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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UIDocumentPickerViewController of type pdf cannot pick pdf in simulator
I'm having this problem, with this code: let docPicker = UIDocumentPickerViewController(forOpeningContentTypes: [ .pdf ]) docPicker.delegate = self docPicker.modalPresentationStyle = .currentContext view.window?.rootViewController?.present(docPicker, animated: true, completion: nil) but then when I open the simulator and click the button that calls to the method that has this code... Cannot pick the pdf document. Testing in browserstack with real devices is working, but it's a very slow process, why I cannot use simulators to make work this?
Topic: UI Frameworks SubTopic: UIKit Tags:
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357
Feb ’25
Explanation of DynamicProperty's update func in SwiftUI
Could an Apple employee that works on SwiftUI please explain the update() func in the DynamicProperty protocol? The docs have ambiguous information, e.g. "Updates the underlying value of the stored value." and "SwiftUI calls this function before rendering a view’s body to ensure the view has the most recent value." From: https://developer.apple.com/documentation/swiftui/dynamicproperty/update() How can it both set the underlying value and get the most recent value? What does underlying value mean? What does stored value mean? E.g. Is the code below correct? struct MyProperty: DynamicProperty { var x = 0 mutating func update() { // get x from external storage x = storage.loadX() } } Or should it be: struct MyProperty: DynamicProperty { let x: Int init(x: Int) { self.x = x } func update() { // set x on external storage storage.save(x: x) } } This has always been a mystery to me because of the ambigious docs so thought it was time to post a question.
Topic: UI Frameworks SubTopic: SwiftUI
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220
Jan ’25
Foundation _userInfoForFileAndLine crash
Could anyone give some insights to identify the root cause for this crash? Fatal Exception: NSInternalInconsistencyException Layout requested for visible navigation bar, <UINavigationBar: 0x120e74280; frame = (0 0; 430 56); autoresize = W; tintColor = <UIDynamicProviderColor: 0x300488b20; provider = <__NSMallocBlock__: 0x300a60900>>; layer = <CALayer: 0x3000f0380>> delegate=0x1277a4600 standardAppearance=0x302d5c770 scrollEdgeAppearance=0x302d5d500, when the top item belongs to a different navigation bar. topItem = <UINavigationItem: 0x10a7d8500> title='Transfers' style=navigator leftBarButtonItems=0x300690020 rightBarButtonItems=0x300613ff0, navigation bar = <UINavigationBar: 0x11a8ef200; frame = (0 0; 430 44); opaque = NO; autoresize = W; layer = <CALayer: 0x3002a44c0>> delegate=0x1277a0c00, possibly from a client attempt to nest wrapped navigation controllers. ==== Fatal Exception: NSInternalInconsistencyException 0 CoreFoundation 0x827cc __exceptionPreprocess 1 libobjc.A.dylib 0x172e4 objc_exception_throw 2 Foundation 0x80f8d8 _userInfoForFileAndLine 3 UIKitCore 0x2b63e8 -[UINavigationBar layoutSubviews] 4 UIKitCore 0xd688 -[UIView(CALayerDelegate) layoutSublayersOfLayer:] 5 UIKitCore 0x14dc14 -[UINavigationBar layoutSublayersOfLayer:] 6 QuartzCore 0x78c28 CA::Layer::layout_if_needed(CA::Transaction*) 7 QuartzCore 0x787b4 CA::Layer::layout_and_display_if_needed(CA::Transaction*) 8 QuartzCore 0xcf914 CA::Context::commit_transaction(CA::Transaction*, double, double*) 9 QuartzCore 0x4e7c4 CA::Transaction::commit() 10 QuartzCore 0x91a0c CA::Transaction::flush_as_runloop_observer(bool) 11 UIKitCore 0xa3568 _UIApplicationFlushCATransaction 12 UIKitCore 0xa0b64 __setupUpdateSequence_block_invoke_2 13 UIKitCore 0xa09d8 _UIUpdateSequenceRun 14 UIKitCore 0xa0628 schedulerStepScheduledMainSection 15 UIKitCore 0xa159c runloopSourceCallback 16 CoreFoundation 0x56328 __CFRUNLOOP_IS_CALLING_OUT_TO_A_SOURCE0_PERFORM_FUNCTION__ 17 CoreFoundation 0x562bc __CFRunLoopDoSource0 18 CoreFoundation 0x53dc0 __CFRunLoopDoSources0 19 CoreFoundation 0x52fbc __CFRunLoopRun 20 CoreFoundation 0x52830 CFRunLoopRunSpecific 21 GraphicsServices 0x11c4 GSEventRunModal 22 UIKitCore 0x3d2eb0 -[UIApplication _run] 23 UIKitCore 0x4815b4 UIApplicationMain 24 XX 0xa0f64 main + 7 (main.m:7) 25 ??? 0x1abb6eec8 (Missing)
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1k
Jan ’25
macOS Menu disappears when converting from NSApplicationActivationPolicyAccessory to NSApplicationActivationPolicyRegular if display disconnected and reconnected
