Hi, I'm working on visionOS and find I can't get onDisappear event just on the first window after app launch. It comes like that:
WindowGroup(id:"WindowA"){
MyView()
.onDisappear(){
print("WindowA disappear")
}
}
WindowGroup(id:"WindowB"){
MyView()
.onDisappear(){
print("WindowB disappear")
}
}
WindowGroup(id:"WindowC"){
MyView()
.onDisappear(){
print("WindowC disappear")
}
}
When the app first launch, it will open WindowA automatically
And then I open WindowB and WindowC programatically.
Then I tap the close button on window bar below window.
If I close WindowB/WindowC, I can receive onDisappear event
If I close WindowA, I can't receive onDisappear event
If I reopen WindowA after it is closed and then close it again by tap the close button below window, I can receive onDisappear event
Is there any logic difference for the first window on app launch? How can I get onDisappear Event for it.
I'm using Xcode 16 beta 2
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Hi folks,
I've used a NavigationSplitView within one of the tabs of my app since iOS 16, but with the new styling in iOS 18 the toolbar region looks odd. In other tabs using e.g. simple stacks, the toolbar buttons are horizontally in line with the new tab picker, but with NavigationSplitView, the toolbar leaves a lot of empty space at the top (see below). Is there anything I can do to adjust this, or alternatively, continue to use the old style?
Thanks!
Hello, community and Apple engineers. I need your help.
Our app has the following issue: NavigationStack pushes a view twice if the NavigationStack is inside TabView and NavigationStack uses a navigation path of custom Hashable elements.
Our app works with issues in Xcode 18 Beta 13 + iOS 18.0. The same issue happened on previous beta versions of Xcode 18.
The issue isn’t represented in iOS 17.x and everything worked well before iOS 18.0 beta releases.
I was able to represent the same issue in a clear project with two simple views. I will paste the code below.
Several notes:
We use a centralised routing system in our app where all possible routes for navigation path are implemented in a View extension called withAppRouter().
We have a enum RouterDestination that contains all possible routes and is resolved in withAppRouter() extension.
We use Router class that contains @Published var path: [RouterDestination] = [] and this @Published property is bound to NavigationStack. In the real app, we need to have an access to this path property for programmatic navigation purposes.
Our app uses @ObservableObject / @StateObject approach.
import SwiftUI
struct ContentView: View {
@StateObject private var router = Router()
var body: some View {
TabView {
NavigationStack(path: $router.path) {
NavigationLink(value: RouterDestination.next, label: {
Label("Next", systemImage: "plus.circle.fill")
})
.withAppRouter()
}
}
}
}
enum RouterDestination: Hashable {
case next
}
struct SecondView: View {
var body: some View {
Text("Screen 2")
}
}
class Router: ObservableObject {
@Published var path: [RouterDestination] = []
}
extension View {
func withAppRouter() -> some View {
navigationDestination(for: RouterDestination.self) { destination in
switch destination {
case .next:
return SecondView()
}
}
}
}
Below you can see the GIF with the issue:
What I tried to do:
Use iOS 17+ @Observable approach. It didn’t help.
Using @State var path: [RouterDestination] = [] directly inside View seems to help. But it is not what we want as we need this property to be @Published and located inside Router class where we can get an access to it, and use for programmatic navigation if needed.
I ask Apple engineers to help with that, please, and if it is a bug of iOS 18 beta, then please fix it in the next versions of iOS 18.0
I added gesture support to my app that supports iOS 16 and 17 and have never had issues with it.
However, when I compiled my app with Xcode 16 I immediately noticed a problem with the app when I ran it in the simulator. I couldn't scroll up or down. I figured out it’s because of my gesture support.
My gesture support is pretty simple.
let myDragGesture = DragGesture()
.onChanged { gesture in
self.offset = gesture.translation
}
.onEnded { _ in
if self.offset.width > threshold {
...some logic
} else if self.offset.width < -threshold {
...some other logic
}
logitUI.debug("drag gesture width was \(self.offset.width)")
self.offset = .zero
}
If I pass nil to .gesture instead of myDragGesture then scrolling starts working again.
