Swift Charts - Scrolling performance

chart_scroll_issue.swift

import SwiftUI
import Charts

@available(iOS 16.0, *)
struct ContentView: View {
    @State private var selection: HashableItem?

    var body: some View {
        // MARK: - 1. Baseline performance test
        // Scrolling is smooth, CPU averages around 10% when scrolling
        // Scrolling occasionally shows empty cells, especially when dragging to scroll before flicking
//        List {
//            ForEach(0...100, id:\.self) { number in
//                chart
//            }
//        }
        // MARK: - 2. Navigation impact test
        // Scrolling stutters and CPU averages around 95% when scrolling
        // Rapid scrolling hangs the UI completely for a few seconds
//        NavigationSplitView {
//            List {
//                ForEach(0...100, id:\.self) { number in
//                    NavigationLink(destination: EmptyView()) {
//                        chart
//                    }
//                }
//            }
//        } detail: {
//            EmptyView()
//        }
        // MARK: - 3. Navigation by value impact test
        // Similar performance to test 2 above
        // Tapping on rows to change the selection takes roughly 3 seconds, causing the CPU to spike at 100%
        NavigationSplitView {
            List(selection: $selection) {
                ForEach(0...100, id:\.self) { number in
                    NavigationLink(value: HashableItem(value: number)) {
                        chart
                    }
                }
            }
        } detail: {
            EmptyView()
        }
    }

    var chart: some View {
        Chart {
            ForEach(Array(HealthData.ecgSample.enumerated()), id: \.element) { index, element in
                LineMark(
                    x: .value("Index", index),
                    y: .value("Unit", element)
                )
                .lineStyle(StrokeStyle(lineWidth: 3))
                .foregroundStyle([Color.red, .yellow, .pink, .green, .purple, .orange, .blue].randomElement()!.gradient)
                .interpolationMethod(.cardinal)
                .accessibilityLabel("Index")
                .accessibilityValue("\(element)")
            }
        }
        .frame(height: 150)
    }
}

struct HashableItem: Hashable {
    let value: Int
}

enum HealthData {
    static let ecgSample = [
        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    ]
}

Results from Test 3, when tapping on rows to change the selection

Result from test 3, scrolling performance

Simulator.Screen.Recording.-.iPhone.13.Pro.Max.-.2022-06-18.at.13.41.49.mp4

Raised FB10335209

Issue still exists in Xcode 14 beta 3.

Issue still exists in Xcode 14 beta 5.

Just a thing to add.. this issue persist also on real device with Version 14.0 (14A309)