widget starts to work again.. So, what can be the reason behind this? Is this an iOS bug or what and how to fight it?
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414
Jan ’25
Start tvOS SideBar Menu Collapsed
I'm trying to make the side bar menu on my tvOS app have the same behavior of Apple's tvOS App. I would like to have the side menu collapsed at the cold start of the app. I'm trying to achieve this by using the defaultFocus view modifier, which should make the button inside the TabView focused at the start of the app. But no matter what I do, the side bar always steels the focus from the inside button. struct ContentView: View { enum Tabs { case viewA case viewB } enum ScreenElements { case button case tab } @FocusState private var focusedElement: ScreenElements? @State private var selectedTab: Tabs? = nil var body: some View { Group { TabView(selection: $selectedTab) { Tab("View A", image: "square", value: .viewA) { Button("View A Button", action: {}) .frame(maxWidth: .infinity, alignment: .center) .focused($focusedElement, equals: .button) } } .tabViewStyle(.sidebarAdaptable) .focused($focusedElement, equals: .tab) } .defaultFocus($focusedElement, .button, priority: .userInitiated) } } Is there a way to start the side bar menu collapsed at the start up of the app?
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392
Jan ’25
looking for sample code 3d wireframe (with lines ) & polygons
Looking for sample code 3d wireframe (with lines ) & polygons and should be able to rotate (set camera angles) I tried sample code seems to be complicated & getting a BLANK screen import SwiftUI import SceneKit struct SceneKitTest2: View { var body: some View { VStack{ Text("SceneKitTest2") SceneView(scene: SCNScene(named:"Earth_1_12756.scn"), options: [.autoenablesDefaultLighting,.allowsCameraControl]) .frame(width:UIScreen.main.bounds.width, height: UIScreen.main.bounds.height/2) Spacer(minLength: 0) } } }
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400
Jan ’25