I'm not quite sure where the problem is, but I will describe what I am doing to recreate the issue, and am happy to provide whatever information I can to be more useful. I am changing the ActivationPolicy for my app in order to make it unobtrusive when in the background (e.g. hiding it from the dock and using only a menu bar status item). When the user activates the app with a hotkey, it changes from NSApplicationActivationPolicyAccessory back to NSApplicationActivationPolicyRegular. This allows normal usage (dock icon, menu bar, etc.) This works fine, except in a rare situation which I finally just tracked down. If there is a window open in the app and I use the hotkey to convert back to an accessory, and then disconnect and reconnect the display on which the app was previously displayed, when I convert the app back to "regular mode", the menu bar has disappeared (and I am left with an empty space at the top of the screen). I can also trigger this bug by having the display in question briefly mirror the other display (effectively "orphaning" the hidden app), and then restoring the original side-by-side configuration before activating the app again. The app otherwise works, but the menu bar is missing. Switching back and forth with other apps does not fix the problem. Quitting and restarting the app resolves the issue. As does disabling the accessory only mode and forcing the app to always remain in "regular mode" with a dock icon (there is a preference for this in my app). Once fixed, I can then re-enable the "accessory mode" and all is well until the bug is triggered again. The bug would normally occur quite sporadically, presumably requiring a particular combination of changing Spaces or displays, or having the computer go to sleep while this app was in accessory mode. Thus far, the above is the only way I have found that can replicate this issue on demand. If I close all windows before hiding the app, then it works fine when I revert to "regular mode". It only happens if there is a window open at the time. Using applicationDidChangeScreenParameters: on my AppDelegate indicates that there is a change in screen, and logging window.screen.frame for each open window in [NSApp orderedWindows] shows that the size changes from e.g. 1920x1080 to 0x0 and back while the display is disconnected or mirrored. There is also an error in the console in Xcode when this happens -- invalid display identifier <some UUID>. I have tried various options for window collectionBehavior, as well as various settings for Spaces (which I normally use). None of these changes has fixed the behavior thus far. I use [NSApp hide:self]; from my AppDelegate to hide the app, and [[NSRunningApplication currentApplication] activateWithOptions:NSApplicationActivateAllWindows];[NSApp unhide:self]; to bring it back to the front. I welcome any ideas for things to chase down, or requests for more specific information that would be useful. Thank you! Fletcher
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Feb ’25
TextField.preferesDefaultFocus does not work in alerts
Hi, I am having trouble setting default focus on a TextField that is inside of an alert. I expected TextField to receive default focus when alert is presented but result is that TextField does not receive default focus. This is happening on macOS 15.2, Swift (SwiftUI), Xcode 16.2 but hasn't worked on previous versions as well. Example: ContentView().alert("Sample Alert", isPresented: $present) { AlertView() } message: { Text("Sample alert message.") } struct AlertView: View { @Namespace private var namespace @Environment(\.dismiss) private var dismiss @State private var text = "" var body: some View { VStack { TextField(text: $text, prompt: Text("Enter text")) {} .onSubmit { var _ = print(text) dismiss() } .autocorrectionDisabled() .lineLimit(1) .prefersDefaultFocus(in: namespace) Button("OK") { dismiss() } Button("Cancel", role: .cancel) { dismiss() } } .focusScope(namespace) } }
Topic: UI Frameworks SubTopic: SwiftUI
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205
Jan ’25
MacCatalyst Scene Frame needs adjustment
I don't know why, but for my MacCatalyst target, I have to make my view controller Y orgin 36 and the subtract the view height by 36 points, or the view is clipped. The following works in my main UIViewController, but feels super hacky. I'd feel better if I understood the issue and addressed it properly. override func viewWillLayoutSubviews() { super.viewWillLayoutSubviews() #if targetEnvironment(macCatalyst) if view.frame.origin.y < 1 { let f = UIApplication.shared.sceneBounds let newFrame = CGRect(x: 0.0, y: 36, width: f.size.width, height: f.size.height - 36) self.view.frame = newFrame } #endif } My guess is it starts the view under the title bar, but I have these set in the view controller: self.extendedLayoutIncludesOpaqueBars = false self.edgesForExtendedLayout = []
