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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iPAD custom in app keyboard stopped responding
IOS 12 - 18.1.1 - objective C, Xcode 16.0 App runs on both iPhone and iPad, this issue only occurs happens on iPads. For the iPhones I am able to get a decent numeric only keyboard to display. I pulled down NumericKeypad from GitHub and used that a model on how to implement a custom keypad. In the inputView of the delegate, a new custom text field is create and then assigned a delegate and other properties then it returns the view to the main ViewController. When the ViewControllers and the correct text field is entered my custom keyboard display and the buttons respond but nothing is displayed in the text field. This has worked for years and all of the sudden it stopped. The original project for the example 10 key custom keyboard builds and when loaded that works on the iPad. If I comment out condition to only execute if running on an iPad and test with an iPhone the keyboards works. It is only on a iPad that this happens. This is the cod that creates creates the keyboard from a .xib file. I am using a storyboard for the main app. #import "Numeric10KeyTextField.h" #import "Numeric10KeyViewController.h" @implementation Numeric10KeyTextField (UIView *)inputView { UIView *view = nil; Numeric10KeyViewController *numVC; // Add hook here for iPhone or other devices if needed but now return nil if iPhone so it uses the default // if ([[UIDevice currentDevice] userInterfaceIdiom] == UIUserInterfaceIdiomPad) { numVC = [[Numeric10KeyViewController alloc] initWithNibName:@"Numeric10Key" bundle:nil]; [numVC setActionSubviews:numVC.view]; numVC.delegate = self.numeric10KeyDelegate; numVC.numpadTextField = self; view = numVC.view; // } return view; } @end
Topic: UI Frameworks SubTopic: UIKit Tags:
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459
Feb ’25
Does LazyVStack and LazyVGrid release views from memory inside a ScrollView?
I am using LazyVStack inside a ScrollView. I understand that lazy views are rendered only when they come into view. However, I haven’t heard much about memory deallocation. I observed that in iOS 18 and later, when scrolling up, the bottom-most views are deallocated from memory, whereas in iOS 17, they are not (Example 1). Additionally, I noticed a similar behavior when switching views using a switch. When switching views by pressing a button, the view was intermittently deinitialized. (Example 2). Example 1) struct ContentView: View { var body: some View { ScrollView { LazyVStack { ForEach(0..<40) { index in CellView(index: index) } } } .padding() } } struct CellView: View { let index: Int @StateObject var viewModel = CellViewModel() var body: some View { Rectangle() .fill(Color.accentColor) .frame(width: 300, height: 300) .overlay { Text("\(index)") } .onAppear { viewModel.index = index } } } class CellViewModel: ObservableObject { @Published var index = 0 init() { print("init") } deinit { print("\(index) deinit") } } #Preview { ContentView() } Example 2 struct ContentView: View { @State var index = 0 var body: some View { LazyVStack { Button(action: { if index > 5 { index = 0 } else { index += 1 } }) { Text("plus index") } MidCellView(index: index) } .padding() } } struct MidCellView: View { let index: Int var body: some View { switch index { case 1: CellView(index: 1) case 2: CellView(index: 2) case 3: CellView(index: 3) case 4: CellView(index: 4) default: CellView(index: 0) } } } struct CellView: View { let index: Int @StateObject var viewModel = CellViewModel() var body: some View { Rectangle() .fill(Color.accentColor) .frame(width: 300, height: 300) .overlay { Text("\(index)") } .onAppear { viewModel.index = index } } } class CellViewModel: ObservableObject { @Published var index = 0 init() { print("init") } deinit { print("\(index) deinit") } } -------------------- init init init init init 2 deinit 3 deinit 4 deinit init
Topic: UI Frameworks SubTopic: SwiftUI
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359
Feb ’25
SwiftUI infinite loop issue with @Environment(\.verticalSizeClass)
