I have an iOS app that supports multiple scenes on the iPad, and which has an "Open in Another Window" feature which creates a new window scene. I would like to bring this feature to the iPhone Duo. On the iPhone Duo, of course, creating new windows is only supported when the device is open; when it is closed, creating new windows does not work. (If you try, an error is thrown.) Until now, the way I have checked whether my "Open in Another Window" feature should be available is to check to see if UIApplication.shared.supportsMultipleScenes is true. This has always returned false for previous iPhones and true for iPads. Unfortunately, however, this does not work as expected on the iPhone Duo. On the Duo, I would expect supportsMultipleScenes to return true when the device is open, but false when it is closed. This is not the case: it returns true for all poses. (Filed as #FB24948411 as this doesn't seem right to me.) So it does not help me decide whether the feature should be available. UIWindowScene.ActivationAction does work as expected when used in a menu, with the action auto-hiding when the Duo is in the closed pose. In my app, though, I need more than just an auto-hiding menu item; I need to check whether creating a new window is currently possible for certain UI availability decisions. What, then, is the correct way of checking this, if it's not with supportsMultipleScenes? Given that UIWindowScene.ActivationAction is able to hide itself, I assume there is some better way of checking that I have missed.

Sometime pre-iOS 26 it was possible to use a SplitViewController so that on iPhone you saw the master as a side menu (e.g. hamburger), and the detail full screen. While on iPad you would see the master displayed in a sidebar that could be closed, with the detail fullscreen. This has changed, using a SplitViewController on iPhone now forces you into having 2 fullscreen screens, with a push/pop layout and a back button. In situations where you want the detail screen to open first, this results in users opening the app to find a back button already presented, despite having not navigated anywhere. They must "return" to a screen they never saw. I really despise this layout and find it to be quite a UX issue. But given the new iPhone Duo, using the SplitViewController is now one of the easiest ways to maintain the necessary responsiveness needed, forcing us to accept this behaviour on regular iPhones. Can we PLEASE get the old functionality back, where we can explicitly state on iPhone that the master will always be displayed as a menu?

Environment App built with Xcode 26.3 (iOS 26 SDK) Deployment Target: iOS 16+ Issue occurs only on devices upgraded to iOS 27. Works perfectly on iOS 26.x. Problem description: After end‑user upgrades their iPhone to iOS 27, a persistent stale frosted‑glass / blur rendering effect appears at the top area of screens. This symptom occurs both on native UITableView and inside WKWebView. No blur‑related code (UIVisualEffectView / backdrop‑filter) is added by our application. Layout frames, insets and contentOffset are all correct. Reproduction hints: The issue can be triggered after presenting then dismissing a WKWebView which loads H5 with overlay popup. Rendering state seems to leak to the whole app process. The leftover blur remains until push/pop the view controller. Is this an iOS 27 system bug, or do we need special adaptation for existing apps built with older Xcode 26.3 SDK? What is the proper workaround for apps compiled with Xcode26.3, since liquidGlassEffectEnabled is only available in iOS27 SDK and cannot be accessed in our current build environment.

Tested on iPhone Duo with iOS 27.1 in Xcode 27.1 Beta Presented VC returns .disabled from preferredVerticalBarBehavior. With UISheetPresentationController, the sheet's trailing safe-area inset is removed at all detents (including default medium and large, plus custom detents at various fixed heights). The interesting part: the status bar remains in the vertical bar for detents below UISheetPresentationControllerDetentResolutionContext.maximumDetentValue, but at detents that are greater than or equal to that maximumDetentValue, the status bar moves to the top. With a custom UIPresentationController: Default shouldPresentInFullscreen == true: trailing inset remains, regardless of presented VC's preferredVerticalBarBehavior (possibly expected) With shouldPresentInFullscreen == false: trailing inset is removed, but the status bar moves to the top regardless of the presented view's height. Using automatic as preferredVerticalBarBehavior keeps the status bar on the right, but also keeps the safe-area insets increased. Is UISheetPresentationController applying detent-aware, presentation-scoped vertical bar behavior? Is there a public way for a custom UIPresentationController to remove the sheet's vertical-bar inset while keeping the status bar vertical [until the presentation reaches full height]?

