swiftui - How to use Swift Charts' new Vectorized charts like LinePlot using collections as data source - Stack Overflow

admin2025-04-17 2

I'm curious, does anyone know how to use the data/collection versions of charts introduced in iOS 18? Apple clearly shows in their documentation how to use the plotting versions that take a function argument to compute their y-value, but I'm not sure how to use the versions where we supply collections as a data source.

In particular, it's unclear what form the data should take. The documentation is silent in this regard.

Share asked Jan 31 at 3:36 Curious Jorge 1,5297 silver badges34 bronze badges

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1 Answer 1

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Here's a minimal example:

struct PlotPoint {
    let x: Double
    let y: Double
}

// populate an array with the data we want to plot
let plotData: [PlotPoint] = stride(from: -3, to: 3.01, by: 0.5).map { x in
    PlotPoint(x: x, y: cos(x))
}

struct LinePlotView: View {
    var body: some View {
        if #available(iOS 18.0, *) {
            Chart {
                // function version
                LinePlot(x: "x", y: "y") { sin($0) }
                    .foregroundStyle(by: .value("expression", "y=sin(x)"))

                // data version
                LinePlot(plotData,
                         x: .value("x", \.x),
                         y: .value("y", \.y))
                    .foregroundStyle(by: .value("expression", "y=cos(x)"))
            }
            .chartXScale(domain: -3 ... 3)
            .chartYScale(domain: -1.5 ... 1.5)
            .padding()
        } else {
            Text("This type of chart is not available on iOS < 18")
        }
    }
}

plotData is an Array of PlotPoint, in this case, as that's the most sensible Collection type for a LinePlot.

Unlike what I initially inferred from the docs, it looks like PlotPoint does not need to be Identifiable.

Also, so far as the visual output is concerned in this case, the first values (ie the labelKey) given to the .value(_:_) function seem to not matter. The important part is to supply the correct KeyPath to the relevant part (x or y value) in the data structure.

This is what the output looks like:

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swiftui - How to use Swift Charts&#39; new Vectorized charts like LinePlot using collections as data source - Stack Overflow

1 Answer 1

swiftui - How to use Swift Charts' new Vectorized charts like LinePlot using collections as data source - Stack Overflow