I see SwiftUI body being repeatedly called in an infinite loop in the presence of Environment variables like horizontalSizeClass or verticalSizeClass. This happens after device is rotated from portrait to landscape and then back to portrait mode. The deinit method of TestPlayerVM is repeatedly called. Minimally reproducible sample code is pasted below. The infinite loop is not seen if I remove size class environment references, OR, if I skip addPlayerObservers call in the TestPlayerVM initialiser. import AVKit import Combine struct InfiniteLoopView: View { @Environment(\.verticalSizeClass) var verticalSizeClass @Environment(\.horizontalSizeClass) var horizontalSizeClass @State private var openPlayer = false @State var playerURL: URL = URL(fileURLWithPath: Bundle.main.path(forResource: "Test_Video", ofType: ".mov")!) var body: some View { PlayerView(playerURL: playerURL) .ignoresSafeArea() } } struct PlayerView: View { @Environment(\.dismiss) var dismiss var playerURL:URL @State var playerVM = TestPlayerVM() var body: some View { VideoPlayer(player: playerVM.player) .ignoresSafeArea() .background { Color.black } .task { let playerItem = AVPlayerItem(url: playerURL) playerVM.playerItem = playerItem } } } @Observable class TestPlayerVM { private(set) public var player: AVPlayer = AVPlayer() var playerItem:AVPlayerItem? { didSet { player.replaceCurrentItem(with: playerItem) } } private var cancellable = Set<AnyCancellable>() init() { addPlayerObservers() } deinit { print("Deinit Video player manager") removeAllObservers() } private func removeAllObservers() { cancellable.removeAll() } private func addPlayerObservers() { player.publisher(for: \.timeControlStatus, options: [.initial, .new]) .receive(on: DispatchQueue.main) .sink { timeControlStatus in print("Player time control status \(timeControlStatus)") } .store(in: &cancellable) } }
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492
Feb ’25
Button taps in scroll views are not cancelled on scroll inside sheets
When you touch down on a button in a scroll view, you can cancel the tap by scrolling. In SwiftUI, this works correctly when the scroll view is not inside a dismissible sheet. However, if the scroll view is inside a sheet that can be dismissed with a drag gesture, scrolling does not cancel the button touch, and after scrolling, the button tap is activated. This happens whether the modal is presented from SwiftUI using the sheet modifier, or wrapped in a UIHostingController and presented from UIKit. This is a huge usability issue for modals with scrollable content that have buttons inside of them. Video of behavior: https://youtube.com/shorts/w6eqsmTrYiU Easily reproducible with this code: import SwiftUI struct ContentView: View { @State private var isPresentingSheet = false var body: some View { ScrollView { LazyVStack { ForEach(0..<100, id: \.self) { index in Button { isPresentingSheet = true } label: { Text("Button \(index)") .padding(.horizontal) .padding(.vertical, 5) .frame(maxWidth: .infinity, alignment: .leading) } } } .padding() } .sheet(isPresented: $isPresentingSheet) { ContentView() } } }
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1.8k
Feb ’25
Lazy cell registration causes crash while dequeue the collectionview cell in collectionview
Cell Registration lazy var headerCell: UICollectionView.SupplementaryRegistration<UICollectionReusableView> = .init(elementKind: UICollectionView.elementKindSectionHeader) { supplementaryView, elementKind, indexPath in } and Cell Dequeue datasource.supplementaryViewProvider = { [weak self] collectionView, kind, indexPath in return collectionView.dequeueConfiguredReusableSupplementary(using: headerCell, for: indexPath) } I am registering a collectionview cell or collwctionview reusable view as lazy variable. It causes a crash like Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'Attempted to dequeue a supplementary view using a registration that was created inside -collectionView:viewForSupplementaryElementOfKind:atIndexPath: or inside a UICollectionViewDiffableDataSource supplementary view provider. Creating a new registration each time a supplementary view is requested will prevent reuse and cause created supplementary views to remain inaccessible in memory for the lifetime of the collection view. Registrations should be created up front and reused. Registration: <UICollectionViewSupplementaryRegistration: 0x600001798a00>
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363
Feb ’25
Multipeer Connectivity with iOS devices
I used the Multipeer Connectivity Framework to allow players of my game app to see the highest score along with their own score as the game progresses. It works fine running in 3 or 4 simulators in Xcode. However, I was just told by two Apple support reps that bluetooth connectivity is not allowed between two Apple devices, other than for watches, AirPods, headphones, etc. My question is: can two iPhones or iPads connect for peer-to-peer play? Can they play offline? If the answer is yes to either or both of those questions, how do I get that to happen since I get an error message when trying to connect two iPhones via bluetooth even though they can see each other in the Other Devices list? If the answer is no, then why does Apple provide a Multipeer Connectivity Framework and simulate that type of device to device connection with the Xcode simulators?