I’m simulating an iPhone Duo using Xcode 27.1 beta, and I’m having trouble tapping buttons placed near the top of the screen. It seems that the top ~20 pixels of the screen are not responding to taps. In my ViewController, preferredScreenEdgesDeferringSystemGestures returns .all, so system gestures should require two swipes to be triggered. However, a simple tap in this area does not seem to be recognized. This appears to happen only on iPhone Duo; taps work normally on other iPhone models. Does anyone know whether this behavior is expected to occur on the actual iPhone Duo hardware as well, or is it specific to the simulator? For reference, the buttons are positioned according to LayoutMarginsGuide with Safe Area. FB24914903 I wonder if anyone knows how to get the top margin size programmatically.

I’m investigating an issue with simultaneous Apple Pencil and finger input on iPad. Apple Pencil + finger input works correctly while the Pencil user’s hand/palm is off the display. However, when drawing naturally with Apple Pencil with the palm resting on the display, an existing finger drawing contact elsewhere on the screen can be cancelled and then stop receiving input for several seconds. Pencil input continues normally throughout. Initially I suspected PencilKit, but I’ve reproduced the underlying behaviour below PencilKit/SwiftUI. Instrumenting UIKit at UIApplication.sendEvent shows the finger touch being cancelled and, in some cases, no further events for that finger for ~4–5 seconds while Pencil MOVED events continue to arrive normally. Everything delivered to the application is accounted for, so this appears to occur before our drawing/rendering code. Is this expected behaviour from the iPad’s Pencil/palm rejection? More specifically: Is there any supported way to tell UIKit that an existing finger contact should remain intentional while Pencil + palm contact is present? Is palm rejection configurable at this level? Is there another public input API we should be using for this scenario? We’re currently testing UIEvent.coalescedTouches(for:) to determine whether additional genuine finger samples are available during these apparent gaps, but haven’t completed that test yet. Any guidance on whether this interaction is expected to be supportable through public UIKit APIs would be appreciated.

Hi,I'm trying to implement undo and redo, in a Custom keyboard extension. However, calling undo() on the UndoManager from UIInputViewController, doesn't seems to work. Is there any other way of getting the UndoManager from the app the keyboard is connected to?Or do I need create my own logic to store what a user has written?

Hi, I've discovered that my Keyboard Extension is unable to detect any hinge status update on iPhone Duo. I tired both UIKit and SwiftUI approach - nothing works. Is there any workaround to make it work? Reproducible demo: https://www.icloud.com/iclouddrive/0460exMJtAdRkpk8EDjb751nw Xcode 27.1 (27A9269) iOS 27.1 beta 1 (24A94401) I also created a bug report: FB24883137

What's the best practices to adopt iPhone Duo for a production UIKit app? What few things we need to consider during the development? "As long as we use auto layout, it should be fine" is this correct term for iPhone Duo? Meaning, as long as our app use proper auto layout, our app should be able to support iPhone Duo properly.