Here’s some example output when I’m trying to scroll down. These messages do NOT appear when I run my app on an iOS 16/17 simulator with Xcode 15.
drag gesture width was 5.333328
drag gesture width was -15.333344
drag gesture width was -3.000000
drag gesture width was -24.333328
drag gesture width was -30.666656
I opened FB14205678 about this.
demo code :
- (void)drawRect:(CGRect)rect {
CGContextRef context = UIGraphicsGetCurrentContext();
// Flip the coordinate system
CGContextSetTextMatrix(context, CGAffineTransformIdentity);
CGContextTranslateCTM(context, 0, self.bounds.size.height);
CGContextScaleCTM(context, 1.0, -1.0);
NSDictionary *attrs = @{NSFontAttributeName: [UIFont systemFontOfSize:20],
NSForegroundColorAttributeName: [UIColor blueColor],
NSUnderlineStyleAttributeName: @(NSUnderlineStyleThick),
};
// Make an attributed string
NSAttributedString *attributedString = [[NSAttributedString alloc] initWithString:@"Hello CoreText!" attributes:attrs];
CFAttributedStringRef attributedStringRef = (__bridge CFAttributedStringRef)attributedString;
// Simple CoreText with CTFrameDraw
CTFramesetterRef framesetter = CTFramesetterCreateWithAttributedString(attributedStringRef);
CGPathRef path = CGPathCreateWithRect(self.bounds,NULL);
CTFrameRef frame = CTFramesetterCreateFrame(framesetter,CFRangeMake(0, 0),path,NULL);
//CTFrameDraw(frame, context);
// You can comment the line 'CTFrameDraw' and use the following lines
// draw with CTLineDraw
CFArrayRef lines = CTFrameGetLines(frame);
CGPoint lineOrigins[CFArrayGetCount(lines)];
CTFrameGetLineOrigins(frame, CFRangeMake(0, 0), lineOrigins);
for (int i = 0; i < CFArrayGetCount(lines); i++) {
CTLineRef line = CFArrayGetValueAtIndex(lines, i);
CGContextSetTextPosition(context, lineOrigins[i].x, lineOrigins[i].y);
// CTLineDraw(line, context);
// You can comment the line 'CTLineDraw' and use the following lines
// draw with CTRunDraw
// use CTRunDraw will lost some attributes like NSUnderlineStyleAttributeName,
// so you need draw it by yourself
CFArrayRef runs = CTLineGetGlyphRuns(line);
for (int j = 0; j < CFArrayGetCount(runs); j++) {
CTRunRef run = CFArrayGetValueAtIndex(runs, j);
CTRunDraw(run, context, CFRangeMake(0, 0));
}
}
}
this code will use CTRunDraw to draw the content , and the underline will draw and show normally in iOS17 & Xcode 15 , But when you build it with XCode16 & iOS18 beta . the underline will be missing .
The SF Symbols app 6.0 (99) does not export the ‘Can Rotate’ property of layers when exporting a symbol via File > Export Symbol.
Without this, all the new fantastic edit functions in the app related to rotating in SF Symbols is completely useless.
This issue with the SF Symbols 6 app can be reproduced by exporting a rotatable symbol like fan.desk, and then by importing the result as custom symbol. When inspecting ‘Group 1’ of the imported symbol, it is no longer marked as rotatable.
SF Symbols app 6.0 is still in beta, but hasn't been updated since 10 June. Hopefully this bug will be solved in the release version, or earlier.
Does anyone know how to manually add the missing rotation info to the exported SVG file?
In case an Apple engineer reads this: FB13916635
onContinueUserActivity(CSSearchableItemActionType, perform) works as expected on iOS when we search and select an item from Spotlight, but nothing happens when we do the same on a SwiftUI macOS app.
var body: some Scene {
WindowGroup {
MyView()
.onContinueUserActivity(CSSearchableItemActionType, perform: handleSpotlight)
}
}
func handleSpotlight(_ userActivity: NSUserActivity) {
// Is not called...
