I’m experiencing significant performance and memory management issues in my SwiftUI application when displaying a large number of images using LazyVStack within a ScrollView. The application uses Swift Data to manage and display images.
Here’s the model I’m working with:
@Model
final class Item {
var id: UUID = UUID()
var timestamp: Date = Date.now
var photo: Data = Data()
init(photo: Data = Data(), timestamp: Date = Date.now) {
self.photo = photo
self.timestamp = timestamp
}
}
extension Item: Identifiable {}
The photo property is used to store images. However, when querying Item objects using Swift Data in a SwiftUI ScrollView, the app crashes if there are more than 100 images in the database.
Scrolling down through the LazyVStack loads all images into memory leading to the app crashing when memory usage exceeds the device’s limits.
Here’s my view: A LazyVStack inside a ScrollView displays the images.
struct LazyScrollView: View {
@Environment(\.modelContext) private var modelContext
@State private var isShowingPhotosPicker: Bool = false
@State private var selectedItems: [PhotosPickerItem] = []
@Query private var items: [Item]
var body: some View {
NavigationStack {
ScrollView {
LazyVStack {
ForEach(items) { item in
NavigationLink {
Image(uiImage: UIImage(data: item.photo)!)
.resizable()
.scaledToFit()
} label: {
Image(uiImage: UIImage(data: item.photo)!)
.resizable()
.scaledToFit()
}
}
}
}
.navigationTitle("LazyScrollView")
.photosPicker(isPresented: $isShowingPhotosPicker, selection: $selectedItems, maxSelectionCount: 100, matching: .images)
.onChange(of: selectedItems) {
Task {
for item in selectedItems {
if let data = try await item.loadTransferable(type: Data.self) {
let newItem = Item(photo: data)
modelContext.insert(newItem)
}
}
try? modelContext.save()
selectedItems = []
}
}
}
}
}
Based on this:
How can I prevent SwiftUI from loading all the binary data (photo) into memory when the whole view is scrolled until the last item?
Why does SwiftUI not free memory from the images that are not being displayed?
Any insights or suggestions would be greatly appreciated. Thank you!
I will put the full view code in the comments so anyone can test if needed.
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If you add the .scaleEffect() modifier to a parent view inside of which there are children with contextMenu()-s, the context menu preview unfortunately keeps the original, unscaled size of the child view. This results in a very weird, glitchy user experience.
Unfortunately, providing a custom preview that is scaled up also does not help, since even though it is the right size, it gets cropped to the unscaled size of the child view.
Adding scaleEffect() to each child element individually (BEFORE the contextMenu() modifier!) does make the problem disappear. However, I would like to avoid this, since my use case is zooming into a complex graph with context menus on its nodes, and having to recalculate the position of each node manually seems to perform much worse than delegating that work to scaleEffect().
Tested on iOS 18.2 (device + emulator)
Is there a workaround?
Here is a minimal working example that demonstrates the problem:
struct ContentView: View {
var body: some View {
VStack(spacing: 20) {
Rectangle()
.frame(width: 100, height: 100)
.contextMenu {
Button("Test") {}
Button("Test") {}
}
Rectangle()
.frame(width: 100, height: 100)
.contextMenu {
Button("Test") {}
Button("Test") {}
}
}
.scaleEffect(1.5)
}
}
Screenshot (problem: The two squares are the same size. However, the long-tapped upper square got shrunk down before the context menu got displayed.)