Topic: UI Frameworks SubTopic: SwiftUI
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175
Feb ’25
Are SwiftUI animations in UIKit & AppKit intentionally deprecated?
Is there some reason UIKit's and AppKit's animate(with:changes:completion:) methods are marked deprecated in iOS 18 when they were also first made available in iOS18? If they are indeed already deprecated, is there a replacement method we are supposed to use? This method allows the developer to use SwiftUI animations to animate UIKit and AppKit views.
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372
Feb ’25
Navigation split view selection property is set to nil when selecting list item
I am making a SwiftUI Mac app that uses navigation split view and the Observation framework. The split view has a sidebar list, a detail view, and a selection property to store the selected item in the list. I set the initial selection to the first item in the list using the .onAppear modifier. When I select an item from the list, I get the desired behavior. The detail view shows the contents of the selected item. But the selection property’s value changes to nil. Because selection is nil, I am unable to remove items from the list. Model Code struct Wiki { var pages: [Page] = [] } @Observable class Page: Identifiable, Equatable, Hashable { let id = UUID() var title: String = "Page" var text: String static func == (lhs: Page, rhs: Page) -> Bool { lhs.id == rhs.id } func hash(into hasher: inout Hasher) { hasher.combine(id) hasher.combine(title) hasher.combine(text) } } Split View Code struct ContentView: View { @Binding var wiki: Wiki @State private var selection: Page? = nil var body: some View { NavigationSplitView { PageList(wiki: $wiki, selection: $selection) .navigationSplitViewColumnWidth(ideal: 192) } detail: { if let selection { PageView(page: selection) } else { Text("Select a page to view its contents.") } } .onAppear { selection = wiki.pages.first } } } List Code struct PageList: View { @Binding var wiki: Wiki @Binding var selection: Page? var body: some View { VStack { Text("Pages") .font(.title) List($wiki.pages, selection: $selection) { $page in NavigationLink { PageView(page: page) } label: { TextField("", text: $page.title) } } .padding() } } } Detail View Code struct PageView: View { @Bindable var page: Page var body: some View { TextEditor(text: $page.text) } } I tried changing selection in the list view from @Binding to @Bindable, but I get the following build error: 'init(wrappedValue:)' is unavailable: The wrapped value must be an object that conforms to Observable What fix do I have to make to get the selection property to not be nil when I select an item from the list?
Topic: UI Frameworks SubTopic: SwiftUI
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900
Feb ’25
Swiftui Charts
I have a SwiftUI LineMark chart that inverts the y axis when the data the chart is plotting is all zeros. I'm expecting the y axis 0 to be at the bottom but when the data is all zeros it's at the top. Below is an example demonstrating the problem: import SwiftUI import Charts struct ChartView: View { let data: [Double] = [0,0,0,0,0] var body: some View { Chart { ForEach(data.indices, id: \.self) { index in LineMark( x: .value("Index", index), y: .value("Value", data[index]) ) } } .chartYAxis { AxisMarks(values: [0, 10, 20, 30, 40, 50]) { value in AxisValueLabel() AxisTick() AxisGridLine() } } .padding() } } I can't use .chartYScale(domain: ) because it overrides the chartYAxis where the real code creates custom a leading and trailing y axis. Does anyone have any suggestions how I may fix this?
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554
Feb ’25
fullScreenCover not dismissed if binding changes rapidly.