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Jan ’25
SwiftData integration for coexistence with CoreData Error: Persistent truncated
When integrating SwiftData for an already existing app that uses CoreData as data management, I encounter errors. When building the ModelContainer for the first time, the following error appears: Error: Persistent History (184) has to be truncated due to the following entities being removed (all Entities except for the 2 where I defined a SwiftData Model) class SwiftDataManager: ObservableObject { static let shared = SwiftDataManager() private let persistenceManager = PersistenceManager.shared private init(){} lazy var modelContainer: ModelContainer = { do { let storeUrl = persistenceManager.storeURL() let schema = Schema([ HistoryIncident.self, HistoryEvent.self ]) let modelConfig = ModelConfiguration(url: storeUrl) return try ModelContainer(for: schema, configurations: [modelConfig]) } catch { fatalError("Could not create ModelContainer: \(error)") } }() } @Model public class HistoryIncident { var missionNr: String? @Relationship(deleteRule: .cascade) var events: [HistoryEvent]? public init(){} } @Model class HistoryEvent { var decs: String? var timestamp: Date? init(){} } As soon as I call the following function. func addMockEventsToCurrentHistorie() { var descriptor = FetchDescriptor<HistoryIncident>() let key = self.hKey ?? "" descriptor.predicate = #Predicate { mE in key == mE.key } let historyIncident = try? SwiftDataManager.shared.modelContext.fetch(descriptor).first guard var events = historyIncident?.events else {return} events.append(contentsOf: createEvents()) } I get the error: CoreData: error: (1) I/O error for database at /var/mobile/Containers/Data/Application/55E9D59D-48C4-4D86-8D9F-8F9CA019042D/Library/ Private Documents/appDatabase.sqlite. SQLite error code:1, 'no such column: t0.Z1EVENTS' /var/mobile/Containers/Data/Application/55E9D59D-48C4-4D86-8D9F-8F9CA019042D/Library/ Private Documents/appDatabase.sqlite. SQLite error code:1, 'no such column: t0.Z1EVENTS' with userInfo of { NSFilePath = "/var/mobile/Containers/Data/Application/55E9D59D-48C4-4D86-8D9F-8F9CA019042D/Library/ Private Documents/appDatabase.sqlite"; NSSQLiteErrorDomain = 1; }
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645
Feb ’25
SwiftUI Transformable: support drag to Finder on macOS
I am trying to support dragging out a 'file' object from my app into Finder, on macOS. I have my object conform to Transferable and the files are saved on disk locally, so I just want to pass it the URL. This works fine when dragging out to other apps, like Notes or Mail, but not in Finder. I setup a ProxyRepresentation as well, as suggested by another thread, but it doesn't seem to help. Is there any other setup I need to do in the Xcode project file for it to work, or is there something else that I'm missing? @available(iOSApplicationExtension 17.0, macOSApplicationExtension 14.0, *) extension FileAttachments: Transferable { public static var transferRepresentation: some TransferRepresentation { FileRepresentation(exportedContentType: UTType.content) { content in SentTransferredFile(content.fullFileURL(), allowAccessingOriginalFile: false) } .exportingCondition { file in if let fileUTI = UTType(filenameExtension: file.fullFileURL().pathExtension), let fileURL = file.fullFileURL() { print("FileAttachments: FileRepresentation exportingCondition fileUTI: \(fileUTI) for file: \(fileURL)") return fileUTI.conforms(to: UTType.content) } return false } .suggestedFileName{$0.fileRenamedName} ProxyRepresentation { file in if let fileURL = file.fullFileURL() { print("FileAttachments: ProxyRepresentation returning file") return fileURL } return file.fullFileURL()! } } }
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376
Feb ’25
Unrealistically high snowfall amounts being reported by WeatherKit
I filed FB16332997 about the VERY high snowfall estimates I'm seeing in WeatherKit and iOS Weather. I initially thought something was wrong with my weather app but I verified the numbers with the iOS Weather app and another third party weather app. For Atlanta last week it was saying 7.5" when it ended up being 2" (which I can live with). Two days ago it reported there could be 16" of snow in northern Florida. That's impossible! This morning it was reporting that Niceville could have 6-7" of snow, which would be significantly more than highest amount in recorded history for Florida (where snow is extremely rare). It almost makes me wonder if the liquid precipitation value is actually the snowfall amount in reality. And then that is incorrectly being converted to the snowfall amount.