Group Labs are a unique opportunity for the community to submit questions directly to a panel of Apple engineers and designers. Here are the highlights from the iPhone Duo Group Labs: How should apps preserve navigation and UI state when switching between the inner and outer displays? Treat display transitions as size-class and trait changes, not a scene disconnect or app termination; your process stays alive. For more information, see Prepare your app for iPhone Duo. For state that must survive a scene disconnect/reconnect, implement stateRestorationActivity(for:) to save an NSUserActivity Restoring your app's state. Do multiple instances of the same app on iPhone Duo share UserDefaults/@AppStorage state? Multiple instances of your app's UI on iPhone Duo behave similarly to multi-window support on iPadOS. To learn more, see Leverage multiple displays and scenes on iPhone Duo. Both UserDefaults and AppStorage are app-wide, not per-window, stores. If a full-screen app on the inner display is closed, does it move to the outer display or get backgrounded? iPhone Duo honors UIRequiresFullScreen and apps adapt in place as the device opens and closes rather than backgrounding. To learn more, watch Prepare your app for iPhone Duo. How should apps preserve state — text input, scroll position, video playback, camera sessions — during hinge angle transitions? For example, when a LazyVGrid's column count changes because the device folds, does SwiftUI preserve scroll position automatically, or should you use scrollPosition(id:)? The system generally preserves text input and scroll position automatically since hinge angle changes are represented as size-class and trait updates, not a scene disconnect or app termination. This applies even to cases like a LazyVGrid column-count change triggered by opening or closing the device — apps typically don't need to manually manage scroll position with scrollPosition(id:anchor:) for this transition. For more info, see Prepare your app for iPhone Duo. How can apps preserve what someone is doing when switching displays or folding/unfolding? Treat this as a resize/trait-change event, not app teardown — your process keeps running as size classes change. See Prepare your app for iPhone Duo to learn more. For scenes that actually disconnect and reconnect, implement stateRestorationActivity(for:) to save an NSUserActivity Restoring your app's state. How does actively playing video behave through the hinge angle animation? The system generally preserves video playback and player position automatically since hinge angle changes are represented as size-class and trait updates, not a scene disconnect or app termination. AVKit will scale and resize the video automatically. If a user folds or unfolds the device mid-checkout, what does the system preserve automatically, and what should the app manage itself to avoid lost input or duplicate requests? When someone opens or closes an iPhone Duo, the system represents this as a size-class and trait collection change, not a scene disconnect or app teardown, so in-memory state like input fields typically persists automatically since the app’s process keeps running. For more info, see Prepare your app for iPhone Duo. How should apps handle the keyboard and text input when the device folds or unfolds while typing? As iPhone Duo folds or unfolds, the available screen geometry and framing change. Ensure your app adopts standard layout controls, containers, and size classes to handle resizability gracefully across all poses. When a text field becomes first responder, the system automatically shows the keyboard and binds its input to the text field. Because the appearance of the keyboard has the potential to obscure portions of your user interface, you should update your interface as needed to ensure that the text field being edited remains visible. Use keyboard notifications such as keyboardWillShowNotification, keyboardWillHideNotification, and keyboardWillChangeFrameNotification to detect the appearance and disappearance of the keyboard and to make necessary changes to your interface layout. To learn more, see UITextField. If someone is typing and closes iPhone Duo, does the keyboard/editing session survive the hinge transition, or does it get a new scene? When a user types and closes iPhone Duo, the active editing session and keyboard do not get a completely new scene. Instead, the app undergoes a dynamic resizing and transitions from the inner display to the compact outer display, maintaining the existing scene and application state. For more info, watch Prepare your app for iPhone Duo.

I’m adapting a UIKit app for iPhone Duo and noticed that UITableViewController separators extend underneath the navigation and tab bar controls when those controls move to the side. The cell content appears to respect the safe area, but the separators continue to the screen edge. When using a UITableView inside a regular UIViewController, constraining its horizontal edges to the parent’s safeAreaLayoutGuide prevents this. With UITableViewController, however, the table view is the controller’s root view. The attached screenshots show the difference: Screenshot 1: Separators extend underneath the side controls. Screenshot 2: Separators stop at the safe area boundary. Should UITableViewController respect these safe area boundaries out of the box, including for separators, when system controls move to the side? Or is drawing separators underneath those controls the intended behavior? If automatic adaptation is expected, could this be a UIKit issue?

