Provide views, controls, and layout structures for declaring your app's user interface using SwiftUI.

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SwiftUI 'List' performance issue on macOS
Hi, When using SwiftUI ‘List’ with a large number of elements (4000+), I noticed a significant performance issue if extracting the views inside the ‘ForEach’ block into their own subview class. It affects scrolling performance, and using the scroll handle in the scrollbar causes stutters and beachballs. This seems to happen on macOS only ... the same project works fine on iOS. Here's an example of what I mean: List (selection: $multiSelectedContacts) { ForEach(items) { item in // 1. this subview is the problem ... replace it with the contents of the subview, and it works fine PlainContentItemView(item: item) // 2. Uncomment this part for it to work fine (and comment out PlainContentItemView above) /*HStack { if let timestamp = item.timestamp, let itemNumber = item.itemNumber { Text("\(itemNumber) - \(timestamp, formatter: itemFormatter)") } }*/ } } struct PlainContentItemView: View { let item: Item var body: some View { HStack { if let timestamp = item.timestamp, let itemNumber = item.itemNumber { Text("\(itemNumber) - \(timestamp, formatter: itemFormatter)") } } } } Item is a NSManagedObject subclass, and conforms to Identifiable by using the objectID string value. With this, scrolling up and down using the scrolling handle, causes stuttering scrolling and can beachball on my machine (MacBook Pro M1). If I comment out the ‘PlainContentItemView’ and just use the HStack directly (which is what was extracted to ‘PlainContentItemView’), the performance noticeably improves, and I can scroll up and down smoothly. Is this just a bug with SwiftUI, and/or can I do something to improve this?
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Preventing Swipe-to-Dismiss on SwiftUI Sheets no longer working in iOS 18.1 (22B83)
The interactiveDismissDisabled() function in SwiftUI's Sheet no longer works as expected in iOS 18.1 (22B83). It was working as expected until iOS 18.0.1. Are there any other users experiencing the same issue? struct ContentView: View { @State private var openSheet = false var body: some View { NavigationStack { Button("Open") { openSheet = true } .sheet(isPresented: $openSheet) { SheetView() } } } } struct SheetView: View { @Environment(\.dismiss) private var dismiss var body: some View { NavigationStack { Text("This is the Sheet") .toolbar { ToolbarItem(placement: .cancellationAction) { Button("Cancel") { dismiss() } } } .interactiveDismissDisabled() } } } Supplementary information: In iOS 18.1, even Apple's native Journal app allows users to swipe-to-dismiss the sheet when creating a new entry. Previously, a confirmation dialog would be displayed, but this is no longer the case.​​​​​​​​​​​​​​​​
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iOS18.1 Issue SwiftUI’s App
The interactiveDismissDisabled() function in SwiftUI's Sheet no longer works as expected in iOS 18.1 (22B83). It was working as expected until iOS 18.0.1. Are there any other users experiencing the same issue? struct ContentView: View { @State private var openSheet = false var body: some View { NavigationStack { Button("Open") { openSheet = true } .sheet(isPresented: $openSheet) { SheetView() } } } } struct SheetView: View { @Environment(\.dismiss) private var dismiss var body: some View { NavigationStack { Text("This is the Sheet") .toolbar { ToolbarItem(placement: .cancellationAction) { Button("Cancel") { dismiss() } } } .interactiveDismissDisabled() } } } Supplementary information: In iOS 18.1, even Apple's native Journal app allows users to swipe-to-dismiss the sheet when creating a new entry. Previously, a confirmation dialog would be displayed, but this is no longer the case.​​​​​​​​​​​​​​​​
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Type Eraser for Container
Hi all, Is this allowed: environment(\.container, MyContainer() as Any) While injecting Model container into the environment we use Type . Is there any universal injection type that can inject container as set of any types rather than array similar to navigationPath() type-eraser ?
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How would you make a View that magnifies the View(s) beneath it?
