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

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Excessive ressource usage with NavigationLinks in LazyVStack
When a large number of NavigationLinks is within a LazyVStack (or LazyVGrid), ressource usage gets higher (and stays high) the further a user scrolls down. A simple example to reproduce this: NavigationStack { ScrollView { LazyVStack { ForEach(0..<5000) { number in NavigationLink(value: number) { Text("Number \(number)") } } } } .navigationDestination(for: Int.self) { number in Text("Details for number \(number)") } } List does not exhibit this behavior but is not suitable for my use case.
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251
Jan ’25
Implement two lists side by side with SwiftUI on iPad
I'm currently building an App using a TabView as the main navigation method. In my app I would like to build a page similar to the Top Charts in the native App Store App with two lists side by side: So far I came up with this code (simplified demo): import SwiftUI struct Demo: View { var body: some View { TabView { Tab("Main Tab", systemImage: "tray.and.arrow.down.fill") { NavigationStack { HStack { List { Text("Left List") } List { Text("Right List") } } .navigationTitle("Demo") .navigationBarTitleDisplayMode(.inline) } } } } } #Preview { Demo() } However, I’m encountering a couple of issues: • Scrolling to the top of the left list doesn’t trigger the toolbar background effect, and the content overlaps with the tabs in a strange way. Scrolling to the top of the right list works as expected. • The navigation title is always hidden. I haven’t been able to find a solution to these problems. What would be the correct approach? Thank you!
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572
Jan ’25
Production app crashing with PlatformViewHost.updateNestedHosts(_:colorSchemeChanged:)
Hello, my production app is experiencing some crashes according to app store analytics. I cannot seem to reproduce it. According to Xcode Orginzer the app is crashing 10 SwiftUI 0x000000018ec372a0 PlatformViewHost.updateNestedHosts(_:colorSchemeChanged:) + 332 (PlatformViewHost.swift:699) Distributor ID: com.apple.AppStore Hardware Model: iPhone13,4 Version: 2.0.3 (86) AppStoreTools: 15E204 AppVariant: 1:iPhone13,4:16 Code Type: ARM-64 (Native) Role: Foreground Parent Process: launchd [1] OS Version: iPhone OS 17.4.1 (21E236) Exception Type: EXC_CRASH (SIGABRT) Exception Codes: 0x0000000000000000, 0x0000000000000000 Termination Reason: SIGNAL 6 Abort trap: 6 Triggered by Thread: 0 Kernel Triage: VM - (arg = 0x3) mach_vm_allocate_kernel failed within call to vm_map_enter VM - (arg = 0x3) mach_vm_allocate_kernel failed within call to vm_map_enter VM - (arg = 0x3) mach_vm_allocate_kernel failed within call to vm_map_enter VM - (arg = 0x3) mach_vm_allocate_kernel failed within call to vm_map_enter VM - (arg = 0x3) mach_vm_allocate_kernel failed within call to vm_map_enter Thread 0 name: Thread 0 Crashed: 0 libsystem_kernel.dylib 0x00000001d1bd6974 __pthread_kill + 8 (:-1) 1 libsystem_pthread.dylib 0x00000001e56590ec pthread_kill + 268 (pthread.c:1717) 2 libsystem_c.dylib 0x0000000191627c14 __abort + 136 (abort.c:159) 3 libsystem_c.dylib 0x0000000191627b8c abort + 192 (abort.c:126) 4 libswiftCore.dylib 0x000000018832a690 swift::fatalErrorv(unsigned int, char const*, char*) + 136 (Errors.cpp:387) 5 libswiftCore.dylib 0x000000018832a6b0 swift::fatalError(unsigned int, char const*, ...) + 32 (Errors.cpp:395) 6 libswiftCore.dylib 0x0000000188324a08 getNonNullSrcObject(swift::OpaqueValue*, swift::TargetMetadata&lt;swift::InProcess&gt; const*, swift::TargetMetadata&lt;swift::InProcess&gt; const*) + 