I just downloaded Xcode 27.1 to test out the iPhone Duo simulator, and I notice that UIAlertController.addTextField, which was working fine in 27, is now very broken, resulting in a text field that is squashed vertically and pushed over to the right in the alert sheet. This is very easy to reproduce - the following code will show the problem if you build in Xcode 27.1 and run on iOS 27.1 or iOS 27.2: let alert = UIAlertController(title: "Create Something", message: "Enter a title.", preferredStyle: .alert) alert.addTextField { textField in textField.placeholder = "Title" } alert.addAction(UIAlertAction(title: "Cancel", style: .cancel)) present(alert, animated: true) The bug isn't limited to the Duo, but can also be seen on an iPad (and probably a regular phone). I would post a screenshot, but the last time I tried that, the forum software erroneously banned me for two weeks. I have reported this as bug #FB24889500, but given that we use alerts with text fields for users adding new items to the outline in our app, something the user does a lot, I'm wondering if there is a workaround, since this is going to make our app look very buggy.

Hi everyone, We are validating our existing legacy UIKit application on iPhone Duo, built using Xcode26 and the iOS26 SDK. Our app follows the classic AppDelegate‑only pattern. We do not adopt UIApplicationSceneManifest or SceneDelegate, so it runs under the system’s legacy compatibility container window. The codebase still heavily uses UIScreen.main, and we have not yet adopted UIWindowScene. Full scene‑based migration is planned for Xcode27, but we need to ship builds with Xcode26 for now and expect reasonable compatibility on iPhone Duo hardware. Most of our application UI displays correctly inside this system‑provided compatibility window. However we noticed a critical positioning defect for system‑owned permission alerts. System‑rendered authorization dialogs (push notification permission, photo library access, location permission — these are drawn by the system process, not our app) are positioned relative to the full physical inner display of iPhone Duo. Instead of centering within our app’s compatibility‑mode container viewport, these permission pop‑ups appear offset and misaligned against our app’s visible window bounds. I have three key questions: Is this mis‑positioning of system permission alerts expected documented behavior for non‑Scene, AppDelegate‑only legacy apps running inside compatibility mode on iPhone Duo when built with Xcode26 SDK? While we remain on Xcode26 SDK, before completing full scene‑based lifecycle migration for Xcode27: are there any known workarounds to correct or mitigate this system permission alert offset issue? Or is this a hard limitation of the legacy compatibility mode in Xcode26, meaning we cannot fix it until we fully migrate to scene‑based app lifecycle? If this is intended limitation, could anyone point me to official Apple documentation that covers this exact behavior for legacy apps on iPhone Duo? Thanks for any insight.

Environment Xcode 27.1 iOS 27.1 iPhone Duo simulator UIKit app built with the iOS 27.1 SDK Issue On iPhone Duo, the background of a system-managed UINavigationBar does not extend completely to the top edge of the window. The navigation bar is configured using UINavigationBarAppearance with an opaque blue background. However, a horizontal white strip remains above the blue navigation bar. I also post a feedback: FB24859353 Questions Is this expected behavior on iPhone Duo? What is the recommended way to style this top region? Should apps add a custom background underlay outside the UINavigationBar bounds? Could this be an iOS 27.1 or iPhone Duo simulator issue? Minimal reproduction code: import UIKit final class DemoTabBarController: UITabBarController { override func viewDidLoad() { super.viewDidLoad() viewControllers = NavigationBarStyle.allCases.map { style in let content = DiagnosticsViewController(style: style) let navigationController = UINavigationController(rootViewController: content) navigationController.tabBarItem = UITabBarItem( title: style.title, image: UIImage(systemName: style.symbolName), selectedImage: nil ) style.apply(to: navigationController.navigationBar) return navigationController } } } enum NavigationBarStyle: CaseIterable { case systemDefault case appearance case legacy var title: String { switch self { case .systemDefault: return "Default" case .appearance: return "Appearance" case .legacy: return "Legacy" } } var symbolName: String { switch self { case .systemDefault: return "iphone" case .appearance: return "paintbrush" case .legacy: return "clock.arrow.circlepath" } } func apply(to navigationBar: UINavigationBar) { switch self { case .systemDefault: break case .appearance: let appearance = UINavigationBarAppearance() appearance.configureWithOpaqueBackground() appearance.backgroundColor = .demoBlue appearance.shadowColor = nil appearance.titleTextAttributes = [.foregroundColor: UIColor.white] navigationBar.tintColor = .white navigationBar.standardAppearance = appearance navigationBar.compactAppearance = appearance navigationBar.scrollEdgeAppearance = appearance case .legacy: navigationBar.tintColor = .white navigationBar.barTintColor = .demoBlue navigationBar.backgroundColor = .demoBlue navigationBar.setBackgroundImage(Self.solidImage(color: .demoBlue), for: .default) navigationBar.shadowImage = UIImage() navigationBar.isTranslucent = false navigationBar.titleTextAttributes = [.foregroundColor: UIColor.white] } } private static func solidImage(color: UIColor) -> UIImage { return UIGraphicsImageRenderer(size: CGSize(width: 1, height: 1)).image { context in color.setFill() context.fill(CGRect(x: 0, y: 0, width: 1, height: 1)) } } } private extension UIColor { static let demoBlue = UIColor(red: 0.0, green: 0.46, blue: 0.70, alpha: 1.0) }