}
How can we respond to a user clicking a Spotlight result from our apps on macOS?
With the new @Observable macro, it looks like every time the struct of a view is reinitialized, any observable class marked as @State in the struct also gets reinitialized. Moreover, the result of the reinitialization immediately gets discarded.
This is in contrast to @StateObject and ObservableObject, where the class would only be initialized at the first creation of the view. The initialization method of the class would never be called again between view updates.
Is this a bug or an expected behavior? This redundant reinitialization causes performance issues when the init method of the observable class does anything slightly heavyweight.
Feedback ID: FB13697724
Has anyone been able to create a Control Center widget that opens a snippet view? There are stock Control Center widgets that do this, but I haven't been able to get it to work.
Here's what I tried:
struct SnippetButton: ControlWidget {
var body: some ControlWidgetConfiguration {
StaticControlConfiguration(
kind: "xxx.xxx.snippetWidget"
) {
ControlWidgetButton(action: SnippetIntent()) {
Label("Show Snippet", systemImage: "map.fill")
}
}
.displayName(LocalizedStringResource("Show Snippet"))
.description("Show a snippet.")
}
}
struct SnippetIntent: ControlConfigurationIntent {
static var title: LocalizedStringResource = "Show a snippet"
static var description = IntentDescription("Show a snippet with some text.")
@MainActor
func perform() async throws -> some IntentResult & ProvidesDialog & ShowsSnippetView {
return .result(dialog: IntentDialog("Hello!"), view: SnippetView())
}
}
struct SnippetView: View {
var body: some View {
Text("Hello!")
}
}
How can we performantly scroll to a target location using TextKit 2?
Hi everyone,
I'm building a custom text editor using TextKit 2 and would like to scroll to a target location efficiently. For instance, I would like to move to the end of a document seamlessly, similar to how users can do in standard text editors by using CMD + Down.
Background:
NSTextView and TextEdit on macOS can navigate to the end of large documents in milliseconds. However, after reading the documentation and experimenting with various ideas using TextKit 2's APIs, it's not clear how third-party developers are supposed to achieve this.
My Code:
Here's the code I use to move the selection to the end of the document and scroll the viewport to reveal the selection.
override func moveToEndOfDocument(_ sender: Any?) {
textLayoutManager.ensureLayout(for: textLayoutManager.documentRange)
let targetLocation = textLayoutManager.documentRange.endLocation
let beforeTargetLocation = textLayoutManager.location(targetLocation, offsetBy: -1)!
textLayoutManager.textViewportLayoutController.layoutViewport()
guard let textLayoutFragment = textLayoutManager.textLayoutFragment(for: beforeTargetLocation) else {
return
}
guard let textLineFragment = textLayoutFragment.textLineFragment(for: targetLocation, isUpstreamAffinity: true) else {
return
}
let lineFrame = textLayoutFragment.layoutFragmentFrame
let lineFragmentFrame = textLineFragment.typographicBounds.offsetBy(dx: 0, dy: lineFrame.minY)
scrollToVisible(lineFragmentFrame)
}
While this code works as intended, it is very inefficient because ensureLayout(_:) is incredibly expensive and can take seconds for large documents.
Issues Encountered:
In my attempts, I have come across the following two issues.
Estimated Frames: The frames of NSTextLayoutFragment and NSTextLineFragment are approximate and not precise enough for scrolling unless the text layout fragment has been fully laid out.
Laying out all text is expensive: The frames become accurate once NSTextLayoutManager's ensureLayout(for:) method has been called with a range covering the entire document. However, ensureLayout(for:) is resource-intensive and can take seconds for large documents. NSTextView, on the other hand, accomplishes the same scrolling to the end of a document in milliseconds.
I've tried using NSTextViewportLayoutController's relocateViewport(to:) without success. It's unclear to me whether this function is intended for a use case like mine. If it is, I would appreciate some guidance on its proper usage.