256 (DynamicCast.cpp:144) 7 libswiftCore.dylib 0x0000000188326510 tryCastToObjectiveCClass(swift::OpaqueValue*, swift::TargetMetadata&lt;swift::InProcess&gt; const*, swift::OpaqueValue*, swift::TargetMetadata&lt;swift::InProcess&gt; const*, swift::TargetMetadata&lt;swift::InPro... + 88 (DynamicCast.cpp:510) 8 libswiftCore.dylib 0x0000000188324068 tryCast(swift::OpaqueValue*, swift::TargetMetadata&lt;swift::InProcess&gt; const*, swift::OpaqueValue*, swift::TargetMetadata&lt;swift::InProcess&gt; const*, swift::TargetMetadata&lt;swift::InProcess&gt; const*&amp;, sw... + 992 (DynamicCast.cpp:2281) 9 libswiftCore.dylib 0x0000000188323b14 swift_dynamicCast + 208 (CompatibilityOverrideRuntime.def:109) 10 SwiftUI 0x000000018ec372a0 PlatformViewHost.updateNestedHosts(_:colorSchemeChanged:) + 332 (PlatformViewHost.swift:699) 11 SwiftUI 0x000000018ec36bf4 PlatformViewHost.updateEnvironment(_:viewPhase:) + 412 (PlatformViewHost.swift:690) 12 SwiftUI 0x000000018ec37bf8 PlatformViewHost.init(_:host:environment:viewPhase:importer:) + 808 (PlatformViewHost.swift:132) 13 SwiftUI 0x000000018ec36cf8 PlatformViewHost.__allocating_init(_:host:environment:viewPhase:importer:) + 92 (PlatformViewHost.swift:0) 14 SwiftUI 0x000000018ec0132c closure #1 in closure #1 in closure #4 in closure #1 in PlatformViewChild.updateValue() + 444 (PlatformViewRepresentable.swift:559) 15 SwiftUI 0x000000018ec06c58 partial apply for closure #1 in closure #1 in closure #4 in closure #1 in PlatformViewChild.updateValue() + 24 (&lt;compiler-generated&gt;:0) 16 SwiftUI 0x000000018ea26910 RepresentableContextValues.asCurrent&lt;A&gt;(do:) + 156 (RepresentableContextValues.swift:43) 17 SwiftUI 0x000000018ec01124 closure #1 in closure #4 in closure #1 in PlatformViewChild.updateValue() + 176 (PlatformViewRepresentable.swift:558) 18 SwiftUI 0x000000018ec0104c closure #4 in closure #1 in PlatformViewChild.updateValue() + 128 (PlatformViewRepresentable.swift:557) 19 SwiftUI 0x000000018ec06b2c partial apply for closure #4 in closure #1 in PlatformViewChild.updateValue() + 24 (&lt;compiler-generated&gt;:0) 20 SwiftUI 0x000000018de7b7d0 closure #1 in _withObservation&lt;A&gt;(do:) + 44 (ObservationUtils.swift:26) 21 SwiftUI 0x000000018ec06b50 partial apply for closure #1 in _withObservation&lt;A&gt;(do:) + 24 (&lt;compiler-generated&gt;:0) 22 libswiftCore.dylib 0x0000000187fd0068 withUnsafeMutablePointer&lt;A, B&gt;(to:_:) + 28 (LifetimeManager.swift:82) 23 SwiftUI 0x000000018ebffbdc closure #1 in PlatformViewChild.updateValue() + 3040 (PlatformViewRepresentable.swift:556) 24 SwiftUI 0x000000018d5ecbf8 partial apply for implicit closure #1 in closure #1 in closure #1 in Attribute.init&lt;A&gt;(_:) + 32 (&lt;compiler-generated&gt;:0) 25 AttributeGraph 0x00000001b2150240 AG::Graph::UpdateStack::update() + 512 (ag-graph-update.cc:578) 26 AttributeGraph 0x00000001b2146f38 AG::Graph::update_attribute(AG::data::ptr&lt;AG::Node&gt;, unsigned int) + 424 (ag-graph-update.cc:719) 27 AttributeGraph 0x00000001b2146810 AG::Graph::input_value_ref_slow(AG::data::ptr&lt;AG::Node&gt;, AG::AttributeID, unsigned int, unsigned int, AGSwiftMetadata const*, unsigned char&amp;, long) + 720 (ag-graph.cc:1429)
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1.2k
Jan ’25
Multi Section Sidebar using List with selections for macOS