Topic:
UI Frameworks
SubTopic:
SwiftUI
I want to have my own background and foreground colors for some views and I am having a bit of trouble. I cannot figure out how to remove the margins around some built-in views. One example is below. The ScrollView portion is always black or white, depending on whether I am I dark mode or not. I've added various colors and borders to see what is going on below. I've also tried adding the modifiers to the Scroll View rather than the TextEditor and it doesn't work at all. If I don't have the .frame modifier on the ScrollView, the TextEditor moves to the top of its frame for some reason. I've played with .contentMargins, .edgeInsets, etc. with no luck
How do I get the TextEditor to fill the entire ScrollView without the margin? Thanks!
import SwiftUI
struct TextEditorView: View
{ @Binding var editString: String
var numberOfLines: Int
var lineHeight: CGFloat
{ UIFont.preferredFont(forTextStyle: .body).lineHeight
}
var viewHeight: CGFloat
{ lineHeight * CGFloat(numberOfLines) + 8
}
var body: some View
{ ScrollView([.vertical], showsIndicators: true)
{ TextEditor(text: $editString)
.border(Color.red, width: 5)
.foregroundStyle(.yellow)
.background(.blue)
.frame(minHeight:viewHeight, maxHeight: viewHeight)
.scrollContentBackground(.hidden)
}
.frame(minHeight:viewHeight, maxHeight: viewHeight)
}
}
I tried to create a Text View using attributedString. I want to set the line height using paragraphStyle and return the Text, but paragraphStyle is not being applied. Why is that?
extension Text {
init?(_ content: String, font: StyleType, color: Color = .ppBlack) {
var attributedString = AttributedString(content)
attributedString.font = Font.custom(font.fontWeight, fixedSize: font.fontSize)
attributedString.foregroundColor = color
let paragraphStyle = NSMutableParagraphStyle()
paragraphStyle.minimumLineHeight = 16
paragraphStyle.maximumLineHeight = 16
paragraphStyle.lineSpacing = 0
attributedString.mergeAttributes(.init([.paragraphStyle: paragraphStyle]))
self = Text(attributedString)
}
}
Hi! I'm trying to do a forEach loop on an array of objects. Here's my code :
ForEach($individus) { $individu in
if individu.reussite == true {
individu.score -= 10
} else {
individu.score = (individu.levees * 10) + 20 + individu.score
}
}
I have an error on the code in the 'if' saying that "Type '()' cannot conform to 'View'", but I have no idea on how solving this problem.
Topic:
UI Frameworks
SubTopic:
SwiftUI
Its important to note that this same app did not have this issue in iOS 17.
Ever since iOS 18 I have noticed that when application written in SwiftUI uses Label with the default color (which auto changes between light and dark appearance), from time to time when resuming an application that has been in the background, the color of those labels (only the Label elements) switches from the opposite to the correct one. Here is an example:
Steps to reproduce
Phone is in dark appearance
Open app
Labels text color is white and labels background is black
Go to home so that app is on background
Wait random time (does not happen all the time), some times 1 min some times 10
Reopen the application.
During the opening transition the Label text color was changed while the app was in suspended mode to the light appearance variant (black)
Once the app opening transition finishes the Label text color switches back to the correct color for dark appearance (white)
Same issue happens if you start from light appearance. I cannot reproduce this on Xcode simulators, I have tried to force memory warning to check if that has anything to do with it but that also does not cause the issue to appear on simulators. For now I can only reproduce this on real device.
Screenshots
Here is screenshots of the above example:
During transition
After transition
Topic:
UI Frameworks
SubTopic:
SwiftUI
More specifically, if I have 2 pinned tabs that are displayed in different order for compact and regular and switch between compact and regular, when it gets to regular mode, the images for both tabs will not be rendered. The tabs can still be pressed, just the icon is missing.
Is there any way to change the height of the "day" cells in the UICalendarView? The view is very tall on the screen and I'd like to shorten it so I can put more content below it without using a scroll view.
I'm using SwiftUI with a UICalendarView with UIViewRepresentable. The calendar will have default decorations to indicate a date with events.
Topic:
UI Frameworks
SubTopic:
SwiftUI
Hi,,
How can I make a rectangle become taller as I swipe down on my trackpad?"
struct BlueRectangleView: View {
var body: some View {
VStack {
Rectangle()
.fill(Color.blue)
.frame(width: 200, height: 100)
.cornerRadius(10)
.shadow(radius: 5)
.padding()
}
.frame(maxWidth: .infinity, maxHeight: .infinity)
.background(Color.white)
}
}
struct BlueRectangleView_Previews: PreviewProvider {
static var previews: some View {
BlueRectangleView()
}
}
When I switched to observable, I noticed a strange behavior of the ViewModel. The ViewModel is created 3x times. And my question is:
How to properly initialize the ViewModel via state?
