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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A Summary of the WWDC25 Group Lab - UI Frameworks
At WWDC25 we launched a new type of Lab event for the developer community - Group Labs. A Group Lab is a panel Q&A designed for a large audience of developers. 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 WWDC25 Group Lab for UI Frameworks. How would you recommend developers start adopting the new design? Start by focusing on the foundational structural elements of your application, working from the "top down" or "bottom up" based on your application's hierarchy. These structural changes, like edge-to-edge content and updated navigation and controls, often require corresponding code modifications. As a first step, recompile your application with the new SDK to see what updates are automatically applied, especially if you've been using standard controls. Then, carefully analyze where the new design elements can be applied to your UI, paying particular attention to custom controls or UI that could benefit from a refresh. Address the large structural items first then focus on smaller details is recommended. Will we need to migrate our UI code to Swift and SwiftUI to adopt the new design? No, you will not need to migrate your UI code to Swift and SwiftUI to adopt the new design. The UI frameworks fully support the new design, allowing you to migrate your app with as little effort as possible, especially if you've been using standard controls. The goal is to make it easy to adopt the new design, regardless of your current UI framework, to achieve a cohesive look across the operating system. What was the reason for choosing Liquid Glass over frosted glass, as used in visionOS? The choice of Liquid Glass was driven by the desire to bring content to life. The see-through nature of Liquid Glass enhances this effect. The appearance of Liquid Glass adapts based on its size; larger glass elements look more frosted, which aligns with the design of visionOS, where everything feels larger and benefits from the frosted look. What are best practices for apps that use customized navigation bars? The new design emphasizes behavior and transitions as much as static appearance. Consider whether you truly need a custom navigation bar, or if the system-provided controls can meet your needs. Explore new APIs for subtitles and custom views in navigation bars, designed to support common use cases. If you still require a custom solution, ensure you're respecting safe areas using APIs like SwiftUI's safeAreaInset. When working with Liquid Glass, group related buttons in shared containers to maintain design consistency. Finally, mark glass containers as interactive. For branding, instead of coloring the navigation bar directly, consider incorporating branding colors into the content area behind the Liquid Glass controls. This creates a dynamic effect where the color is visible through the glass and moves with the content as the user scrolls. I want to know why new UI Framework APIs aren’t backward compatible, specifically in SwiftUI? It leads to code with lots of if-else statements. Existing APIs have been updated to work with the new design where possible, ensuring that apps using those APIs will adopt the new design and function on both older and newer operating systems. However, new APIs often depend on deep integration across the framework and graphics stack, making backward compatibility impractical. When using these new APIs, it's important to consider how they fit within the context of the latest OS. The use of if-else statements allows you to maintain compatibility with older systems while taking full advantage of the new APIs and design features on newer systems. If you are using new APIs, it likely means you are implementing something very specific to the new design language. Using conditional code allows you to intentionally create different code paths for the new design versus older operating systems. Prefer to use if #available where appropriate to intentionally adopt new design elements. Are there any Liquid Glass materials in iOS or macOS that are only available as part of dedicated components? Or are all those materials available through new UIKit and AppKit views? Yes, some variations of the Liquid Glass material are exclusively available through dedicated components like sliders, segmented controls, and tab bars. However, the "regular" and "clear" glass materials should satisfy most application requirements. If you encounter situations where these options are insufficient, please file feedback. If I were to create an app today, how should I design it to make it future proof using Liquid Glass? The best approach to future-proof your app is to utilize standard system controls and design your UI to align with the standard system look and feel. Using the framework-provided declarative API generally leads to easier adoption of future design changes, as you're expressing intent rather than specifying pixel-perfect visuals. Pay close attention to the design sessions offered this year, which cover the design motivation behind the Liquid Glass material and best practices for its use. Is it possible to implement your own sidebar on macOS without NSSplitViewController, but still provide the Liquid Glass appearance? While technically possible to create a custom sidebar that approximates the Liquid Glass appearance without using NSSplitViewController, it is not recommended. The system implementation of the sidebar involves significant unseen complexity, including interlayering with scroll edge effects and fullscreen behaviors. NSSplitViewController provides the necessary level of abstraction for the framework to handle these details correctly. Regarding the SceneDelagate and scene based life-cycle, I would like to confirm that AppDelegate is not going away. Also if the above is a correct understanding, is there any advice as to what should, and should not, be moved to the SceneDelegate? UIApplicationDelegate is not going away and still serves a purpose for application-level interactions with the system and managing scenes at a higher level. Move code related to your app's scene or UI into the UISceneDelegate. Remember that adopting scenes doesn't necessarily mean supporting multiple scenes; an app can be scene-based but still support only one scene. Refer to the tech note Migrating to the UIKit scene-based life cycle and the Make your UIKit app more flexible WWDC25 session for more information.