I'm trying to implement a 3 column NavigationSplitView in SwiftUI on macOS - very similar to Apple's own NavigationCookbook sample app - with the slight addition of multiple sections in the sidebar similar to how the Apple Music App has multiple sections in the sidebar. Note: This was easily possible using the deprecated NavigationLink(tag, selection, destination) API The most obvious approach is to simply do something like: NavigationSplitView(sidebar: { List { Section("Section1") { List(section1, selection: $selectedItem1) { item in NavigationLink(item.label, value: item) } } Section("Section2") { List(section2, selection: $selectedItem2) { item in NavigationLink(item.label, value: item) } } } }, content: { Text("Content View") }, detail: { Text("Detail View") }) But unfortunately, this doesn't work - it doesn't seem to properly iterate over all of the items in each List(data, selection: $selected) or the view is strangely cropped - it only shows 1 item. However if the 1 item is selected, then the appropriate bindable selection value is updated. See image below: If you instead use ForEach for enumerating the data, that does seem to work, however when you use ForEach, you loose the ability to track the selection offered by the List API, as there is no longer a bindable selection propery in the NavigationLink API. NavigationSplitView(sidebar: { List { Section("Section1") { ForEach(section1) { item in NavigationLink(item.label, value: item) } } Section("Section2") { ForEach(section2) { item in NavigationLink(item.label, value: item) } } } }, content: { Text("Content View") }, detail: { Text("Detail View") }) We no longer know when a sidebar selection has occurred. See image below: Obviously Apple is not going to comment on the expected lifespan of the now deprecated API - but I am having a hard time switching to the new NavigationLink with a broken sidebar implementation.
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582
Jan ’25
Does EV Charging entitlement support CPSearchTemplate?
I am developing a CarPlay app, that has been approved for EV Charging entitlement. Could you please confirm if the given entitlement supports CPSearchTemplate template as there is some confusion here. I tried using the template by referring to the below link, https://developer.apple.com/documentation/carplay/cpsearchtemplate Here is the snippet, class SearchCPView: UIResponder, CPSearchTemplateDelegate { var searchTemplate: CPSearchTemplate = CPSearchTemplate() override init() { super.init() searchTemplate.delegate = self } func getSearchTemplate(interfaceController: CPInterfaceController?) -> CPGridTemplate { let searchGridButton = CPGridButton(titleVariants: [CarplayButtonTitles.search], image: UIImage(named: ImagesConstants.CarPlay.searchGrid) ?? UIImage(), handler: {[self] _ in guard let controller = interfaceController else { return } controller.pushTemplate(self.searchTemplate, animated: true) { status, error in print(status) } }) let gridTemplate = CPGridTemplate(title: "", gridButtons: [searchGridButton]) return gridTemplate } func searchTemplate(_ searchTemplate: CPSearchTemplate, selectedResult item: CPListItem) async { print(item) } func searchTemplate(_ searchTemplate: CPSearchTemplate, updatedSearchText searchText: String) async -> [CPListItem] { print(searchText) return [CPListItem(text: "", detailText: "")] } } On push, I am getting an exception, *** Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'Unsupported object <CPSearchTemplate: 0x30056df00> <identifier: 28, userInfo: (null), tabTitle: (null), tabImage: (null), showsTabBadge: 0> passed to pushTemplate:animated:completion:. Allowed classes: {( CPTabBarTemplate, CPActionSheetTemplate, CPAlertTemplate, CPGridTemplate, CPPointOfInterestTemplate, CPInformationTemplate, CPContactTemplate, CPListTemplate )}'
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345
Jan ’25
How to test iPhone app and CarPlay together?
