swiftswiftuiswiftui-charts

Swift Charts' chartXVisibleDomain hangs or crashes


If I use the following Swift Charts Chart anywhere (Xcode Simulator, Playground, etc.) it hangs or crashes. As soon as I remove the chartXVisibleDomain modifier everything works. Is anybody else experiencing the same issue and/or knows how to fix it? I'm on Xcode Version 15.0 (15A240d).

import SwiftUI
import Charts

struct ContentView: View {
    
    let data: [(day: Date, value: Int)] = [
        (Calendar.current.date(byAdding: .day, value: 0,   to: .now)!, 1),
        (Calendar.current.date(byAdding: .day, value: -1,  to: .now)!, 2),
        (Calendar.current.date(byAdding: .day, value: -3,  to: .now)!, 3),
        (Calendar.current.date(byAdding: .day, value: -10, to: .now)!, 4),
        (Calendar.current.date(byAdding: .day, value: -20, to: .now)!, 5)
    ]
    
    var body: some View {
        Chart(data, id: \.day) { (day, value) in
            BarMark(
                x: .value("Date", day, unit: .day),
                y: .value("Value", value)
            )
        }
        .chartXVisibleDomain(length: 2)
    }
}

Solution

  • By trial and error, I found that the number passed to chartXVisibleDomain in this case should be in seconds. This kind of makes sense, since Date is kind of like a wrapper around timeIntervalSince1970, which is in seconds.

    The app hangs probably because you are drawing a really really wide chart - you are saying you only want to see 2 seconds at a time, of the whole 20-day data.

    You can do:

    .chartXVisibleDomain(length: 86400*2) // 86400 seconds is 24 hours
    

    instead.