Topic: UI Frameworks SubTopic: General
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651
Jun ’25
Using AsyncStream vs @Observable macro in SwiftUI (AVCam Sample Code)
I want to understand the utility of using AsyncStream when iOS 17 introduced @Observable macro where we can directly observe changes in the value of any variable in the model(& observation tracking can happen even outside SwiftUI view). So if I am observing a continuous stream of values, such as download progress of a file using AsyncStream in a SwiftUI view, the same can be observed in the same SwiftUI view using onChange(of:initial) of download progress (stored as a property in model object). I am looking for benefits, drawbacks, & limitations of both approaches. Specifically, my question is with regards to AVCam sample code by Apple where they observe few states as follows. This is done in CameraModel class which is attached to SwiftUI view. // MARK: - Internal state observations // Set up camera's state observations. private func observeState() { Task { // Await new thumbnails that the media library generates when saving a file. for await thumbnail in mediaLibrary.thumbnails.compactMap({ $0 }) { self.thumbnail = thumbnail } } Task { // Await new capture activity values from the capture service. for await activity in await captureService.$captureActivity.values { if activity.willCapture { // Flash the screen to indicate capture is starting. flashScreen() } else { // Forward the activity to the UI. captureActivity = activity } } } Task { // Await updates to the capabilities that the capture service advertises. for await capabilities in await captureService.$captureCapabilities.values { isHDRVideoSupported = capabilities.isHDRSupported cameraState.isVideoHDRSupported = capabilities.isHDRSupported } } Task { // Await updates to a person's interaction with the Camera Control HUD. for await isShowingFullscreenControls in await captureService.$isShowingFullscreenControls.values { withAnimation { // Prefer showing a minimized UI when capture controls enter a fullscreen appearance. prefersMinimizedUI = isShowingFullscreenControls } } } } If we see the structure CaptureCapabilities, it is a small structure with two Bool members. These changes could have been directly observed by a SwiftUI view. I wonder if there is a specific advantage or reason to use AsyncStream here & continuously iterate over changes in a for loop. /// A structure that represents the capture capabilities of `CaptureService` in /// its current configuration. struct CaptureCapabilities { let isLivePhotoCaptureSupported: Bool let isHDRSupported: Bool init(isLivePhotoCaptureSupported: Bool = false, isHDRSupported: Bool = false) { self.isLivePhotoCaptureSupported = isLivePhotoCaptureSupported self.isHDRSupported = isHDRSupported } static let unknown = CaptureCapabilities() }
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373
Dec ’24
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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219
Jan ’25
Opening recent files from Dock with MacCatalyst app
We are developing an MacOS app from our iOS app using MacCatalyst. If I press long on the app icon on the Dock, a list of recent files appears. If I tap one one of these files nothing happens. I would expect the scene delegate function: func scene(_ scene: UIScene, openURLContexts URLContexts: Set<UIOpenURLContext>) would be called but it is not. Can somebody maybe explain what I am missing here? The list of recent files also appears in the Menu under File > Open recent files. There I can tap on a file and it it is opened correctly using the scene delegate method mentioned above. The files can also be opened with the app using the Finder, so the associated file types with the app are correct.