I have developed a mobile app using SwiftUI. Now I am in the process of building a CarPlay application. I know how to test the CarPlay app using a simulator but here is my confusion, Testing the iPhone app and CarPlay together (few scenarios like user login / logout, location enabled /disabled in the mobile app) Kindly help me validate the above scenarios as I am getting black screen on iPhone whenever the CarPlay is launched. Below is the code snippet, func application(_ application: UIApplication, configurationForConnecting connectingSceneSession: UISceneSession, options: UIScene.ConnectionOptions) -> UISceneConfiguration { if connectingSceneSession.role == .carTemplateApplication { let sceneConfiguration = UISceneConfiguration(name: "CarPlay Scene", sessionRole: connectingSceneSession.role) sceneConfiguration.delegateClass = CarPlaySceneDelegate.self return sceneConfiguration } // Configuration for other types of scenes return UISceneConfiguration(name: "Default Configuration", sessionRole: connectingSceneSession.role) } struct MyApp: App { @UIApplicationDelegateAdaptor(AppDelegate.self) var delegate var body: some Scene { WindowGroup { ContentView() .preferredColorScheme(.light) } } } Info.plist <key>UIApplicationSceneManifest</key> <dict> <key>UIApplicationSupportsMultipleScenes</key> <true/> <key>UISceneConfigurations</key> <dict> <key>CPTemplateApplicationSceneSessionRoleApplication</key> <array> <dict> <key>UISceneConfigurationName</key> <string>CarPlay Scene</string> <key>UISceneDelegateClassName</key> <string>$(PRODUCT_MODULE_NAME).CarPlaySceneDelegate</string> </dict> </array> </dict> </dict>
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433
Jan ’25
Using txt files with searching strings for an iOS app
When dealing with SwiftUI and searchable modifier, I know you can use URL or hard code data to search when building projects in Xcode. I am looking to see if you can use a txt file as a way or storing string data of lists to search from when your device is offline when using the search modifier. Then when connected to internet you can update the search with url connection that then updates the txt file so you can do new searches the next time you are offline again. Is this something that is possible?
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255
Jan ’25
Can't Widgetkit use lottie to implement the isOn state of toggle?
I introduced lottie to toggle in my widget to show a transition animation, but found that the.json file wouldn't load. The loading_hc.json file is validated and exists in the widget target. Ask for help, thank you! struct LottieView: UIViewRepresentable { let animationName: String func makeUIView(context: Context) -> LOTAnimationView { let lotAnimationView = LOTAnimationView(name: animationName, bundle: .main) lotAnimationView.contentMode = .scaleAspectFit lotAnimationView.play() return lotAnimationView } func updateUIView(_ uiView: LOTAnimationView, context: Context) { } func makeCoordinator() -> Coordinator { Coordinator() } } struct ControlToggleDisarmingStyle: ToggleStyle { func makeBody(configuration: Configuration) -> some View { if configuration.isOn { LottieView(animationName: "loading_hc.json").foregroundColor(.clear).frame(width: 24,height: 24) } else { Image("icon_disarm", bundle: Bundle.main).foregroundColor(.clear) } } }
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470
Jan ’25
How to test iPhone app and CarPlay together?
I have developed a mobile app using SwiftUI. Now I am in the process of building a CarPlay application. I know how to test the CarPlay app using a simulator but here is my confusion, How to test the iPhone app and CarPlay together? I want to test few scenarios like, user login / logout from mobile app. Location enabled /disabled in the mobile app. I know that swiftUI handles the scenes by itself. Kindly help me validate the above scenarios as I am getting black screen on iPhone whenever the CarPlay is launched. Below is the code snippet, func application(_ application: UIApplication, configurationForConnecting connectingSceneSession: UISceneSession, options: UIScene.ConnectionOptions) -> UISceneConfiguration { if connectingSceneSession.role == .carTemplateApplication { let sceneConfiguration = UISceneConfiguration(name: "CarPlay Scene", sessionRole: connectingSceneSession.role) sceneConfiguration.delegateClass = CarPlaySceneDelegate.self return sceneConfiguration } // Configuration for other types of scenes return UISceneConfiguration(name: "Default Configuration", sessionRole: connectingSceneSession.role) } struct MyApp: App { @UIApplicationDelegateAdaptor(AppDelegate.self) var delegate var body: some Scene { WindowGroup { ContentView() .preferredColorScheme(.light) } } } Info.plist <key>UIApplicationSceneManifest</key> <dict> <key>UIApplicationSupportsMultipleScenes</key> <true/> <key>UISceneConfigurations</key> <dict> <key>CPTemplateApplicationSceneSessionRoleApplication</key> <array> <dict> <key>UISceneConfigurationName</key> <string>CarPlay Scene</string> <key>UISceneDelegateClassName</key> <string>$(PRODUCT_MODULE_NAME).CarPlaySceneDelegate</string> </dict> </array> </dict> </dict>
