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ChartModel is an ObservableObject that holds all data and configuration for a chart. Pass it to ChartView and any change you make to the model — data, selection, axis attributes, or series colors — immediately re-renders the chart. 
let model = ChartModel(
    chartType: .line,
    data: [[200, 170, 165, 143, 166, 112, 110],
           [150, 120, 130, 135, 120, 138, 137]],
    titlesForCategory: [["Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul"]]
)

ChartView(model)
    .frame(width: 300, height: 200)

​
Initializers

Two public convenience initializers cover nearly all use cases.

​
Standard 2D init (most chart types)

Use this initializer for line, column, bar, area, combo, stacked column, stacked bar, waterfall, donut, and micro charts. 
public convenience init(
    chartType: ChartType,
    data: [[Double?]],
    titlesForCategory: [[String?]]? = nil,
    colorsForCategory: [Int: [Int: Color]]? = nil,
    titlesForAxis: [ChartAxisId: String]? = nil,
    labelsForDimension: [[String?]]? = nil,
    numberOfGridlines: Int = 3,
    selectionRequired: Bool = false,
    selectionMode: ChartSelectionMode = .single,
    selections: [Int: [Int]]? = nil,
    userInteractionEnabled: Bool = false,
    selectionEnabled: Bool = false,
    centerPosition: CGPoint? = nil,
    scaleX: CGFloat = 1.0,
    scaleY: CGFloat = 1.0,
    scaleXEnabled: Bool = false,
    scaleYEnabled: Bool = false,
    readableScaleEnabled: Bool = true,
    snapToPoint: Bool = false,
    seriesAttributes: [ChartSeriesAttributes]? = nil,
    categoryAxis: ChartCategoryAxisAttributes? = nil,
    numericAxis: ChartNumericAxisAttributes? = nil,
    secondaryNumericAxis: ChartNumericAxisAttributes? = nil,
    xAxisLabelsPosition: XAxisLabelsPosition = .fixedBottom,
    indexOfStockSeries: Int = 0,
    indexesOfSecondaryValueAxis: [Int]? = nil,
    indexesOfColumnSeries: [Int]? = nil,
    indexesOfTotalsCategories: [Int]? = nil,
    numericAxisLabelFormatHandler: NumericAxisLabelFormatHandler? = nil
)

​
3D init (bubble, scatter, stock)

Use this initializer when each data point has three dimensions — for example [x, y, radius] for a bubble chart. 
public convenience init(
    chartType: ChartType,
    data3d: [[[Double?]]],
    // ... same options as above
)
For bubble charts, supply values in [x, y, radius] order per data point. The initializer reorders them internally.

​
Parameters

​
chartType
ChartType
required
The chart type to render. See Chart types for the full list of values.
​
data
[[Double?]]
required
A two-dimensional array structured as series → categories. The outer array contains one element per series; each inner array contains the values for that series, one per category. Use nil for missing data points — the chart will render a gap.
// Two series, seven categories each
data: [
    [nil, 220, nil, 250, 200, nil, 230],  // series 0
    [160, nil, 130, 170, nil, 190, 180]   // series 1
]
​
titlesForCategory
[[String?]]?
default:"nil"
Labels for the category axis. The outer array corresponds to series; in practice you usually supply a single inner array that applies to all series.
titlesForCategory: [["Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul"]]
​
colorsForCategory
[Int: [Int: Color]]?
default:"nil"
Per-category color overrides, keyed by [seriesIndex: [categoryIndex: Color]]. Overrides the color from seriesAttributes for the specified categories.
colorsForCategory: [0: [2: .red, 5: .orange]]
​
titlesForAxis
[ChartAxisId: String]?
default:"nil"
Axis title strings keyed by ChartAxisId. Use .x, .y, .category, or .dual.
titlesForAxis: [.x: "Month", .y: "Revenue (USD)"]
​
labelsForDimension
[[String?]]?
default:"nil"
Custom labels rendered on individual data points, in the same series × category layout as data. Useful for annotating specific values.
​
numberOfGridlines
Int
default:"3"
Number of gridlines drawn on the numeric axis. Constrained to the range 2–20.
​
selectionMode
ChartSelectionMode
default:".single"
Controls which plot items are selected when the user taps.
  • .single — selects one value in the active series and category.
  • .all — selects one value per series for the tapped category.
  • .multiple — multiple independent selections (donut charts only; set automatically).
​
selections
[Int: [Int]]?
default:"nil"
Initial selection state. The dictionary maps seriesIndex to an array of categoryIndex values.
// Pre-select categories 0–6 in series 0
selections: [0: [0, 1, 2, 3, 4, 5, 6]]