I have an App where I use the UISheetPresentationController to present a menu as a "drawer" (like the "FindMy" or "Maps") App. Because the sheet is presented over a map, I made the sheet semi-transparent/blurry, so the Map shines through, which looks nice. The sheet is using a UITableView with the "insetGroup" style, so the table cells have the nice rounded borders and there are margins to the sheet borders. When running the App on the iPhone Duo (Simulator) on the outer display, the tableView does no longer respect the "insetGroup" style, it is rendered like it would have the "plain" style, which destroys everything that look good. No rounded borders, no margins. However if I opt-out of the automatic "vertical toolbar behavior" (overriding preferredVerticalBarBehavior so it returns "disabled"), then everything looks great again, however then the sheet content might overlap with the sidebar icons and camera because it now covers the whole area up to the right screen border. Is this supposed to be this way (if yes, why?), is there a way to fix this, or do we have to wait for a bugfix within iOS 27.1? The tableview still claims to have the "insetGrouped" style, just it does not render this way. I did not see any similar issues under other circumstances. Only UISheetPresentationController seems to be affected by this. Is there a way to correctly detect if the App is running on an iPhone Duo, so we could use this detection to add workarounds for such issues?

Description: When wrapping a UIKit UIScrollView in SwiftUI via UIViewControllerRepresentable, applying topEdgeEffect.style = .hard, then using .toolbar() and .ignoresSafeArea(.container) on the SwiftUI view causes an incorrect/truncated initial height of Navigation Bar on first load. The height will refresh to the correct value after backgrounding the app or switching tabs. Steps to Reproduce: Wrap a UICollectionViewController in UIViewControllerRepresentable. Set collectionView.topEdgeEffect.style = .hard. Embed it in a SwiftUI NavigationStack and apply .toolbar() and .ignoresSafeArea() Happens on Xcode 26.x and iOS 26.x (untested on 27s).