2
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624
Jan ’25
iPadOS 18 TabView with Large Navigation Title
I’m following the example code from Apple to implement the new iPadOS 18 TabView() with the new Tab(). While the tabbing itself is working fine, I can’t get it to show up a (large) navigation title in the sidebar (like the Home or Files app). I’ve tried placing .navigationTitle("App Name") at the TabView, but that doesn’t work. Is it possible to do this in any way or is this not recommended to show? TabView { Tab("Overview", systemImage: "film") { Text("Put a OverviewView here") } TabSection("Watch") { Tab("Movies", systemImage: "film") { Text("Put a MoviesView here") } Tab("TV Shows", systemImage: "tv") { Text("Put a TVShowsView here") } } TabSection("Listen") { Tab("Music", systemImage: "music.note.list") { Text("Put a MusicView here") } Tab("Podcasts", systemImage: "mic") { Text("Put a PodcastsView here") } } } .tabViewStyle(.sidebarAdaptable) .navigationTitle("App Name") .navigationBarTitleDisplayMode(.large) I know that there is also the .tabViewSidebarHeader() modifier, but that adds any view above the scroll view content. Neither does that easily allow to make it look like the regular navigation title, nor does it actually display in the navigation bar at the top, when scrolling down.
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1k
Jan ’25
backgroundPreferenceValue does not work after distributed through App Connect
Hi, I'm new to software development and facing a problem that don't know how to solve. I have a piece of code using .backgroundPreferenceValue and .anchorPreference modifiers to monitor a button's position while dragging. It works perfectly on preview, simulator, and my own device if I download it through a cable connected to my computer. However, today I distributed it to TestFlight and found out it broke. I repeated the process serval times but the result is still the same. Has anybody run into the same type of problem before? Desperately need help. Many many thanks!
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392
Jan ’25
SwiftUI - Open a file via a fileURL
I am writing a SwiftUI-based app and have the following requirements: Use a file browser (such as UIDocumentPickerViewController) to find an arbitrary file (not one that the application knows how to open) which is external to the app bundle but local to the device the app is running on - either in local storage or on an iCloud drive. Save this location. At a later time, open this file. The file should open in an app that knows how to open it or in a browser. Do all of the above in a way that works with multiple devices (synced via CloudKit/SwiftData). For example, select a file on my iCloud drive on my Mac, then save it (using CloudKit/SwiftData) and open it on an iPad that has an app that can open it. I am addressing requirement #1 using UIDocumentPickerViewController wrapped with a UIViewControllerRepresentable. It returns a security-scoped URL. (Note: this worries me because of requirement #4). I use the Bookmark API to implement requirement #2. For requirement #3, I load the bookmark data, convert it back to a security-scoped URL and either Link("Open", destination: url) or @Environment(\.openURL) private var openURL if url.startAccessingSecurityScopedResource() { defer { url.stopAccessingSecurityScopedResource() } openURL(url) { accepted in // do something here } } Both of these implementations fail. The Link call responds with "invalid input parameters" (Error Domain=NSOSStatusErrorDomain, Code=-50), the openURL() call just returns false. So, my questions are: Since it appears the Link and openURL work for internet URLs, but not for security-scoped file URLs, how to I cause a document to be opened (using an application which knows how to open it or a browser). Since UIDocumentPickerViewController is returning a security-scoped URL, how can I make this work on a different device than the one on which the user selected the document? (Assuming, of course, that we are talking about a document that is on an iCloud drive that both devices have access to).
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3.6k
Jan ’25
Help Needed: SwiftUI View with Camera Integration and Core ML Object Recognition
Hi everyone, I'm working on a SwiftUI app and need help building a view that integrates the device's camera and uses a pre-trained Core ML model for real-time object recognition. Here's what I want to achieve: Open the device's camera from a SwiftUI view. Capture frames from the camera feed and analyze them using a Create ML-trained Core ML model. If a specific figure/object is recognized, automatically close the camera view and navigate to another screen in my app. I'm looking for guidance on: Setting up live camera capture in SwiftUI. Using Core ML and Vision frameworks for real-time object recognition in this context. Managing navigation between views when the recognition condition is met. Any advice, code snippets, or examples would be greatly appreciated! Thanks in advance!