Configuration:
I'm testing on macOS Sonoma 14.5 (23F79), Swift (AppKit), Xcode 15.4 (15F31d).
I'm working on a multi-platform project written in AppKit and UIKit, so I'm looking for either a single solution that works in both AppKit and UIKit or two solutions, one for each UI framework.
Question:
How can third-party developers scroll to a target location, specifically the end of a document, performantly using TextKit 2?
Steps to Reproduce:
The issue can be reproduced using the example project (download from link below) by following these steps:
Open the example project.
Run the example app on a Mac. The example app shows an uneditable text view in a scroll view. The text view displays a long text.
Press the "Move to End of Document" toolbar item.
Notice that the text view has scrolled to the bottom, but this took several seconds (~3 seconds on my MacBook Pro 16-inch, 2021). The duration will be shown in Xcode's log.
You can open the ExampleTextView.swift file and find the implementation of moveToEndOfDocument(_:). Comment out line 84 where the ensureLayout(_:) is called, rerun the app, and then select "Move to End of Document" again. This time, you will notice that the text view moves fast but does not end up at the bottom of the document.
You may also open the large-file.json in the project, the same file that the example app displays, in TextEdit, and press CMD+Down to move to the end of the document. Notice that TextEdit does this in mere milliseconds.
Example Project:
The example project is located on GitHub:
https://github.com/simonbs/apple-developer-forums/tree/main/how-can-we-performantly-scroll-to-a-target-location-using-textkit-2
Any advice or guidance on how to achieve this with TextKit 2 would be greatly appreciated.
Thanks in advance!
Best regards,
Simon
I'm building a SwiftUI app with a UITextView subclass, and it seems that the software keyboard doesn't trigger the pressesBegan or pressesEnded functions of UITextView. With a hardware keyboard, pressesBegan works as expected, allowing us to intercept key presses in our subclass.
I can't find any documentation about this, or any other forum posts (here or on Stack Overflow) that talk about a discrepancy between software and hardware keyboard behaviors, and I can't believe this is an intended behavior. Our app is a SwiftUI app, in case that's relevant.
Does anyone have any guidance? Is this a bug or am I not understanding this API? Any information or work arounds would be greatly appreciated.
I've made a sample project that demonstrates this issue, which you can grab from GitHub at https://github.com/nyousefi/KeyPressSample. To see this in action, run the sample project and start pressing keys. The hardware keyboard will print the key press at the top of the screen (above the text view), while the software keyboard won't.
i export apple SF as custom sf for test.
code is simple:
var body: some ControlWidgetConfiguration {
StaticControlConfiguration(
kind:"ControlWidgetConfiguration"
) {
ControlWidgetButton(action: DynamicWidgetIntent()) {
Text("test")
Image("custom_like")
}
}.displayName("test")
}
as we can see, it can't show image in the preview. but it can show image in the Control widget center.
am i do some thing wrong?
On testing my app with tvOS 18, I have noticed the Siri Remote back button no longer provides system-provided behavior when interacting with tab bar controller pages. Instead of moving focus back to the tab bar when pressed, the back button will close the app, as if the Home button was pressed. This occurs both on device and in the Simulator.
Create tvOS project with a tab bar controller.
Create pages/tabs which contain focusable items (ie. buttons)
Scroll down to any focusable item (ie. a button or UICollectionView cell)
Hit the Siri Remote back button. See expect behavior below:
Expected behavior: System-provided behavior should move focus back to the tab bar at the top of the screen.
Actual results: App is closed and user is taken back to the Home Screen.
Has anyone else noticed this behavior?
I created a Radar for this FB14766095, but thought I would add it here for extra visibility, or if anyone else had any thoughts on the issue.
Basic Information
Please provide a descriptive title for your feedback:
iOS 18 hit testing functionality differs from iOS 17
What type of feedback are you reporting?