Below is a minimal example with log output:
ViewModel INIT : EBBB2C41
ViewModel INIT : D8E490DA
ViewModel INIT : 54407300
ViewModel DEINIT: D8E490DA
@Observable
final class ViewModel {
@ObservationIgnored let idd: UUID
init() {
idd = UUID()
print("ViewModel INIT : \(idd.uuidString.prefix(8))")
}
deinit {
print("ViewModel DEINIT: \(idd.uuidString.prefix(8))")
}
}
struct SimpleView: View {
@Environment(ViewModel.self) private var viewModel
var body: some View {
@Bindable var viewModel = viewModel
Text("SimpleView: \(viewModel.idd.uuidString.prefix(8))")
}
}
struct ContentView: View {
@State private var viewModel = ViewModel()
var body: some View {
SimpleView()
.environment(mainViewModel)
}
}
I'm pretty new to Swift and SwiftUI. I'm making my first app for sorting a gallery with some extra features.
I was using my own iPhone for testing and just started testing my app on other Apple products.
Everything works fine on iPad Air M1, iPhone 15 Pro, iPhone 15 Pro Max, iPhone 13, iPhone XS (Simulator), and iPhone 11 Pro (Simulator). However, when I tried to show my app to a family member with an iPhone 11, I came across an issue.
Issue Description:
My app takes all photos from iPhone's native gallery, then you can sort it by some spesific filters and delete pictures. It just looks like the native gallery. (I can add photos later if needed) You can just scroll the gallery by swiping up and down. You can press the select button and start selecting pictures to delete.
I recently added a drag-to-select-multiple-pictures feature. This makes it feel more like the native iOS experience, eliminating the need to tap each picture individually.
However, on the iPhone 11, the moment you open the app, you can't scroll. Scrolling is completely locked. You can still select pictures by tapping or dragging, so it's not a touch area issue. The same issue persists on the iPhone 11 simulator.
And I think I found the problematic part in my (sadly messy) ContentView.swift file;
ScrollView {
RefreshControl(coordinateSpace: .named("refresh")) {
await viewModel.refreshMediaItems()
}
LazyVGrid(columns: gridColumns, spacing: UIDevice.current.userInterfaceIdiom == .pad ? 12 : 4) {
let items = viewModel.filteredItems(typeFilter: mediaTypeFilter, specialFilter: specialFilter)
ForEach(Array(zip(items.indices, items)), id: \.1.id) { index, item in
MediaThumbnailView(
item: item,
isSelected: selectedItems.contains(item.id),
viewModel: viewModel,
onLongPress: {
if !isSelectionMode {
toggleSelectionMode()
selectedItems.insert(item.id)
}
},
onTap: {
if isSelectionMode {
toggleSelection(item: item)
} else {
viewModel.selectItem(item)
}
}
)
.aspectRatio(1, contentMode: .fit)
.background(
GeometryReader { geometry in
let frame = geometry.frame(in: .named("grid"))
Color.clear.preference(
key: ItemBoundsPreferenceKey.self,
value: [ItemBounds(id: item.id, bounds: frame, index: index)]
)
}
)
}
}
.padding(.horizontal, 2)
.coordinateSpace(name: "grid")
.onPreferenceChange(ItemBoundsPreferenceKey.self) { bounds in
itemBounds = Dictionary(uniqueKeysWithValues: bounds.map { ($0.id, $0) })
itemIndices = Dictionary(uniqueKeysWithValues: bounds.map { ($0.id, $0.index) })
}
.gesture(
DragGesture(minimumDistance: 0)
.onChanged { gesture in
if isSelectionMode {
let location = gesture.location
if !isDragging {
startDragging(at: location, in: itemBounds)
}
updateSelection(at: location, in: itemBounds)
}
}
.onEnded { _ in
endDragging()
}
)
}
.coordinateSpace(name: "refresh")
}
you can see the .gesture(.... part. I realised that this DragGesture and ScrollView blocks each other (somehow only on iPhone 11)
highPriorityGesture also won't work.