// Select category 0 in both series (selectionMode: .all)
selections: [0: [0], 1: [0]]
​
userInteractionEnabled
Bool
default:"false"
Enables pan, pinch-to-zoom, and drag gestures. Set to false when using the chart in an iOS Widget.
​
selectionEnabled
Bool
default:"false"
Enables tap and two-finger long-press selection gestures independently of userInteractionEnabled.
​
seriesAttributes
[ChartSeriesAttributes]?
default:"nil"
Per-series styling — colors, line width, point attributes. See Customizing charts for details.
​
categoryAxis
ChartCategoryAxisAttributes?
default:"nil"
Style and behavior attributes for the category axis (X axis for most chart types, Y axis for bar charts).
​
numericAxis
ChartNumericAxisAttributes?
default:"nil"
Style and behavior attributes for the primary numeric axis (Y axis for most chart types, X axis for bar charts).
​
secondaryNumericAxis
ChartNumericAxisAttributes?
default:"nil"
Attributes for the secondary numeric axis. Only applicable to .line, .area, and .combo chart types.
​
snapToPoint
Bool
default:"false"
When true, the chart snaps to the nearest data point while the user drags.
​
indexesOfSecondaryValueAxis
[Int]?
default:"nil"
Series indexes assigned to the secondary Y axis. Only applies to .line, .area, and .combo charts.
​
indexesOfColumnSeries
[Int]?
default:"nil"
For .combo charts, the series indexes that render as columns. All other series render as lines.
​
indexesOfTotalsCategories
[Int]?
default:"nil"
For .waterfall charts, the category indexes that represent totals. If the corresponding value is nil in data, the chart computes the running total automatically.
​
numericAxisLabelFormatHandler
NumericAxisLabelFormatHandler?
default:"nil"
A closure that formats numeric axis label values. Use this for custom units or precision.

​
Examples

​
Line chart with two series

let model = ChartModel(
    chartType: .line,
    data: [
        [nil, 220, nil, 250, 200, nil, 230],
        [160, nil, 130, 170, nil, 190, 180]
    ],
    titlesForCategory: [["Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul"]],
    titlesForAxis: [.x: "Month", .y: "Units"],
    numberOfGridlines: 4,
    selectionMode: .all,
    selectionEnabled: true
)

ChartView(model)
    .frame(width: 360, height: 220)

​
Donut chart

Donut charts use a single series and a single category per segment. The selectionMode is automatically set to .multiple for donut charts. 
let model = ChartModel(
    chartType: .donut,
    data: [[1550, 1120, 830, 420]],
    titlesForCategory: [["Q1", "Q2", "Q3", "Q4"]],
    colorsForCategory: [
        0: [
            0: Color(hex: "#E57373"),
            1: Color(hex: "#FFB74D"),
            2: Color(hex: "#81C784"),
            3: Color(hex: "#64B5F6")
        ]
    ]
)

ChartView(model)
    .frame(width: 240, height: 240)

​
Waterfall chart with totals

let model = ChartModel(
    chartType: .waterfall,
    data: [[1200, -300, 450, -180, nil]],
    titlesForCategory: [["Start", "Costs", "Revenue", "Taxes", "Net"]],
    indexesOfTotalsCategories: [4] // index 4 is computed as running total
)

ChartView(model)
    .frame(width: 360, height: 220)

​
Observing selection changes

Subscribe to selectionDidChangePublisher using Combine to react to user-driven selection updates. 
import Combine

var cancellables: Set<AnyCancellable> = []

model.selectionDidChangePublisher
    .receive(on: RunLoop.main)
    .sink { selections in
        guard let selections else {
            print("No selection")
            return
        }
        for (seriesIndex, categoryIndexes) in selections {
            print("Series \(seriesIndex), categories: \(categoryIndexes)")
        }
    }
    .store(in: &cancellables)
The selectionDidChangePublisher publishes only when the user interacts with the chart. Setting model.selections programmatically does not trigger the publisher.

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