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734
Jan ’25
Could someone test if Settings in iOS 18.2 are broken ?
Apparently, settings do not show anymore the apps settings in iOS 18.2. I tested on simulators (Xcode 16.2) both on iOS 18.1 and iOS 18.2 and got very different results: In iOS 18.1 simulator, I see the settings of a lot of apps. In iOS 18.2 simulator, not a single app setting. That is a really serious issue in simulator for development (I filed a bug report FB16175635), but would be really critical on device as it would make it impossible to adjust setting of many apps. Unless I missed something (meta setting ?) in iOS 18.2 ? I have not upgraded to 18.2 notably for this reason. So I would appreciate if someone who has upgraded could make the test and report ? select Settings on Home page scroll to Apps category tap here to access the list Does the list show anything ? Thanks for your help.
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1.1k
Jan ’25
Writing to Printer with Core Bluetooth
I have a very cheap Bluetooth-connected printer. And I want to print out a word or two via Core Bluetooth. It's an iOS app with the SwiftUI framework. The following is what I have for an ObservableObject class. import Foundation import CoreBluetooth class BluetoothManager: NSObject, ObservableObject, CBCentralManagerDelegate, CBPeripheralDelegate { @Published var connectedDevices: [CBPeripheral] = [] @Published var powerOn = false @Published var peripheralConnected = false private var centralManager: CBCentralManager! private var peripheralName = "LX-D02" private var connectedPeripheral: CBPeripheral? private var writeCharacteristic: CBCharacteristic? private let serviceUUID = CBUUID(string:"5833FF01-9B8B-5191-6142-22A4536EF123") private let characteristicUUID = CBUUID(string: "FFE1") override init() { super.init() self.centralManager = CBCentralManager(delegate: self, queue: nil) } func startScanning() { if centralManager.state == .poweredOn { centralManager.scanForPeripherals(withServices: nil, options: nil) } } func centralManagerDidUpdateState(_ central: CBCentralManager) { if central.state == .poweredOn { powerOn = true print("Bluetooth is powered on") } else { print("Bluetooth is not available") } } func centralManager(_ central: CBCentralManager, didDiscover peripheral: CBPeripheral, advertisementData: [String : Any], rssi RSSI: NSNumber) { if !connectedDevices.contains(peripheral) { if let localName = advertisementData["kCBAdvDataLocalName"] as? String { if localName == peripheralName { connectedDevices.append(peripheral) centralManager.connect(peripheral, options: nil) centralManager.stopScan() peripheralConnected = true print("Connected: \(peripheral.identifier.uuidString)") } } } } func centralManager(_ central: CBCentralManager, didConnect peripheral: CBPeripheral) { connectedPeripheral = peripheral peripheral.delegate = self let services = [serviceUUID] peripheral.discoverServices(services) //discoverServices(peripheral: peripheral) } func centralManager(_ central: CBCentralManager, didFailToConnect peripheral: CBPeripheral, error: (any Error)?) { guard let error = error else { print("Failed connection unobserved") return } print("Error: \(error.localizedDescription)") } func peripheral(_ peripheral: CBPeripheral, didDiscoverServices error: Error?) { if let error = error { print("Failing to discover servies: \(error.localizedDescription)") return } discoverCharacteristics(peripheral: peripheral) } /* Return all available services */ private func discoverServices(peripheral: CBPeripheral) { peripheral.discoverServices(nil) } private func discoverCharacteristics(peripheral: CBPeripheral) { guard let services = peripheral.services else { return } for service in services { peripheral.discoverCharacteristics(nil, for: service) } } func peripheral(_ peripheral: CBPeripheral, didDiscoverCharacteristicsFor service: CBService, error: Error?) { guard let characteristics = service.characteristics else { return } for characteristic in characteristics { let characteristicUUID = characteristic.uuid print("Discovered characteristic: \(characteristicUUID)") peripheral.setNotifyValue(true, for: characteristic) if characteristic.properties.contains(.writeWithoutResponse) { writeCharacteristic = characteristic print("You can write!!!") // Never read... } if