Incorrect/Unexpected Behavior
Description:
Please describe the issue and what steps we can take to reproduce it:
We have an issue in iOS 18 Beta 6 where hit testing functionality differs from the expected functionality in iOS 17.5.1 and previous versions of iOS.
iOS 17: When a sheet is presented, the hit-testing logic considers subviews of the root view, meaning the rootView itself is rarely the hit view.
iOS 18: When a sheet is presented, the hit-testing logic changes, sometimes considering the rootView itself as the hit view.
Code:
import SwiftUI
struct ContentView: View {
@State var isPresentingView: Bool = false
var body: some View {
VStack {
Text("View One")
Button {
isPresentingView.toggle()
} label: {
Text("Present View Two")
}
}
.padding()
.sheet(isPresented: $isPresentingView) {
ContentViewTwo()
}
}
}
#Preview {
ContentView()
}
struct ContentViewTwo: View {
@State var isPresentingView: Bool = false
var body: some View {
VStack {
Text("View Two")
}
.padding()
}
}
extension UIWindow {
public override func hitTest(_ point: CGPoint, with event: UIEvent?) -> UIView? {
/// Get view from superclass.
guard let hitView = super.hitTest(point, with: event) else { return nil }
print("RPTEST rootViewController = ", rootViewController.hashValue)
print("RPTEST rootViewController?.view = ", rootViewController?.view.hashValue)
print("RPTEST hitView = ", hitView.hashValue)
if let rootView = rootViewController?.view {
print("RPTEST rootViewController's view memory address: \(Unmanaged.passUnretained(rootView).toOpaque())")
print("RPTEST hitView memory address: \(Unmanaged.passUnretained(hitView).toOpaque())")
print("RPTEST Are they equal? \(rootView == hitView)")
}
/// If the returned view is the `UIHostingController`'s view, ignore.
print("MTEST: hitTest rootViewController?.view == hitView", rootViewController?.view == hitView)
print("MTEST: -")
return hitView
}
}
Looking at the print statements from the provided sample project:
iOS 17 presenting a sheet from a button tap on the ContentView():
RPTEST rootViewController's view memory address: 0x0000000120009200
RPTEST hitView memory address: 0x000000011fd25000
RPTEST Are they equal? false
MTEST: hitTest rootViewController?.view == hitView false
RPTEST rootViewController's view memory address: 0x0000000120009200
RPTEST hitView memory address: 0x000000011fd25000
RPTEST Are they equal? false
MTEST: hitTest rootViewController?.view == hitView false
iOS 17 dismiss from presented view:
RPTEST rootViewController's view memory address: 0x0000000120009200
RPTEST hitView memory address: 0x000000011fe04080
RPTEST Are they equal? false
MTEST: hitTest rootViewController?.view == hitView false
RPTEST rootViewController's view memory address: 0x0000000120009200
RPTEST hitView memory address: 0x000000011fe04080
RPTEST Are they equal? false
MTEST: hitTest rootViewController?.view == hitView false
iOS 18 presenting a sheet from a button tap on the ContentView():
RPTEST rootViewController's view memory address: 0x000000010333e3c0
RPTEST hitView memory address: 0x0000000103342080
RPTEST Are they equal? false
MTEST: hitTest rootViewController?.view == hitView false
RPTEST rootViewController's view memory address: 0x000000010333e3c0
RPTEST hitView memory address: 0x000000010333e3c0
RPTEST Are they equal? true
MTEST: hitTest rootViewController?.view == hitView true
You can see here ☝️ that in iOS 18 the views have the same memory address on the second call and are evaluated to be the same. This differs from iOS 17.
iOS 18 dismiss
RPTEST rootViewController's view memory address: 0x000000010333e3c0
RPTEST hitView memory address: 0x0000000103e80000
RPTEST Are they equal? false
MTEST: hitTest rootViewController?.view == hitView false
RPTEST rootViewController's view memory address: 0x000000010333e3c0
RPTEST hitView memory address: 0x0000000103e80000
RPTEST Are they equal? false
MTEST: hitTest rootViewController?.view == hitView false
The question I want to ask:
Is this an intended change, meaning the current functionality in iOS 18 is expected?