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469
Jan ’25
Setting rounded corners via CAShapeLayer.path looks problematic
class ViewController: UIViewController { override func viewDidLoad() { super.viewDidLoad() view.backgroundColor = .white do { let shapeLayer = CAShapeLayer() shapeLayer.frame = CGRect(x: 50, y: 100, width: 200, height: 108) let path = UIBezierPath(roundedRect: shapeLayer.bounds, cornerRadius: 36) shapeLayer.path = path.cgPath shapeLayer.fillColor = UIColor.orange.cgColor view.layer.addSublayer(shapeLayer) } do { let layer = CALayer() layer.backgroundColor = UIColor.blue.cgColor layer.cornerRadius = 36 layer.frame = CGRect(x: 50, y: 300, width: 200, height: 108) view.layer.addSublayer(layer) } } } The corner radius is set to 36 through CAShapeLayer, but the actual effect is larger than 36, close to half of the height. Setting it through CALayer is fine Can anyone explain it to me? Thank you
Topic: UI Frameworks SubTopic: UIKit Tags:
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306
Feb ’25
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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226
Jan ’25
iOS 18 Button with accented image is broken(cannot tap) in desktop widget.
In iOS 18 widget, button is broken when it's has an accented desaturated image as content, the button's AppIntent will not trigger perform function. checkout the code below: ` struct WidgetExtEntryView : View { var entry: Provider.Entry var body: some View { VStack { Text("count:") Text("\(WidgetExtAppIntent.count)") HStack { // button can not be tapped Button(intent: WidgetExtAppIntent(action: "+1")) { VStack { Image(systemName: "plus.square.fill").resizable() .widgetAccentedRenderingMode(.accentedDesaturated) // <-- here .frame(width: 50, height: 50) Text("Broken") } }.tint(.red) // button can be tapped Button(intent: WidgetExtAppIntent(action: "+1")) { VStack { Image(systemName: "plus.square.fill").resizable() .widgetAccentedRenderingMode(.fullColor) // <-- here .frame(width: 50, height: 50) Text("OK").frame(width: 50, alignment: .center) } }.tint(.green) } .minimumScaleFactor(0.5) } } } ` check out the full demo project: ButtonInWidgetBrokenIOS18
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346
Jan ’25
MVVM design and data dependency
According to the MVVM design pattern, one of my views depends on many properties in my model. Can I use logic like @published var model = MyModel()? Will there be a large performance loss? Will the UI be refreshed when other unrelated properties in the model are modified? What is the best practice in this case?
Topic: UI Frameworks SubTopic: General
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248
Jan ’25
XCode breakpoint possible for "Publishing changes from within view updates is not allowed, this will cause undefined behavior."?