[Submitted as FB21958289] A minimal SwiftUI app logs framework warnings when a bottom bar Menu is used with the system search toolbar item. The most severe issue is logged as a console Fault (full logs below): Adding 'UIKitToolbar' as a subview of UIHostingController.view is not supported and may result in a broken view hierarchy. Add your view above UIHostingController.view in a common superview or insert it into your SwiftUI content in a UIViewRepresentable instead. This appears to be a framework-level SwiftUI/UIKit integration issue, not custom UIKit embedding in app code. The UI may still render, but the warnings indicate an internal hierarchy/layout conflict. This occurs in simulator and physical device. REPRO STEPS Create a new project then replace ContentView with the code below. Run the app. The view uses NavigationStack + .searchable + .toolbar with: ToolbarItem(placement: .bottomBar) containing a Menu DefaultToolbarItem(kind: .search, placement: .bottomBar) EXPECTED RESULT No view hierarchy or Auto Layout warnings in the console. ACTUAL RESULT Console logs warnings such as: "Adding 'UIKitToolbar' as a subview of UIHostingController.view is not supported..." "Ignoring searchBarPlacementBarButtonItem because its vending navigation item does not match the view controller's..." "Unable to simultaneously satisfy constraints..." (ButtonWrapper/UIButtonBarButton width and trailing constraints) MINIMAL REPRO CODE import SwiftUI struct ContentView: View { @State private var searchText = "" @State private var isSearchPresented = false var body: some View { NavigationStack { List(0..<30, id: \.self) { index in Text("Row \(index)") } .navigationTitle("Toolbar Repro") .searchable(text: $searchText, isPresented: $isSearchPresented) .toolbar { ToolbarItem(placement: .bottomBar) { Menu { Button("Action 1") { } Button("Action 2") { } } label: { Label("Actions", systemImage: "ellipsis.circle") } } DefaultToolbarItem(kind: .search, placement: .bottomBar) } } } } CONSOLE LOG Adding 'UIKitToolbar' as a subview of UIHostingController.view is not supported and may result in a broken view hierarchy. Add your view above UIHostingController.view in a common superview or insert it into your SwiftUI content in a UIViewRepresentable instead. Ignoring searchBarPlacementBarButtonItem because its vending navigation item does not match the view controller's. view controller: <_TtGC7SwiftUI32NavigationStackHostingControllerVS_7AnyView_: 0x106014c00>; vc's navigationItem = <UINavigationItem: 0x105530320> title='Toolbar Repro' style=navigator searchController=0x106131200 SearchBarHidesWhenScrolling-default; vending navigation item <UINavigationItem: 0x106db4270> style=navigator searchController=0x106131200 SearchBarHidesWhenScrolling-explicit Unable to simultaneously satisfy constraints. Probably at least one of the constraints in the following list is one you don't want. Try this: (1) look at each constraint and try to figure out which you don't expect; (2) find the code that added the unwanted constraint or constraints and fix it. ( "<NSLayoutConstraint:0x600002171450 _TtC5UIKitP33_DDE14AA6B49FCAFC5A54255A118E1D8713ButtonWrapper:0x106a31fe0.width == _UIButtonBarButton:0x106dc4010.width (active)>", "<NSLayoutConstraint:0x6000021558b0 'IB_Leading_Leading' H:|-(8)-[_UIModernBarButton:0x106a38010] (active, names: '|':_UIButtonBarButton:0x106dc4010 )>", "<NSLayoutConstraint:0x600002170eb0 'IB_Trailing_Trailing' H:[_UIModernBarButton:0x106a38010]-(8)-| (active, names: '|':_UIButtonBarButton:0x106dc4010 )>", "<NSLayoutConstraint:0x60000210aa80 'UIView-Encapsulated-Layout-Width' _TtC5UIKitP33_DDE14AA6B49FCAFC5A54255A118E1D8713ButtonWrapper:0x106a31fe0.width == 0 (active)>" ) Will attempt to recover by breaking constraint <NSLayoutConstraint:0x600002170eb0 'IB_Trailing_Trailing' H:[_UIModernBarButton:0x106a38010]-(8)-| (active, names: '|':_UIButtonBarButton:0x106dc4010 )> Make a symbolic breakpoint at UIViewAlertForUnsatisfiableConstraints to catch this in the debugger. The methods in the UIConstraintBasedLayoutDebugging category on UIView listed in <UIKitCore/UIView.h> may also be helpful. Failed to send CA Event for app launch measurements for ca_event_type: 0 event_name: com.apple.app_launch_measurement.FirstFramePresentationMetric Failed to send CA Event for app launch measurements for ca_event_type: 1 event_name: com.apple.app_launch_measurement.ExtendedLaunchMetrics