When I change it with simultaneousGesture, scroll starts to work again.
BUT - since it's simultaneous, when multiple selection mode is activated, when I'm dragging my finger gallery also starts to scroll and it becomes a very unpleasant experience. After this issue I realised on native gallery iOS locks scroll when you are dragging for multiple selection and just when you release your finger you can scroll again even if the multiple selection mode is active.
I tried a million things, asked claude, chatgpt etc. etc.
Found some similar issues on stackoverflow but they were all related to iOS 18, not spesific to an iPhone. My app works fine on iOS 18 (15 Pro Max)
iOS 18 drag gesture blocks scrollview
Here are the some of the things I've tried: using highPriorityGesture and simultenousgesture together, tried to lock the scroll briefly while dragging, implement much complicated versions of these things with the help of claude, try to check if isSelectionMode is true or not
All of them broke other things/won't work.
Probably there's something pretty simple that I'm just missing; but iPhone 11 being the single problematic device confuses me. I don't want to mess too much with my already fragile logic.
I have a UITextView being added at runtime to a UIImageView as the result of doing text recognition. It's set to be editable = NO and selectable = YES. When I set the text and select it, it asks the delegate for the menu to display via:
textView:editMenuForTextInRange:suggestedActions:
The suggested items contains many UIAction and UICommand objects that have private methods or do not have the destructive attribute set, yet they are destructive. Some of these are:
promptForReplace:
transliterateChinese:
_insertDrawing:
_showTextFormattingOptions:
I need to return a menu that has only non-destructive commands in it.
First, why isn't UITextView sending only non-destructive suggested commands when its editable is NO?
Second, how can I filter the array of suggested commands when it's impossible to know if they're destructive (as some are missing that attribute)?
In addition to that, even non-destructive commands are causing an unrecognized selector exception, such as the Speak command, which it is sending to my view controller instead of to the UITextView, which is the only thing that knows what the text is that it should speak.
Topic:
UI Frameworks
SubTopic:
UIKit
I am developing a custom Picture in Picture (PiP) app that plays videos.
The video continues to play even when the app goes to the background, but I would like to be able to get the bool value when the PiP is hidden on the edge, as shown in the attached image.
The reason why we need this is because we don't want the user to consume extra network bandwidth, so we want to pause the video when the PiP is hidden on the edge of the screen.
Please let me know if this is possible.
This can be done in the foreground or in the background.
I've been trying to add a header to the tabSection of the tabview in tvos 18+ .
init(
@TabContentBuilder<SelectionValue> content: () -> Content,
@ViewBuilder header: () -> Header
) where Header : View, Footer == EmptyView
Here the ehader clearly conforms to View but i cant quite fit the label with uiimage as the icon into this. This Label when i add it to any other view, the image is in the specified 50 x 50 size but inside header it functions weirdly to be of a huge size. but also to note, if i simply hav an icon here, it is correct. So what is the problem here.. can someone help me? im supposed to add the user profile and name in the header. I dont think there's any other way
I tried to use AppIntentConfiguration in iOS17 to fail to achieve such a dynamic configuration.
code:
struct ConfigurationAppIntent: WidgetConfigurationIntent {
static var title: LocalizedStringResource { "位置" }
static var description: IntentDescription { "选择位置以展示城市天气" }
@Parameter(title: "Select City", optionsProvider: CityOptionsProvider())
var selectedCity: String?
}
Topic:
UI Frameworks
SubTopic:
SwiftUI
can't see what the problem is .. Im getting the error:
Type '()' cannot conform to 'View'
struct CalendarView: View {
@StateObject private var viewModel = CalendarViewModel()
@State private var selectedDate: CalendarDate?