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301
Jan ’25
AppClip card keeps showing up
After the user clicks the Open button in the AppClip card, the AppClip launches, but the card keeps appearing whenever the user clicks Open. It doesn’t disappear until the user clicks the Close button on the card. This issue started appearing two months ago and only occurs on iOS 17.6 and 17.7. [demo video](https://drive.google.com/file/d/1vJ-7E5JSdO_xoVkDYxBJDkj8sm-dvxv1/view?usp=share_link
Topic: UI Frameworks SubTopic: General
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171
Feb ’25
SwiftUI: How to change `contentInset` of `List`
Hi, Is there any way of changing the contentInset (UIKit variant) of a List in SwiftUI? I do not see any APIs for doing so, the closest I gotten is to use safeAreaInset . While visually that works the UX is broken as you can no longer "scroll" from the gap made by the .safeAreaInset(edge:alignment:spacing:content:) I have subbmited a feedback suggestion: FB16866956
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173
Mar ’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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387
Jan ’25
LazyHstack in SwiftUI not supporting varying height views
In SwiftUI I want to create a list with LazyVstack and each row item in the LazyVstack is a LazyHstack of horizontally scrollable list of images with some description with line limit of 3 and width of every item is fixed to 100 but height of every item is variable as per description text content. But in any of the rows if the first item has image description of 1 line and the remaining items in the same row has image description of 3 lines then the LazyHStack is truncating all the image descriptions in the same row to one line making all the items in that row of same height. Why LazyHStack is not supporting items of varying height ? Expected behaviour should be that height of every LazyHStack should automatically adjust as per item content height. But it seems SwiftUI is not supporting LazyHstack with items of varying height. Will SwiftUI ever support this feature?
Topic: UI Frameworks SubTopic: SwiftUI
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260
Feb ’25
widgetextension Get availableInputs
I want to get the availableInputs list in widgetextension, but it always returns only the phone's microphone. I have confirmed that I have connected additional Bluetooth devices. Why is this? If I want to get the information I want, how should I do it?
Topic: UI Frameworks SubTopic: SwiftUI
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169
Dec ’24
UIDocumentPickerViewController Dismisses Automatically Twice When Selecting Multiple Files Quickly
Description: When using UIDocumentPickerViewController in iOS, if the user taps two or more files in quick succession, the picker view controller dismisses itself automatically twice. This results in an unintended behavior, leading to inconsistent screen states or redundant dismiss animations. Steps to Reproduce: Initialize a UIDocumentPickerViewController instance in UIDocumentPickerModeImport. UIDocumentPickerViewController *documentPicker = [[UIDocumentPickerViewController alloc] initWithDocumentTypes:@[(NSString *)kUTTypeData] inMode:UIDocumentPickerModeImport]; documentPicker.delegate = self; documentPicker.modalPresentationStyle = UIModalPresentationFullScreen; documentPicker.allowsMultipleSelection = NO; [self presentViewController:documentPicker animated:YES completion:nil]; Launch the document picker. Quickly tap two or more files in succession. Expected Behavior: The UIDocumentPickerViewController should dismiss once and call the delegate method documentPicker:didPickDocumentsAtURLs: with the selected file(s). Actual Behavior: The UIDocumentPickerViewController automatically dismisses twice. This issue occurs even when no explicit call to dismissViewControllerAnimated: is made in the delegate method. Observed Results: The didPickDocumentsAtURLs: callback is invoked after the picker is already dismissed. During this process, unintended behavior such as multiple dismiss animations, view controller state corruption, or UI inconsistencies may occur. Impact: This issue disrupts the user experience and causes UI glitches when selecting documents. It prevents developers from having full control over dismiss behavior or mitigating the problem programmatically. Environment: iOS Version: iOS 15.0 and later (also reproduced on iOS 17.4) Device: Reproducible on multiple iPhone and iPad models Framework: UIKit Conclusion: This appears to be a system-level issue with UIDocumentPickerViewController. The automatic dismiss behavior is not correctlyhandling multiple taps, causing unintended dismiss events. Developers have no explicit way to prevent this behavior or gain full control over the dismissal process. We kindly request Apple to investigate and resolve this issue to ensure UIDocumentPickerViewController behaves as expected when interacting with multiple taps.