Or is this a bug and it's something that needs to be fixed?
As a user, I would expect that the hit testing functionality would remain the same from iOS 17 to iOS 18.
Thank you for your time.
I have an NSStatusBar application. This is my first in SwiftUI. And I need to know when the window is closed so that I can disable some of menu commands. I can use NSWindowDelegate with AppDelegate as follows.
import SwiftUI
@main
struct SomeApp: App {
@NSApplicationDelegateAdaptor(AppDelegate.self) var appDelegate
@StateObject private var menuViewModel = MenuViewModel()
var body: some Scene {
WindowGroup {
ContentView()
.environmentObject(menuViewModel)
}
}
}
class AppDelegate: NSObject, NSApplicationDelegate, NSWindowDelegate {
private var menuViewModel = MenuViewModel()
func applicationDidFinishLaunching(_ notification: Notification) {
if let window = NSApplication.shared.windows.first {
window.setIsVisible(false)
window.delegate = self
}
}
func windowWillClose(_ notification: Notification) {
menuViewModel.windowClosed = true
}
}
When the window will close, MenuViewModel (ObservableObject) will receive a call, which I want my ContentView to receive. But, so far, it won't.
import SwiftUI
struct ContentView: View {
var body: some View {
ZStack {
...
...
}
.onReceive(statusBarViewModel.$windowClosed) { result in
// never called...
}
}
}
Can a SwiftUI View receive a call somehow when its window closes? Muchos thankos.
Hi, everyone
I have an app already in production that uses SwiftUI's lifecycle (paired with an AppDelegate). Due to some specific behaviour of the app, we decided to migrate the app to use UIKit's lifecycle, adding the corresponding SceneDelegate to the app, as well as modifying the Info.plist file accordingly to accommodate to these new changes.
Although everything seems to work when installing the app from zero, when installing it on top of another version, the screen goes black and the user cannot interact with the app at all unless they reinstall it completely. As I've read online, iOS is reusing the window configuration from the previous execution of the app. I know this because the AppDelegate's application(application:connectingSceneSession:options) is not being called when coming from a previous version of the app.
I would love to know what can I do to make this work because, as you may understand, we cannot ask our user base to reinstall the application.
Thank you very much.
When displaying a view with a Button inside a ScrollView using the sheet modifier, if you try to close the sheet by swiping and your finger is touching the Button, the touch is not canceled.
This issue occurs when building with Xcode 16 but does not occur when building with Xcode 15.
Here is screen cast.
https://drive.google.com/file/d/1GaOjggWxvjDY38My4JEl-URyik928iBT/view?usp=sharing
Code
struct ContentView: View {
@State var isModalPresented: Bool = false
var body: some View {
ScrollView {
Button {
debugPrint("Hello")
isModalPresented.toggle()
} label: {
Text("Hello")
.frame(height: 44)
}
Button {
debugPrint("World")
} label: {
Text("World")
.frame(height: 44)
}
Text("Hoge")
.frame(height: 44)
.contentShape(Rectangle())
.onTapGesture {
debugPrint("Hoge")
}
}
.sheet(isPresented: $isModalPresented) {
ContentView()
}
}
}
I'm using NSTextTable to format panels of stand-out text within body text. Paragraphs within the panel are handled as individual NSTextTableBlocks within the table. Each block is added to the NSMutableParagraphStyle that is part of the attributed string within the block's attributes. That's all fine and it works.
But...
Occasionally I see undrawn lines within the panel. These disappear (or sometimes appear) when the parent window (and thus the NSTextView holding the rendered attributed string) is resized. Lines do not always appear, and when they do they are not always in the same place. The height of the gap varies.
I see this behaviour with these panels and with tables. What's common to both cases is not only the use of NSTextTable and NSTextTableBlock etc., but crucially (I think) the use of block margins. If I disable margins (which looks OK for the panels, but isn't right for tables), the problem disappears.