Hi, We are testing our legacy UIKit app on iPhone Duo, built with Xcode26 / iOS26 SDK. Important background: Our app is pure AppDelegate‑only, we do NOT adopt UIApplicationSceneManifest / SceneDelegate, runs in legacy compatibility mode. Codebase heavily uses UIScreen.main everywhere, no UIWindowScene adoption yet. We are in progress to adopt full iPhone Duo compatibility with Xcode27. For now, we need to ship builds using Xcode26 SDK and expect reasonable compatibility on iPhone Duo hardware. The system already provides legacy compatibility container window for our app. Most of our app UI renders correctly inside the system compatibility window on iPhone Duo. Problems we observed under Xcode26 build on iPhone Duo: System‑rendered permission alerts (push‑notification permission, photo library, location authorization dialog, drawn by system process) are centered relative to the full physical inner display, NOT centered inside our app’s compatibility‑mode window. The alert position is mis‑aligned with our app viewport. The system UINavigationBar layout offset issue: When running inside legacy compatibility window, system‑provided UINavigationBar calculates its top position against full physical screen safe‑area instead of the app compatibility container’s safe‑area. As a result, navigation bar appears too close to the top edge, mis‑aligned with the actual status‑bar area inside our app window. My questions: Are above two issues (system permission alert mis‑position, UINavigationBar safe‑area offset) the expected defined behavior for legacy non‑Scene apps running in compatibility mode on iPhone Duo when built with Xcode26 SDK? When staying on Xcode26 SDK (before we complete Xcode27 & scene‑based lifecycle migration): Is there any workaround we can apply to mitigate these two issues? Or are these limitations unavoidable under Xcode26 / legacy compatibility mode and we can only accept current behavior until we fully migrate to scene‑based lifecycle? 3. If these are expected limitations: is there any official documentation that explicitly describes these behaviours for legacy apps on iPhone Duo? Thank you.

On the iPhone Duo the standard "Edit" button for navigation bars is a text-based button, and text-based buttons are not pushed to the vertical toolbars on the Duo. This looks sometimes silly, if it is the only remaining button that can not be placed in the vertical toolbar and which has the result that an almost empty horizontal navigation bar must be kept visible as well. So I guess it would be good idea to have an icon-based replacement for the Editor button to avoid having two toolbars on the Duo. Is there a best practice for the icon to pick for such an edit button? Would be "square.and.pencil" (SF Symbols) a good choice? Or better the "pencil .circle", because the "square" one is often used for text-based input? Anything better?

Thank you very much for your detailed response and valuable recommendations. At this stage, our application is still built using Xcode 26 and the iOS 26 SDK. Our primary priority right now is to validate runtime behavior for our existing binary running on iPhone Duo. We fully understand that full‑featured support for iPhone Duo requires Xcode 27 plus Scene lifecycle adoption, and we plan to implement those adaptations incrementally in future releases. What we want to clarify specifically: aside from the expected black bars introduced by system compatibility mode, do our existing patterns raise functional bugs or layout risks on iPhone Duo when built with Xcode 26? The legacy patterns we are concerned about are: Window creation via init(frame:), where frame is derived from UIScreen.main.bounds, without adopting SceneDelegate lifecycle. Manual non‑AutoLayout layouts that read UIScreen.main.bounds directly to obtain view width. Whether viewWillTransitionToSize:withTransitionCoordinator: will still fire on fold/unfold state changes under this Xcode‑26‑built compatibility mode. We would like to distinguish which of these usages must be fixed even for our Xcode‑26‑built release, versus which ones are safely handled by system compatibility and can remain unchanged for the time being. We are trying to decide whether urgent compatibility patches are required for our current Xcode 26 build. Thank you again for your support.