Topic: UI Frameworks SubTopic: UIKit Tags:
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375
Dec ’24
How do I obtain the preview image for a PDF?
I have a SwiftUI view of the form struct ContentView: View { // ... .onDrop(of: [.pdf], isTargeted: $isDropTargeted) { pdfs in for pdf in pdfs { I'm just not sure what to do next, I see there's a loadPreviewImage() that if I use like: Task.detached { // returns any NSSecureCoding object let image = try! await pdf.loadPreviewImage() } Not sure how I'm supposed to get my preview image from that NSSecureCoding object
Topic: UI Frameworks SubTopic: SwiftUI
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233
Jan ’25
AppIntents - Choosing a default Measurement<UnitMass> for body weight based on locale
Here’s a clearer and more concise version of your question: I’m creating an AppIntent to allow users to log their body weight. My intent includes a @Parameter defined as: @Parameter( title: "Weight", description: "Current Weight", defaultUnit: .pounds, supportsNegativeNumbers: false ) var weight: Measurement<UnitMass> This works but doesn’t respect the user’s Locale and its measurementSystem. When I add defaultUnitAdjustForLocale: true to the @Parameter macro, the default always switches to kilograms, regardless of the locale. How can I correctly set the default unit to match the user’s locale for the purpose of entering a users body weight?
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369
Jan ’25
Correct way to run modal session?
My assumption has always been that [NSApp runModalForWindow:] runs a modal window in NSModalPanelRunLoopMode. However, while -[NSApplication _doModalLoop:peek:] seems to use NSModalPanelRunLoopMode when pulling out the next event to process via nextEventMatchingMask:untilDate:inMode:dequeue:, the current runloop doesn't seem to be running in that mode, so during -[NSApplication(NSEventRouting) sendEvent:] of the modal-specific event, NSRunLoop.currentRunLoop.currentMode returns kCFRunLoopDefaultMode. From what I can tell, this means that any event processing code that e.g. uses [NSTimer addTimer:forMode:] based on the current mode will register a timer that will not fire until the modal session ends. Is this a bug? Or if not, is the correct way to run a modal session something like this? [NSRunLoop.currentRunLoop performInModes:@[NSModalPanelRunLoopMode] block:^{ [NSApp runModalForWindow:window]; }]; [NSRunLoop.currentRunLoop limitDateForMode:NSModalPanelRunLoopMode]; Alternatively, if the mode of the runloop should stay the same, I've seen suggestions to run modal sessions like this: NSModalSession session = [NSApp beginModalSessionForWindow:theWindow]; for (;;) { if ([NSApp runModalSession:session] != NSModalResponseContinue) break; [NSRunLoop.currentRunLoop limitDateForMode:NSModalPanelRunLoopMode]; } [NSApp endModalSession:session]; Which would work around the fact that the timer/callbacks were scheduled in the "wrong" mode. But running NSModalPanelRunLoopMode during a modal session seems a bit scary. Won't that potentially break the modality?
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82
Mar ’25
*** -colorSpaceName not valid
Here is a relatively simple code fragment: let attributedQuote: [NSAttributedString.Key: Any] = [ .font: FieldFont!, .foregroundColor: NSColor.red] let strQuote = NSAttributedString.init(string:"Hello World", attributes:attributedQuote) strQuote.draw(in: Rect1) It compiles without an issue, bur when I execute it, I get: "*** -colorSpaceName not valid for the NSColor <NSColor: 0x6000005adfd0>; need to first convert colorspace." I have tried everything I can think of. What's going on?