I'm working on an app targeting iOS 15+ using SwiftUI. The app has several Views that load data from an API in their onAppear() method. While the loading operation is in progress, these views show a loading overlay via .fullScreenCover(). While most of the time this works as expected, I've discovered that if the API operation completes before the overlay's .onAppear() has fired, the overlay gets stuck on screen, i.e. does not dismiss. This bug occurs both in the simulator and on device. This is a simplified version of my implementation: struct MyDataView: View { @EnvironmentObject var store:Store var Content: some View { // ... } @ViewBuilder var body: some View { let showLoadingOverlay = Binding( get: { store.state.loading }, set: { _ in } ) Content .onAppear { store.dispatch(LoadData) } .fullScreenCover(isPresented: showLoadingOverlay) { LoadingOverlay() } } } Log messages tell me that my store is updating correctly, i.e. the booleans all operate as expected. Adding log output to the binding's getter always prints the correct value. Adding a breakpoint to the binding's getter makes the problem disappear. I've found that the chronology of events that lead to this bug is: MyDataView.onAppear() LoadData Binding: true Overlay starts animating in LoadData finishes Binding: false Overlay fires it's onAppear I.e. whenever loading finishes before the fullScreenCover's onAppear is fired, the overlay get's stuck on screen. As long as loading takes at least as long as it takes the overlay to appear, the bug does not occur. It appears to be a race condition between the .fullScreenCover appearing and the binding changing to false. I've found that the bug can be avoided if loading is triggered in the overlay's .onAppear(). However, I would like to avoid this workaround because the overlay is not supposed to carry out data loading tasks.
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1.4k
Feb ’25
Random PDFKit crash on text selection
At this line of code (SketchTextSelectionManager.swift:378), sometimes there will be crashes based on crashlytics reports. In the reports, it seems like this only happens for RTL text range. let selection = pdfPage.selection( from: CGPoint(x: fromStart.x + 1, y: fromStart.y - 1), to: CGPoint(x: toEnd.x - 1, y: toEnd.y + 1) ) This is directly calling into PDFKit's PDFPage#selection method: https://developer.apple.com/documentation/pdfkit/pdfpage/selection(from:to:) Attached the full stacktrace: Crashed: com.apple.root.user-initiated-qos.cooperative 0 CoreGraphics 0x30598c PageLayout::convertRTLTextRangeIndexToStringRangeIndex(long) const + 156 1 CoreGraphics 0x44c3f0 CGPDFSelectionCreateBetweenPointsWithOptions + 224 2 PDFKit 0x91d00 -[PDFPage selectionFromPoint:toPoint:type:] + 168 3 MyApp 0x841044 closure #1 in SketchTextSelectionManager.handleUserTouchMoved(_:) + 378 (SketchTextSelectionManager.swift:378) 4 MyApp 0x840cb0 SketchTextSelectionManager.handleUserTouchMoved(_:) + 205 (CurrentNoteManager.swift:205) 5 libswift_Concurrency.dylib 0x60f5c swift::runJobInEstablishedExecutorContext(swift::Job*) + 252 6 libswift_Concurrency.dylib 0x63a28 (anonymous namespace)::ProcessOutOfLineJob::process(swift::Job*) + 480 7 libswift_Concurrency.dylib 0x6101c swift::runJobInEstablishedExecutorContext(swift::Job*) + 444 8 libswift_Concurrency.dylib 0x62514 swift_job_runImpl(swift::Job*, swift::SerialExecutorRef) + 144 9 libdispatch.dylib 0x15ec0 _dispatch_root_queue_drain + 392 10 libdispatch.dylib 0x166c4 _dispatch_worker_thread2 + 156 11 libsystem_pthread.dylib 0x3644 _pthread_wqthread + 228 12 libsystem_pthread.dylib 0x1474 start_wqthread + 8
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303
Feb ’25
Occasional PDFKit crash at PageLayout::getWordRange(unsigned long, long)