characteristic.properties.contains(.write) { print("You can write?") writeCharacteristic = characteristic // Being read... } } func writeToPrinter() { guard let peripheral = connectedPeripheral else { print("Ughhh...") return } if let characteristic = writeCharacteristic { if let data = "Hello".data(using: .utf8, allowLossyConversion: true) { peripheral.writeValue(data, for: characteristic, type: .withoutResponse) peripheral.writeValue(data, for: characteristic, type: .withResponse) // -> Message sent successfully } } } func peripheral(_ peripheral: CBPeripheral, didWriteValueFor characteristic: CBCharacteristic, error: Error?) { if let error = error { print("Writing error: \(error.localizedDescription)") return } print("Message sent successfully") } } My app has no trouble connecting to the bluetooth-connected printer. Initially, I called discoverServices(peripheral:) to get all services And I get a service identifier (5833FF01-9B8B-5191-6142-22A4536EF123) for my printer. peripheral(_:didDiscoverCharacteristicsFor:error:) doesn't return a thing for .writeWithoutResponse but does return a characteristic for .write. Eventually, if I call writeToPrinter(), peripheral.writeValue(data, for: characteristic, type: .withoutResponse) returns WARNING: Characteristic <CBCharacteristic: 0x3019040c0, UUID = 5833FF02-9B8B-5191-6142-22A4536EF123, properties = 0x8, value = (null), notifying = NO> does not specify the "Write Without Response" property - ignoring response-less write If I call peripheral.writeValue(data, for: characteristic, type: .withResponse) , there is no error. But I get no output from the printer. What am I doing wrong? Thanks.
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482
Jan ’25
I want to know the update principle of the `RealityView`.
Here is the code snippets. struct RealityViewTestView: View { @State private var texts: [String] = [] var body: some View { RealityView { content, attachments in } update: { content, attachments in for text in texts { if let textEntity = attachments.entity(for: text) { textEntity.position.x = Float.random(in: -0.1...0.1) content.add(textEntity) } } } attachments: { ForEach(texts, id: \.self) { text in Attachment(id: text) { Text(text) .padding() .glassBackgroundEffect() } } } .toolbar { ToolbarItem { Button("Add") { texts.append(String(UUID().uuidString.prefix(6))) } } ToolbarItem { Button("Remove") { texts.remove(at: Int.random(in: 0..<texts.count)) } } } } } struct RealityViewTestView: View { @State private var texts: [String] = [] @State private var entities: [Entity] = [] var body: some View { RealityView { content, attachments in } update: { content, attachments in // for text in texts { // if let textEntity = attachments.entity(for: text) { // textEntity.position.x = Float.random(in: -0.1...0.1) // content.add(textEntity) // } // } for entity in entities { content.add(entity) } } attachments: { ForEach(texts, id: \.self) { text in Attachment(id: text) { Text(text) .padding() .glassBackgroundEffect() } } } .toolbar { ToolbarItem { Button("Add") { //texts.append(String(UUID().uuidString.prefix(6))) let m = ModelEntity(mesh: .generateSphere(radius: 0.1), materials: [SimpleMaterial(color: .white, isMetallic: false)]) m.position.x = Float.random(in: -0.2...0.2) entities.append(m) } } ToolbarItem { Button("Remove") { //texts.remove(at: Int.random(in: 0..<texts.count)) entities.removeLast() } } } } } About the first code snippet, when I remove an element from the texts, why content can automatically remove the corresponding entity? And about the second code snippet, content do not automatically remove the corresponding entity. I am very curious.
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437
Jan ’25
searchable issue on iOS 18
Starting with iOS 18, the behavior of searchable and searchSuggestions differs from previous versions. In iOS 17.5, searchSuggestions remained visible even after selecting an item and navigating away. However, in iOS 18, searchSuggestions are dismissed after navigation. Is there a way to keep searchSuggestions visible after navigation, as in iOS 17.5? struct ContentView: View { @State private var query = "" var body: some View { NavigationStack { Color.red .searchable(text: $query) .searchSuggestions { NavigationLink("Element") { Color.blue } } } } } iOS 18.1 iOS 17.5
2
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445
Jan ’25