Bring accessibility to charts in your app

10:47 - Chart Model

class ChartView: UIView {
    let model: ChartModel

    func drawChart() {
        // ...
    }
}

struct ChartModel {
    let title: String
    let dataPoints: [DataPoint]
        
    struct DataPoint {
        let name: String
        let x: Double
        let y: Double
    }
}

10:48 - ChartView

extension ChartView {
    public override var accessibilityContainerType: UIAccessibilityContainerType { … }
    public override var accessibilityLabel: String? { … }

    public override var accessibilityElements: [Any]? {
        get {
            return model.dataPoints.map { point in
                let axElement = UIAccessibilityElement(accessibilityContainer: self)
                axElement.accessibilityValue = "\(point.x) cups, \(point.y) lines of code"
                axElement.accessibilityFrameInContainerSpace = frameRect(for: point)
                return axElement
            }
        }
        set {}
    }
  
 private func frameRect(for dataPoint: DataPoint) -> CGRect {

14:23 - Basic chart definition example

struct ChartModel {
    let title: String
    let summary: String
    let xAxis: Axis
    let yAxis: Axis
    let data: [DataPoint]

    struct Axis {
        let title: String
        let range: ClosedRange<Double>
    }
    
    struct DataPoint {
        let name: String
        let x: Double
        let y: Double
    }
}

15:08 - Enabling Audio Graphs

import Accessibility

extension ChartView: AXChart {

public var accessibilityChartDescriptor: AXChartDescriptor? {
    get {
    }
    set {}
    }
}

15:35 - Chart Descriptor- Basic

public var accessibilityChartDescriptor: AXChartDescriptor? {
    get {
        let xAxis = AXNumericDataAxisDescriptor( … ) 
        let yAxis = AXNumericDataAxisDescriptor(title: model.yAxis.title,
                                                range: model.yAxis.range,
                                                gridlinePositions:[],
                                                valueDescriptionProvider: { value in
            return "\(value) lines of code"
        })
    }
    set {}
}

16:55 - Chart Descriptor- Continued

public var accessibilityChartDescriptor: AXChartDescriptor? {
    get {
        let xAxis = AXNumericDataAxisDescriptor( … )
        let yAxis = AXNumericDataAxisDescriptor( … )
        let series = AXDataSeriesDescriptor( … )
        return AXChartDescriptor(title: model.title,
                                 summary: model.summary,
                                 xAxis: xAxis,
                                 yAxis: yAxis,
                                 additionalAxes: [],
                                 series: [series])
    }
    set {}
}