I need a magnifying glass function for one of my SwiftUI Views, but can't find a way to implement it as needed. I found a Youtube video where the author renders the view twice, overlaying the second over the first, then scaling and masking it to create the illusion of magnification, but this is expensive and doesn't work in many cases where more complex views are presented (e.g. a LazyVGrid). I've also explored continually capturing partial screenshots and scaling them up to create the illusion of magnification, but there's no straightforward way to achieve this with SwiftUI without getting into the messiness of UIViewRepresentables. Any help would be greatly appreciated
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SizeClasses, really?
I have an app with looks at the @Environment(\.horizontalSizeClass) variable and it's mate vertical. On the iPhone 16 sim, if I'm in portrait orientation, It says my vertical class is .regular and horizontal is .compact. If I rotate to landscape, it says vertical is now compact, and horizontal is still compact. That seems inconsistent. I'm trying to wrap my head around designing for size class, how am I supposed to think about this? What I want is two areas of the screen: The main area, which shows a graphic, and a much smaller control and data area, which has a button or two and a very narrow text display, which in my current app counts from 1 to 4. The button area These areas ought never move from where they are, but their contents ought to rotate in place to reflect the orientation. If portrait, the button area is on the bottom, if landscapeLeft, the button are is to the right, if landscapeRight, the button area is to the left. This currently sort of works if I test for the max of height or width from a Geometry Reader, but it doesn't handle landscapeRight or portraitUpsideDown correctly.
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I can’t understand this SwiftUI compile error.
Text("Sample Text with wrong font type") .font(.bold) I know this code is incorrect, and it returns an error stating that .font doesn’t have a .bold type. However, when I place this incorrect code within a stack… …no error message appears. Instead, I get: The compiler is unable to type-check this expression in reasonable time; try breaking up the expression into distinct sub-expressions when trying to run the code. It’s unclear why the compiler doesn’t specify that the issue originates from .font(.bold). This was confusing, and I spent 20 minutes figuring out it was a typo.
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SwiftUI TabView lifecycle is weird
I tested the life cycle of TabView and its sub-Views through the demo and found something strange. Please help analyze it. Thank you. The demo project is here https://feedbackassistant.apple.com/feedback/15629780 Operation steps: Step 1: launch app Step 2: click Login button the below log is correct SettingsViewModel init HomeViewModel init HomeView appear Step 3: click Settings tab SettingsView appear (correct) Step 4: click Refresh TabView button the below log is incorrect Refresh TabView StatusViewModel init AccountViewModel init StatusViewModel init (weird) AccountViewModel init (weird) HomeView appear (weird) StatusViewModel deinit AccountViewModel deinit AccountView appear SettingsViewModel deinit HomeViewModel deinit Expect log: Refresh TabView SettingsViewModel deinit HomeViewModel deinit StatusViewModel init AccountViewModel init AccountView appear
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SwiftUI Previews creating views out of thin air?
My iOS (iPhone/iPad/Mac Catalyst) app has a relatively complex authentication flow, primarily required due to it being an API client. Several of my views have .task modifiers that begin executing code when the views are created. After moving to iOS 18 and Xcode 16, when running in the Simulator, I began noticing my workflow was breaking as views were being created out of sequence... but not by me 🤯 Here is an example stack when I place a breakpoint inside of this view's .task. From my logging (and this stack) I can verify I am not creating this view. This view has no preview associated with it, and there are no previews up the view hierarchy from it either. This happens in the Simulator only The only clue I have to go on is this line of text which is present at the top of what looks like ASM when I click on the (5) line in the stack above. SwiftUI`(1) await resume partial function for dispatch thunk of static SwiftUI.PreviewModifier.makeSharedContext() async throws -> τ_0_0.Context: If this (or any hierarchical view) used Previews, I'd remove them to see if it had an effect, but they don't! I'm at a loss on what to do here...