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387
Jan ’25
Animation Issue: SwiftUI View Not Animating Height Changes in UIHostingController
Hello, I’m developing an app where I display a SwiftUI view inside a UIHostingController embedded within a UIKit ViewController. I’m trying to animate the height of the UIHostingController’s view based on a switch’s value, but the SwiftUI view doesn’t animate at all. Below is a simplified version of my code: class ViewController: UIViewController { private lazy var parentView: UIView = { let view = UIView() view.backgroundColor = .red view.translatesAutoresizingMaskIntoConstraints = false return view }() private lazy var hostingView: UIView = { let testView = TestView() let hostingController = UIHostingController(rootView: testView) let view = hostingController.view! view.translatesAutoresizingMaskIntoConstraints = false return view }() private lazy var button: UISwitch = { let button = UISwitch() button.addTarget(self, action: #selector(onClickSwitch(sender:)), for: .valueChanged) button.translatesAutoresizingMaskIntoConstraints = false return button }() private var hostingViewHeightConstraint: NSLayoutConstraint? override func viewDidLoad() { super.viewDidLoad() view.addSubview(parentView) parentView.addSubview(hostingView) parentView.addSubview(button) NSLayoutConstraint.activate([ parentView.topAnchor.constraint(equalTo: view.topAnchor), parentView.bottomAnchor.constraint(equalTo: view.bottomAnchor), parentView.leadingAnchor.constraint(equalTo: view.leadingAnchor), parentView.trailingAnchor.constraint(equalTo: view.trailingAnchor) ]) NSLayoutConstraint.activate([ hostingView.bottomAnchor.constraint(equalTo: parentView.bottomAnchor), hostingView.leadingAnchor.constraint(equalTo: parentView.leadingAnchor), hostingView.trailingAnchor.constraint(equalTo: parentView.trailingAnchor) ]) hostingViewHeightConstraint = hostingView.heightAnchor.constraint(equalTo: parentView.heightAnchor, multiplier: 0.5) hostingViewHeightConstraint?.isActive = true NSLayoutConstraint.activate([ button.centerXAnchor.constraint(equalTo: parentView.centerXAnchor), NSLayoutConstraint(item: button, attribute: .centerY, relatedBy: .equal, toItem: parentView, attribute: .centerY, multiplier: 0.25, constant: 0) ]) } @objc func onClickSwitch(sender: UISwitch) { hostingViewHeightConstraint?.isActive = false let multiplier: CGFloat = sender.isOn ? 0.25 : 0.5 hostingViewHeightConstraint = hostingView.heightAnchor.constraint(equalTo: parentView.heightAnchor, multiplier: multiplier) hostingViewHeightConstraint?.isActive = true UIView.animate(withDuration: 0.3) { self.view.layoutIfNeeded() } } } I’m looking for the behavior demonstrated in the video below: Does anyone have suggestions on how to achieve this?
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178
Mar ’25
"Add-on" services no longer supported?
Our MacOS app has for some time been able to create so-called "add-on" services, which are dynamically written to individual bundles in ~/Library/Services/ (as opposed to being statically defined in the app's Info.plist). These worked fine for a long time until recently. They still appear in other app Services menus, but do not get as far as calling the specified instance method in our app. Does anyone know if add-on services are no longer supported? Perhaps due to some new security constraint? The documentation on app services in general seems to be out of date. I did try copying the add-on service definition from the add-on plist into the app's Info.plist. That seemed to work, so the basic specification doesn't seem to have changed.
Topic: UI Frameworks SubTopic: AppKit
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271
Jan ’25
How to override NSWindow in a pure SwiftUI Application
So I am looking to use a custom NSWindow application (so I can implement some enhanced resizing/dragging behavior which is only possible overriding NSWindow). The problem is my whole application is currently SwiftUI-based (see the project here: https://github.com/msdrigg/Roam/blob/50a2a641aa5f2fccb4382e14dbb410c1679d8b0c/Roam/RoamApp.swift). I know there is a way to make this work by dropping my @main SwiftUI app and replacing it with a SwiftUI root view hosted in a standard AppKit root app, but that feels like I'm going backwards. Is there another way to get access (and override) the root NSWindow for a SwiftUI app?
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278
Mar ’25
MacOS Scale to view
on iOS you can choose to scale to view to have the app resize the screen easily in the developer environment. Scale to view is however not easily done on MacOS using NS to solve on MacOS now. Is it possible for the Apple developer team to make this easier for the Developer, as I understand it is for iOS applications?
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261
Feb ’25