DavidPiper94

private var series: [AXDataSeriesDescriptor] {
    // 1
    let yValuesSeries1 = [4.0, 5.0, 6.0, 3.0, 2.0, 1.0, 1.0, 3.0, 6.0, 9.0]
    let dataPointsSeries1 = yValuesSeries1.enumerated().map { index, yValue in
        AXDataPoint(x: Double(index), y: yValue)
    }

    // 2
    let yValuesSeries2 = [6.0, 5.0, 4.0, 7.0, 8.0, 9.0, 9.0, 7.0, 4.0, 1.0]
    let dataPointsSeries2 = yValuesSeries2.enumerated().map { index, yValue in

DavidPiper94

// 1
var accessibilityChartDescriptor: AXChartDescriptor? {
    // 2
    get {
        AXChartDescriptor(
            title: "Example Graph",
            summary: "This graph shows example data.",
            xAxis: xAxis,
            yAxis: yAxis,
            series: series

DavidPiper94

private var series: [AXDataSeriesDescriptor] {
    // 1
    let yValuesSeries = [4.0, 5.0, 6.0, 3.0, 2.0, 1.0, 1.0, 3.0, 6.0, 9.0]
    let dataPointsSeries = yValuesSeries.enumerated().map { index, yValue in
        AXDataPoint(x: Double(index), y: yValue)
    }

    // 2
    return [
        AXDataSeriesDescriptor(

DavidPiper94

private var yAxis: AXNumericDataAxisDescriptor {
    AXNumericDataAxisDescriptor(
        title: "The y axis",
        range: (0...9),
        gridlinePositions: [],
        valueDescriptionProvider: { (value: Double) -> String in
            "\(value)"
        }
    )
}

DavidPiper94

private var xAxis: AXNumericDataAxisDescriptor {
    // 1
    AXNumericDataAxisDescriptor(
        title: "The x axis",
        // 2
        range: (0...9),
        // 3
        gridlinePositions: [],
        // 4
        valueDescriptionProvider: { (value: Double) -> String in

DavidPiper94

class HistoryService {
  
    // ...

    // 6
    func record(command: Command) {
        // Remove all undone actions at top of list.
        history = Array(history.drop { $0.isUndone} )
        // Prepend command.
        history = [command] + history

DavidPiper94

class HistoryService {

    // ...

    // 4
    func registerUndoFor(command: Command) {
        undoManager.registerUndo(withTarget: self) { selfTarget in
            command.isUndone = true
            command.reverse()
            selfTarget.registerRedoFor(command: command)

DavidPiper94

// 1
func redButtonPressed(_ sender: UIButton) {
    recordColorChangeCommand(newColor: .red)
}

// 2
func recordColorChangeCommand(newColor: UIColor) {
    let currentColor = colorView.backgroundColor
    let command = Command(
        execute: { self.colorView.backgroundColor = newColor },

DavidPiper94

class HistoryService {

    // 1
    let undoManager = UndoManager()
    var history = [Command]()

    // 2
    var canUndo: Bool { undoManager.canUndo }
    func undo() {
        guard canUndo else { return }

DavidPiper94

class Command {
    var isUndone: Bool
    let execute: () -> Void
    let reverse: () -> Void

    init(execute: @escaping () -> Void, reverse: @escaping () -> Void) {
        isUndone = false
        self.execute = execute
        self.reverse = reverse
    }