SwiftUI List performance

Description:When an object in a list (created from a fetchrequest) is deleted from a context, and the context is saved, the list does not properly update.Error:Thread 1: Fatal error: Unexpectedly found nil while unwrapping an Optional value (Thrown on line 5 below)struct DetailView: View { @ObservedObject var event: Event var body: some View { Text((event.timestamp!, formatter: dateFormatter)) .navigationBarTitle(Text(Detail)) } }Steps to reproduce:1. Create a new Master Detail App project with SwiftUI and Core Data.2. In the ContentView, set the body to a TabView with the first tab being the prebuilt NavigationView, and add a second arbitrary tab.struct ContentView: View { @Environment(.managedObjectContext) var viewContext var body: some View { TabView { NavigationView { MasterView() .navigationBarTitle(Text(Master)) .navigationBarItems( leading: EditButton(), trailing: Button( action: { withAnimation { Event.create(in: self.viewContext) } } ) { Image(systemName: plus) } ) Text(De

Hi everyone, I want to perform the tutorial from video WWDC19 - 204. Here is an example of building the Rooms application. At 11 minutes, the author of the video, Jacob Xiao, shows how he performs the extract subview operation. But when I try to repeat this operation an error occurs - Cannot find 'room' in scope. My code and code of Jacob Xiao are the same. import SwiftUI struct ContentView: View { var rooms: [Room] = [] var body: some View { NavigationView { List(rooms) { room in ExtractedView() } .navigationBarTitle(Text(Rooms)) } } } struct ContentView_Previews: PreviewProvider { static var previews: some View { ContentView(rooms: testData) } } struct ExtractedView: View { var body: some View { NavigationLink( destination: Text(room.name)) { // Cannot find 'room' in scope Image(room.thumbnailName) .cornerRadius(8) VStack(alignment: .leading) { Text(room.name) Text((room.capacity) people) .font(.subheadline) .foregroundColor(.secondary) } } } } I think the reason is that

I'm replacing Settings screen on my app with SwiftUI. My App's Settings screen have a some fields that have a Toggle Switch, Title, and Subtitle. but It is a hard to correctly reproduces UIListContentConfiguration.subtitleCell() layout in SwiftUI. I'm trying by this code: Toggle(isOn: $someFlag) { VStack(alignment: .leading) { Text(Title) Text(some descriptions about this toggle switch).font(.footnote) } } screenshots: but it has some of issues: wrong font size; subtitle of SwiftUI version is little a bit bigger than UIKit version wrong padding; SwiftUI version has less padding than UIKit version, which makes hard to read (only little a bit, but I want to stick to its small differences) It might be solvable by manually adds padding, specify font sizes etc, but I feel It is wrong way. It should be exists a beautiful way to reproduce it. Is there a correct way to reproduce beautiful UIListContentConfiguration.subtitleCell() layout in SwiftUI? Thanks!

Backstory - I wanted to create a SwiftUI List with a collapsible header. I came up a solution that I will show below in code In short, there's an empty section the size of the header in the List, based on which I get an offset while scrolling and can move the header accordingly And it has been working great, except the only problem so far is that if you have a screen with this component and there's another screen presented modally that causes modifications of the content of the underlying screen with a List, this solution produces a random offset value of 39.5333333333333 The value is exactly the same no matter the size of the header I put in there, and I can't see what is causing it. This ONLY happens when modification happens from a modal screen. The style of the List also doesn't matter, bug happens on all of them So far I found that it happens due to us using UIKit navigation controllers in our app. Shown below are two examples of code, one with UIKit navigatio

Hi all, I am trying to measure the performce of my video game in iOS platform. After launching the debugger and caputre GPU workload (with frame selected as scope), I can not do performance profiling. The error message is: Failed to enable shader profiler. (516). And if I export the GPU trace and reopen it, the Xcode can not find any compatible devices connected. However, the same device used for capturing is connected. Device informations are: Mac device: MacBook Air M2, 2022 Mac OS version: Sonoma 14.4 XCode version: 15.2 (15C500b) mobile device: iPhone 13 Pro Max iOS version: 15.0 GPU performance counter can be performed using the same mobile device in my colleague's Mac. So I think there might be something wrong with my Xcode.

Returning from a sheet nither a click or a tap gesture triggers on a component in a list, until you perform a drag gesture. The best is to see it, so to reproduce the situation I have created a little test. copy and play import SwiftUI enum TriggerType: String, CaseIterable { case button, tapGesture } enum ABC: String, CaseIterable { case A,B,C } struct ContentView: View { @State private var myLetters = [ABC]() @State private var triggerType = TriggerType.button var body: some View { List { // TriggerType Picker(selection: $triggerType, label: Text(no)) { ForEach(TriggerType.allCases, id: .self) { type in Text(type.rawValue) } } .pickerStyle(SegmentedPickerStyle()) // select letter LetterPicker(triggerType: $triggerType ,selected: $myLetters) .disabled(myLetters.count = 3) // view all selected letters ForEach(myLetters, id: .self) { letter in MyButton(triggerType: $triggerType, label: letter.rawValue, symbol: minus.circle.fill, symbolColor: .red) { if let index = myLetters.