Dear Sirs, I'm searching for the most straightforward way to identify the root of a "Publishing changes from within view updates is not allowed, this will cause undefined behavior." warning. It is a complex SwiftUI project and I think there should be a better way than just try and error with disabling/removing and enabling/adding different screen elements to check if the warning still is shown. I tried to set a symbolic breakpoint for "os_log" in my XCode project and indeed this is triggered right before the warning appears but the callstack doesn't give me a direct hint to the part of my code which causes this warning. What would be the most direct way and is there something like an exception handler in such cases? Thanks and best regards, Johannes
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475
Jan ’25
Dynamically Update Complex UI Views in SwiftUI
I am working on a SwiftUI project where I need to dynamically update the UI by adding or removing components based on some event. The challenge is handling complex UI structures efficiently while ensuring smooth animations and state management. Example Scenario: I have a screen displaying a list of items. When a user taps an item, additional details (like a subview or expanded section) should appear dynamically. If the user taps again, the additional content should disappear. The UI should animate these changes smoothly without causing unnecessary re-renders. My Current Approach: I have tried using @State and if conditions to toggle views, like this: struct ContentView: View { @State private var showDetails = false var body: some View { VStack { Button("Toggle Details") { showDetails.toggle() } if showDetails { Text("Additional Information") .transition(.slide) // Using animation } } .animation(.easeInOut, value: showDetails) } } However, in complex UI scenarios where multiple components need to be shown/hidden dynamically, this approach is not maintainable and could cause performance issues. I need help with the below questions. Questions: State Management: Should I use @State, @Binding, or @ObservedObject for handling dynamic UI updates efficiently? Best Practices: What are the best practices for structuring SwiftUI views to handle dynamic updates without excessive re-renders? Performance Optimization: How can I prevent unnecessary recomputations when updating only specific UI sections? Animations & Transitions: What is the best way to apply animations smoothly while toggling visibility of multiple components? Advanced Approaches: Are there better techniques using @EnvironmentObject, ViewBuilder, or even GeometryReader for dynamically adjusting UI layouts? Any insights, code examples, or resources would be greatly appreciated.
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348
Jan ’25
Unexpected Insertion of U+2004 (Space) When Using UITextView with Pinyin Input on iOS 18
I encountered an issue with UITextView on iOS 18 where, when typing Pinyin, extra Unicode characters such as U+2004 are inserted unexpectedly. This occurs when using a Chinese input method. Steps to Reproduce: 1. Set up a UITextView with a standard delegate implementation. 2. Use a Pinyin input method to type the character “ㄨ”. 3. Observe that after the character “ㄨ” is typed, extra spaces (U+2004) are inserted automatically between the characters. Code Example: class ViewController: UIViewController { @IBOutlet weak var textView: UITextView! override func viewDidLoad() { super.viewDidLoad() // Do any additional setup after loading the view. } } extension ViewController: UITextViewDelegate { func textView(_ textView: UITextView, shouldChangeTextIn range: NSRange, replacementText text: String) -> Bool { print("shouldChangeTextIn: range \(range)") print("shouldChangeTextIn: replacementText \(text)") return true } func textViewDidChange(_ textView: UITextView) { let currentText = textView.text ?? "" let unicodeValues = currentText.unicodeScalars.map { String(format: "U+%04X", $0.value) }.joined(separator: " ") print("textViewDidChange: textView.text: \(currentText)") print("textViewDidChange: Unicode Scalars: \(unicodeValues)") } } Output: shouldChangeTextIn: range {0, 0} shouldChangeTextIn: replacementText ㄨ textViewDidChange: textView.text: ㄨ textViewDidChange: Unicode Scalars: U+3128 ------------------------ shouldChangeTextIn: range {1, 0} shouldChangeTextIn: replacementText ㄨ textViewDidChange: textView.text: ㄨ ㄨ textViewDidChange: Unicode Scalars: U+3128 U+2004 U+3128 ------------------------ shouldChangeTextIn: range {3, 0} shouldChangeTextIn: replacementText ㄨ textViewDidChange: textView.text: ㄨ ㄨ ㄨ textViewDidChange: Unicode Scalars: U+3128 U+2004 U+3128 U+2004 U+3128 This issue may affect text processing, especially in cases where precise text manipulation is required, such as calculating ranges in shouldChangeTextIn.
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1.1k
Jan ’25