So, a bug or (more likely) I'm missing a key part of view rendering or margin set up. But what? Code here: https://github.com/smittytone/PreviewMarkdown/blob/930f5f32aa0b3b77ec3f4f53436a79e10bb26f18/Markdown%20Previewer/Styler.swift#L882
Running 14.6.1 on an M3. I'm using TextKit 1 because I'm using an NSLayoutManager subclass to override certain text underlines (not used in panels as outlined above, or tables).
Topic:
UI Frameworks
SubTopic:
AppKit
Based on this TextKit 2 demo project I thought that I could implement syntax highlighting by parsing syntax block tokens (e.g. comments like <!-- --> or /* */) in processEditing and storing their locations, and then actually applying the rendering with NSTextContentStorageDelegate in textContentStorage(_:textParagraphWith:) by checking the location of each paragraph against the store of syntax tokens.
This sort of works except that the rendering is only updated for paragraphs which are changed.
Is there a way to trigger NSTextContentStorage to re-fetch paragraphs in a given range? Or is this a totally misguided approach to the problem?
Hello there!
I wanted to give a native scrolling mechanism for the Swift Charts Graph a try and experiment a bit if the scenario that we try to achieve might be possible, but it seems that the Swift Charts scrolling performance is very poor.
The graph was created as follows:
X-axis is created based on a date range,
Y-axis is created based on an integer values between moreless 0-320 value.
the graph is scrollable horizontally only (x-axis),
The time range (x-axis) for the scrolling content was set to one year from now date (so the user can scroll one year into the past as a minimum visible date (.chartXScale).
The X-axis shows 3 hours of data per screen width (.chartXVisibleDomain).
The data points for the graph are generated once when screen is about to appear so that the Charts engine can use it (no lazy loading implemented yet).
The line data points (LineMark views) consist of 2880 data points distributed every 5 minutes which simulates - two days of continuous data stream that we want to present. The rest of the graph displays no data at all.
The performance result:
The graph on the initial loading phase is frozen for about 10-15 seconds until the data appears on the graph.
Scrolling is very laggy - the CPU usage is 100% and is unacceptable for the end users.
If we show no data at all on the graph (so no LineMark views are created at all) - the result is similar - the empty graph scrolling is also very laggy.
Below I am sharing a test code:
@main
struct ChartsTestApp: App {
var body: some Scene {
WindowGroup {
ContentView()
Spacer()
}
}
}
struct LineDataPoint: Identifiable, Equatable {
var id: Int
let date: Date
let value: Int
}
actor TestData {
func generate(startDate: Date) async -> [LineDataPoint] {
var values: [LineDataPoint] = []
for i in 0..<(1440 * 2) {
values.append(
LineDataPoint(
id: i,
date: startDate.addingTimeInterval(
TimeInterval(60 * 5 * i) // Every 5 minutes
),
value: Int.random(in: 1...100)
)
)
}
return values
}
}
struct ContentView: View {
var startDate: Date {
return endDate.addingTimeInterval(-3600*24*30*12) // one year into the past from now
}
let endDate = Date()
@State var dataPoints: [LineDataPoint] = []
var body: some View {
Chart {
ForEach(dataPoints) { item in
LineMark(
x: .value("Date", item.date),
y: .value("Value", item.value),
series: .value("Series", "Test")
)
}
}
.frame(height: 200)
.chartScrollableAxes(.horizontal)
.chartYAxis(.hidden)
.chartXScale(domain: startDate...endDate) // one year possibility to scroll back
.chartXVisibleDomain(length: 3600 * 3) // 3 hours visible on screen
.onAppear {
Task {
dataPoints = await TestData().generate(startDate: startDate)
}
}
}
}
I would be grateful for any insights or suggestions on how to improve it or if it's planned to be improved in the future.
Currently, I use UIKit CollectionView where we split the graph into smaller chunks of the graph and we present the SwiftUI Chart content in the cells, so we use the scrolling offered there. I wonder if it's possible to use native SwiftUI for such a scenario so that later on we could also implement some kind of lazy loading of the data as the user scrolls into the past.