@State private var showModal = false
var body: some View {
VStack {
Text("Calendar App")
.font(.largeTitle)
.padding()
GridStack(rows: 5, columns: 7) { row, col in
let index = row * 7 + col
if index < viewModel.calendarDates.count {
let calendarDate = viewModel.calendarDates[index]
Text("\(Calendar.current.component(.day, from: calendarDate.date))")
.frame(width: 40, height: 40)
.background(calendarDate.isSelected ? Color.blue : Color.clear)
.cornerRadius(10)
.foregroundColor(calendarDate.isSelected ? Color.white : Color.black)
.onLongPressGesture {
selectedDate = calendarDate
showModal = true
}
}
}
}
.background(Color.gray)
.sheet(isPresented: $showModal) {
if let date = selectedDate {
DateSelectionModal(selectedDate: date)
}
}
}
}
struct GridStack<Content: View>: View {
let rows: Int
let columns: Int
let content: (Int, Int) -> Content
var body: some View {
VStack {
ForEach(0..<rows) { row in
HStack {
ForEach(0..<columns) { column in
content(row, column)
}
}
}
}
}
}
#Preview {
CalendarView()
}
Topic:
UI Frameworks
SubTopic:
SwiftUI
I am really confused by some of the new data returned in WeatherKit for iOS 18.
The visibility (of an object) was already being returned in HourWeather as a Measurement.
iOS 18 added max/min visibility (of terrain) in DayWeather. BUT instead of a Measurement it's just a Double.
HourWeather:
/// The distance at which an object can be clearly seen.
///
/// The amount of light and weather conditions like fog, mist, and smog affect visibility.
public var visibility: Measurement<UnitLength>
DayWeather's comment:
/// The maximum distance at which terrain is visible for the day.
///
/// The amount of light, and weather conditions like fog, mist, and smog affect visibility.
@available(iOS 18.0, macOS 15.0, tvOS 18.0, watchOS 11.0, visionOS 2.0, *)
public var maximumVisibility: Double
This makes it sound like the new items are also a distance and not a percentage.
Why wasn't Measurement used so the unit would be clear? Documentation doesn't explain this either. I'm hoping that this isn't being returned in the unit used by the current locale because my app lets you specify what unit to use for temperature, length, etc regardless of locale. Since all the temperature, length, etc data returned had used Measurement that was possible.
The iOS weather app refers to the lowest/highest visibility in my preferred unit, which is miles.
Hi everyone! I'm thrilled to share that I'm conducting a field research as part of my final university project, focused on iOS architecture.
The goal is to dive deeper into the best practices, challenges, and trends in the iOS development world. To make this research truly impactful, I need your help!
If you're an iOS developer, I’d love it if you could take a few minutes to answer a short survey. Your insights and experiences will be invaluable for my research, and I greatly appreciate your
support!
Here is the link:
https://docs.google.com/forms/d/e/1FAIpQLSdf9cacfA7my1hnlazyl7uJraa2oTsQ7dJBWvFtZ_4vbYenRA/viewform?usp=send_form
Thank you so much in advance for helping me out—feel free to share this post with others who might also be interested. Let’s build something amazing together! 💡✨
One of my clients is interested in developing a system similar to BrowserStack for internal team usage. Could you please guide me on how to approach the development of this system?
Specifically, the project requires:
Full iPhone screen recording.
Capturing and executing click events on the iPhone.
Do I need to obtain permission from Apple for these functionalities?
Create an Empty visionOS App like this.
starts in windowed mode, when I enter immersive mode and then exit back to windowed mode, I notice that the window appears dimmer. I start a simple project with settings as image shown below, and took screenShots of my window before and after entering immersive space then quit, compare them, the color value did become dimmer. The issue is reliably repeatable in a given room. If this issue is experienced, adjusting the display brightness to the maximum value and then back to the initial setting will restore the colors to the correct state. Force to exit the app then reopen it can do the same restoration.https://drive.google.com/file/d/1m-a4ghNlSkHhAQuvOCF_IAfcdYeJA14j/view?usp=sharing