At this line of code (SketchTextSelectionManager.swift:449), sometimes there will be crashes based on crashlytics reports. let selection = pdfPage.selectionForWord(at: location) This is directly calling into PDFKit's PDFPage#selection method: https://developer.apple.com/documentation/pdfkit/pdfpage/selectionforword(at:) Attached the full stacktrace: Crashed: com.apple.root.user-initiated-qos.cooperative 0 CoreGraphics 0x30c968 PageLayout::getWordRange(unsigned long, long) const + 908 1 CoreGraphics 0x30bbc0 PageLayout::getTextRangeIndex(CGPoint, CGPDFSelectionType, SelectionPrecision) const + 2292 2 CoreGraphics 0x44a53c CGPDFSelectionCreateBetweenPointsWithOptions + 384 3 PDFKit 0x8d5f8 -[PDFPage selectionFromPoint:toPoint:type:] + 168 4 PDFKit 0x92040 -[PDFPage _rvItemAtPoint:] + 64 5 PDFKit 0x91f4c -[PDFPage rvItemAtPoint:] + 84 6 PDFKit 0x8caa8 -[PDFPage selectionForWordAtPoint:] + 40 7 MyApp 0x8420e0 closure #1 in SketchTextSelectionManager.startNewTextSelection(pageId:location:) + 449 (SketchTextSelectionManager.swift:449) 8 MyApp 0x841a70 SketchTextSelectionManager.startNewTextSelection(pageId:location:) + 205 (CurrentNoteManager.swift:205) 9 libswift_Concurrency.dylib 0x61104 swift::runJobInEstablishedExecutorContext(swift::Job*) + 252 10 libswift_Concurrency.dylib 0x63a28 (anonymous namespace)::ProcessOutOfLineJob::process(swift::Job*) + 480 11 libswift_Concurrency.dylib 0x611c4 swift::runJobInEstablishedExecutorContext(swift::Job*) + 444 12 libswift_Concurrency.dylib 0x62514 swift_job_runImpl(swift::Job*, swift::SerialExecutorRef) + 144 13 libdispatch.dylib 0x15d8c _dispatch_root_queue_drain + 392 14 libdispatch.dylib 0x16590 _dispatch_worker_thread2 + 156 15 libsystem_pthread.dylib 0x4c40 _pthread_wqthread + 228 16 libsystem_pthread.dylib 0x1488 start_wqthread + 8 ```
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324
Feb ’25
Xcode 16: SwiftUI plain Button & UIImageView not working
It looks like Xcode 16 has changed this behaviour so I'm not sure if this is a bug or not. When a SwiftUI Button wraps a UIImageView and the button style is .plain the button doesn't work without setting isUserInteractionEnabled. struct ContentView: View { var body: some View { Button { print("Hello World!") } label: { UITestImage() } .buttonStyle(.plain) } } struct UITestImage: UIViewRepresentable { func makeUIView(context: Context) -> UIImageView { let view = UIImageView() // view.isUserInteractionEnabled = true // Fix view.image = UIImage(systemName: "plus") view.contentMode = .scaleAspectFit view.setContentCompressionResistancePriority(.defaultLow, for: .horizontal) view.setContentCompressionResistancePriority(.defaultLow, for: .vertical) view.layoutMargins = .zero return view } public func updateUIView(_ uiView: UIImageView, context: Context) {} } This feels unexpected, is this a bug?
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1k
Feb ’25
Foundation (?) mangles diacriticals in Greek Extended (U+1F54)
(NOTE: In sum, this is destructive of user data.) The client is a professor of Classics in constant need of properly-rendered glyphs that represent legitimate code points. As an example, the correct spelling might be: εὔτρητος It is spelled and rendered as intended. A file by this name will be correctly spelled by ls in the Terminal. Note that two diacritics are applied to the second letter, an upsilon (ὔ) However, the Finder displays that file as ἐύτρητος and iterating the string reveals that the accents are improperly distributed over the two. This would never be correct. This handicaps digital-humanities researchers from college to postdoctoral work. A Character by Character iteration demonstrates the mangling.: intended (εὔτρητος) displayed (ἐύτρητος) 3B5 (ε) 1F10 (ἐ) GREEK SMALL LETTER EPSILON, GREEK SMALL LETTER EPSILON WITH PSILI 1F54 (ὔ) 3CD (ύ) GREEK SMALL LETTER UPSILON WITH PSILI AND OXIA GREEK SMALL LETTER UPSILON WITH TONOS 3C4 (τ) 3C4 (τ) (back in sync) 3C1 (ρ) 3C1 (ρ) 3B7 (η) 3B7 (η) 3C4 (τ) 3C4 (τ) 3BF (ο) 3BF (ο) 3C2 (ς) 3C2 (ς) I don't want to muddy the waters by guessing where and how the mistake is made, just see for yourself.