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'Save to Files' doesn't work with ShareLink with FileRepresentation
I want to use ShareLink+FileRepresentation to save a small text file to my iPhone with the steps below. Tap [Share...] to display the share sheet. This sheet contains [Save to Files]. Tap [Save to Files]. A black sheet is displayed, but it disappears instantly. In step 3, I was expecting a browser to be displayed to select the location where the file will be saved. But in fact, a black sheet appears, which quickly disappears. The implemented code is as follows. import SwiftUI @main struct SLSandboxApp: App { var body: some Scene { WindowGroup { let title = Text("File Output") let numListString = "123,456,789" let numListFileName = "numlist.csv" let tagListFile = TextFile(content: numListString, filename: numListFileName) ShareView(title: title, fileToShare: tagListFile, messageToPreview: numListFileName) } } } struct ShareView: View { let title: Text let fileToShare: TextFile let messageToPreview: String var body: some View { ShareLink(item: self.fileToShare, preview: SharePreview(self.messageToPreview)) } } struct TextFile: Transferable { let content: String let filename: String static var transferRepresentation: some TransferRepresentation { FileRepresentation(exportedContentType: .data) { textFile in let data = textFile.content.data(using: .utf8) ?? Data() let tempDirectory = FileManager.default.temporaryDirectory let fileURL = tempDirectory.appendingPathComponent(textFile.filename) try data.write(to: fileURL) return SentTransferredFile(fileURL) } } } The development environment is as follows. Xcode 15.4 (Deployment Target = iOS Deployment Target 17.5) macOS 14.6.1 The execution environment is as follows. iPhone SE Gen3 17.7 The following is a console log from the time the application was launched to the time when the share sheet was displayed by tapping [Share...]. Error acquiring assertion: <Error Domain=RBSServiceErrorDomain Code=1 "(originator doesn't have entitlement com.apple.runningboard.primitiveattribute AND originator doesn't have entitlement com.apple.runningboard.assertions.frontboard AND target is not running or doesn't have entitlement com.apple.runningboard.trustedtarget AND Target not hosted by originator)" UserInfo={NSLocalizedFailureReason=(originator doesn't have entitlement com.apple.runningboard.primitiveattribute AND originator doesn't have entitlement com.apple.runningboard.assertions.frontboard AND target is not running or doesn't have entitlement com.apple.runningboard.trustedtarget AND Target not hosted by originator)}> (501) personaAttributesForPersonaType for type:0 failed with error Error Domain=NSCocoaErrorDomain Code=4099 "The connection to service named com.apple.mobile.usermanagerd.xpc was invalidated: failed at lookup with error 159 - Sandbox restriction." UserInfo={NSDebugDescription=The connection to service named com.apple.mobile.usermanagerd.xpc was invalidated: failed at lookup with error 159 - Sandbox restriction.} Received port for identifier response: <(null)> with error:Error Domain=RBSServiceErrorDomain Code=1 "Client not entitled" UserInfo={RBSEntitlement=com.apple.runningboard.process-state, NSLocalizedFailureReason=Client not entitled, RBSPermanent=false} elapsedCPUTimeForFrontBoard couldn't generate a task port Received port for identifier response: <(null)> with error:Error Domain=RBSServiceErrorDomain Code=1 "Client not entitled" UserInfo={RBSEntitlement=com.apple.runningboard.process-state, NSLocalizedFailureReason=Client not entitled, RBSPermanent=false} elapsedCPUTimeForFrontBoard couldn't generate a task port Received port for identifier response: <(null)> with error:Error Domain=RBSServiceErrorDomain Code=1 "Client not entitled" UserInfo={RBSEntitlement=com.apple.runningboard.process-state, NSLocalizedFailureReason=Client not entitled, RBSPermanent=false} elapsedCPUTimeForFrontBoard couldn't generate a task port The following is the console log that was written when I tapped [Save to file] on the share sheet. cancelled request - error: The operation couldn’t be completed. Invalid argument What modifications should I make to the code to get the expected result?