1
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382
Feb ’25
What is a performant way to change view offset as user scrolls?
I added a background view to my SwiftUI List, and would like to move it up as user scrolls (similar to the effect of that of the Health app). I can't add it onto the background of a List row, because List unconditionally clips content to a row, and I would like the view to extend past a insetted row's bounds (scrollClipDisabled does not work on List). So I added the view as the background view of the entire List. Currently, I am achieving this by monitoring contentOffset using the new onScrollGeometryChange(for:of:action:) modifier, updating a state variable that controls the offset of the background view. The code looks something like this: struct ContentView: View { @State private var backgroundOffset: CGFloat = 0 var body: some View { List { ... } .background { backgroundView .offset(y: backgroundOffset) } .onScrollGeometryChange(for: ScrollGeometry.self) { geometry in geometry } action: { oldValue, newValue in let contentOffsetY = newValue.contentOffset.y let contentInsetY = newValue.contentInsets.top if contentOffsetY <= -contentInsetY { backgroundOffset = 0 } else { backgroundOffset = -(contentOffsetY + contentInsetY) } } } } However, this results in bad scrolling performance. I am guessing this is due to backgroundOffset being updated too frequently, and thus refreshing the views too often? If so, what is a more performant approach to achieve the desired effect? Thanks!
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951
Feb ’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?
0
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273
Feb ’25
How can I optimize SwiftUI CPU load on frequent updates
Dear Sirs, I'm writing an audio application that should show up to 128 horizontal peakmeters (width for each is about 150, height is 8) stacked inside a ScrollViewReader. For the actual value of the peakmeter I have a binding to a CGFloat value. The peakmeter works as expected and is refreshing correct. For testing I added a timer to my swift application that is firing every 0.05 secs, meaning I want to show 20 values per second. Inside the timer func I'm just creating random CGFloat values in range of 0...1 for the bound values. The peakmeters refresh and flicker as expected but I can see a CPU load of 40-50% in the activity monitor on my MacBook Air with Apple M2 even when compiled in release mode. I think this is quite high and I'd like to reduce this CPU load. Should this be possible? I.e. I thought about blocking the refresh until I've set all values? How could this be done and would it help? What else could I do? Thanks and best regards, JFreyberger
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1.1k
Feb ’25
A specific image fails to load using UIImageView on iOS 16, but loads normally on systems below iOS 16.
A specific image fails to load properly using UIImageView on iOS 16 and later systems, but loads normally on iOS 15 and earlier versions. Similarly, on Mac computers, this image cannot be opened on MacOS 13 and later, whereas it opens without issue on MacOS 12 and earlier. I am curious about the reasons behind this differing behavior on both iPhone and Mac.
6
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503
Feb ’25
NSTextAttachment lagging in textkit 2
I have an attributedString with 100 NSTextAttachments(contains image of 400kb). When i scroll the textview, it is lagging, When i did the same in textkit 1, it is butter smooth. It can be because of how textkit 1 & 2 layout the elements. let attachment = NSTextAttachment() attachment.image = UIImage(named: "image2") let attachmentString = NSAttributedString(attachment: attachment) let mutableAttributedString = NSMutableAttributedString(attributedString: textView.attributedText) for _ in 0...100 { mutableAttributedString.append(NSAttributedString(string: "\n")) mutableAttributedString.append(attachmentString) } textView.attributedText = mutableAttributedString How to handle images in textkit 2 so that it feels smooth while scrolling textview?
1
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491
Feb ’25