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MapKit in List Breaks Top/Bottom Bar FadeIn/Out Effect
I've encountered a weird issue with the new Map for iOS 17. In my list, which includes a MapView among other elements, I've observed that with the new initializer, the top and bottom bars are persistently displayed. They don't hide and only appear when scrolling, as they should. This problem doesn't occur with the old, now-deprecated initializer. To illustrate this, I have two screenshots: one with the map enabled and the other with the map disabled, demonstrating the issue. Here is also my new Map code: struct MapListRowView: View { @Binding internal var location: LocationModel @State internal var user: Bool = true private var position: CLLocationCoordinate2D { .init(latitude: location.latitude, longitude: location.longitude) } private var isPad: Bool { UIDevice.current.userInterfaceIdiom == .pad ? true : false } var body: some View { Map(bounds: .init(minimumDistance: 1250)) { if user { UserAnnotation() } Annotation("", coordinate: position) { ZStack { Circle().fill().foregroundColor(.white).padding(1) Image(systemName: "mappin.circle.fill") .resizable() .foregroundColor(.indigo) }.frame(width: 20, height: 20).opacity(user ? .zero : 1.0) } } .frame(height: isPad ? 200 : 100) .cornerRadius(8) .listRowInsets(.init(top: -5, leading: .zero, bottom: -5, trailing: .zero)) .padding(.vertical, 5) .disabled(true) } }
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Nov ’23
Issues with List selection in Sequoia (SwiftUI)
In one of my applications I use several List views with Sections. After upgrading to Sequoia I faced the issue, that after selecting an item, the List suddenly scrolls to a different position. Sometimes the selection even gets out of the view, but in every case a double click just went to the wrong item. At one list I found out, that the issue could be solved after changing the data source. I used a computed property, what seems to be a stupid idea. After changing this it now works. Unfortunately there is another List, where this didn't bring the solution. And unfortunately, I cannot reproduce the issue in a code example. One guess of mine is, that it could be related to the fact, that the rows have different heights (because in some are two lines of text and in some are three). And it seems to happen only in very long lists. It worked perfectly in Sonoma. Does anyone face the same issue?
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Sep ’24
visionOS - Positioning and sizing windows
Hi, In the visionOS documentation Positioning and sizing windows - Specify initial window position In visionOS, the system places new windows directly in front of people, where they happen to be gazing at the moment the window opens. Positioning and sizing windows - Specify window resizability In visionOS, the system enforces a standard minimum and maximum size for all windows, regardless of the content they contain. The first thing I don't understand is why it talk about macOS in visionOS documentation. The second thing, what is this page for if it's just to tell us that on visionOS we have no control over the position and size of 2D windows. Whereas it is precisely the opposite that would be interesting. I don't understand this limitation. It limits so much the use of 2D windows under visionOS. I really hope that this limitation will disappear in future betas.
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Jul ’23
How to build a top/bottom split view with a dynamically-sized divider?
Is there a way to structure three views vertically with a top, middle divider, and bottom view, where the… Middle divider view “hugs” its contents vertically (grows and shrinks based on height of child views) Top and bottom views fill the space available above and below the divider Divider can be dragged all the way up (or down), to completely hide the top view (or bottom view) I’ve been working on this for a while and still can’t get it quite right. The code below is close, but the parent view’s bottom edge shifts when the divider resizes. As a result, the bottom view shifts upward when the divider shrinks, whereas I want it to continue to fill the space to the bottom of the screen. import SwiftUI struct ContentView: View { @State private var topRatio: CGFloat = 0.5 @State private var dividerHeight: CGFloat = 44 var body: some View { GeometryReader { geometry in let topInset = geometry.safeAreaInsets.top let bottomInset = geometry.safeAreaInsets.bottom let totalHeight = geometry.size.height let availableHeight = max(totalHeight - bottomInset - dividerHeight, 0) VStack(spacing: 0) { TopView() .frame(height: max(availableHeight * topRatio - topInset, 0)) .frame(maxWidth: .infinity) .background(Color.red.opacity(0.3)) DividerView() .background(GeometryReader { proxy in Color.clear.preference(key: DividerHeightKey.self, value: proxy.size.height) }) .onPreferenceChange(DividerHeightKey.self) { height in dividerHeight = height } .gesture( DragGesture() .onChanged { value in let maxDragDistance = availableHeight + dividerHeight let translation = value.translation.height / max(maxDragDistance, 1) let newTopRatio = topRatio + translation topRatio = min(max(newTopRatio, 0), 1) } ) .zIndex(1) BottomView() .frame(height: max(availableHeight * (1 - topRatio), 0)) .frame(maxWidth: .infinity) .background(Color.green.opacity(0.3)) } } } } struct DividerHeightKey: PreferenceKey { static var defaultValue: CGFloat = 44 static func reduce(value: inout CGFloat, nextValue: () -> CGFloat) { value = nextValue() } } struct DividerView: View { @State private var showExtraText = true var body: some View { VStack(spacing: 0) { Text(showExtraText ? "Tap to hide 'More'" : "Tap to show 'More'") .frame(height: 44) if showExtraText { Text("More") .frame(height: 44) } } .frame(maxWidth: .infinity) .background(Color.gray) .onTapGesture { showExtraText.toggle() } } } struct TopView: View { var body: some View { VStack { Spacer() Text("Top") } .padding(0) } } struct BottomView: View { var body: some View { VStack { Text("Bottom") Spacer() } .padding(0) } } #Preview { ContentView() }
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Oct ’24
Is this log noise? "CoreSVG: Error: NULL ref passed to getObjectCoreSVG: Error: NULL ref passed to getObject"
Before I waste time creating an Apple Developer Support ticket, I’m hoping an Apple DTS engineer can confirm if this is just log noise. Here’s the code: import SwiftUI struct ContentView: View { @State private var editMode: EditMode = .inactive @State private var items = ["Item 1", "Item 2", "Item 3"] var body: some View { NavigationStack { List { ForEach(items, id: \.self) { item in Text(item) } .onDelete { indexSet in items.remove(atOffsets: indexSet) } } .environment(\.editMode, $editMode) .toolbar { ToolbarItem(placement: .topBarTrailing) { EditButton() .environment(\.editMode, $editMode) } } } } } #Preview { ContentView() } When you run this code and tap Edit, you’ll initially get: CoreSVG has logged an error. Set environment variabe [sic] "CORESVG_VERBOSE" to learn more. After setting CORESVG_VERBOSE = YES, you’ll see: CoreSVG: Error: NULL ref passed to getObjectCoreSVG: Error: NULL ref passed to getObject This error only appears the first time Edit is tapped after a build and run. It won't happen again, even after force-quitting and reopening the app. The issue also only happens on iOS 18.0 and 18.1—I can’t reproduce it on iOS 17.5. Fortunately, it doesn’t seem to cause any negative side effects. Is this just log noise?
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UIHostingConfiguration + MainActor.assumeIsolated?
I'm trying to use a SwiftUI view as UICalendarView decoration and I get Call to main actor-isolated instance method 'makeContentView()' in a synchronous nonisolated context; this is an error in the Swift 6 language mode in the following code: class Coordinator: NSObject, UICalendarViewDelegate { func calendarView(_ calendarView: UICalendarView, decorationFor dateComponents: DateComponents) -> UICalendarView.Decoration? { .customView { UIHostingConfiguration { ... } .makeContentView() } } } I've fixed using MainActor.assumeIsolated but is this the correct approach or is there a better one? class Coordinator: NSObject, UICalendarViewDelegate { func calendarView(_ calendarView: UICalendarView, decorationFor dateComponents: DateComponents) -> UICalendarView.Decoration? { .customView { MainActor.assumeIsolated { UIHostingConfiguration { ... } .makeContentView() } } } }
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Fatal error: UnsafeRawBufferPointer with negative count
I'm using Xcode 14.1 to start a Core Data project. I created a new Project, checking CoreData. The resulting program works in Preview and in the Simulator. I've changed the data from a Item/timestamp to Locations/title. I plan to add more Attributes but that's for later. I think I've got all the Item instances changed to Locations and timestamp to title. It seems to work OK when in Preview for ContentView.swift but crashes in the Simulator with the error Swift/UnsafeRawBufferPointer.swift:946: Fatal error: UnsafeRawBufferPointer with negative count Any suggestions on what I have done wrong? Thanks. PS, the New Project includes the line Text("Select a location") but Select a location doesn't appear in the Preview.
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Nov ’22