1# Swift Charts Accessibility, Fallback, and Resources
2 
3## Table of Contents
4 
5- [Accessibility](#accessibility)
6  - [Meaningful Labels](#meaningful-labels)
7  - [Custom Audio Graphs](#custom-audio-graphs)
8- [Composite Example](#composite-example)
9- [Fallback Strategies](#fallback-strategies)
10  - [Version Breakdown](#version-breakdown)
11- [WWDC Sessions](#wwdc-sessions)
12- [Summary Checklist](#summary-checklist)
13 
14---
15 
16## Accessibility
17 
18Swift Charts provides built-in accessibility support. VoiceOver users get three rotor actions automatically:
19 
20- **Describe Chart** — overview of axes and data series
21- **Audio Graph** — sonification where pitch represents data values
22- **Chart Detail** — interactive mode for exploring individual data points
23 
24### Meaningful Labels
25 
26**Always** use clear, descriptive strings in `.value(_, _)` calls. These labels are read by VoiceOver and used in the Audio Graph.
27 
28```swift
29// Good — descriptive labels
30LineMark(
31    x: .value("Date", entry.date),
32    y: .value("Daily Steps", entry.count)
33)
34 
35// Bad — generic labels
36LineMark(
37    x: .value("X", entry.date),
38    y: .value("Y", entry.count)
39)
40```
41 
42### Custom Audio Graphs
43 
44For advanced accessibility, conform your chart view to `AXChartDescriptorRepresentable` and implement `makeChartDescriptor()`. Attach it with `.accessibilityChartDescriptor(self)`.
45 
46```swift
47struct StepsChart: View, AXChartDescriptorRepresentable {
48    let steps: [DailySteps]
49 
50    var body: some View {
51        Chart(steps) { day in
52            LineMark(x: .value("Date", day.date), y: .value("Steps", day.count))
53        }
54        .accessibilityChartDescriptor(self)
55    }
56 
57    func makeChartDescriptor() -> AXChartDescriptor {
58        guard let first = steps.first, let last = steps.last else {
59            return AXChartDescriptor(title: "Daily Step Count", summary: nil,
60                xAxis: AXNumericDataAxisDescriptor(title: "Date", range: 0...1, gridlinePositions: []) { "\($0)" },
61                yAxis: AXNumericDataAxisDescriptor(title: "Steps", range: 0...1, gridlinePositions: []) { "\($0)" },
62                additionalAxes: [], series: [])
63        }
64        let xAxis = AXDateDataAxisDescriptor(
65            title: "Date", range: first.date...last.date, gridlinePositions: [])
66        let yAxis = AXNumericDataAxisDescriptor(
67            title: "Steps", range: 0...Double(steps.map(\.count).max() ?? 0),
68            gridlinePositions: []) { "\(Int($0)) steps" }
69        let series = AXDataSeriesDescriptor(
70            name: "Daily Steps", isContinuous: true,
71            dataPoints: steps.map { .init(x: $0.date, y: Double($0.count)) })
72        return AXChartDescriptor(title: "Daily Step Count", summary: nil,
73            xAxis: xAxis, yAxis: yAxis, additionalAxes: [], series: [series])
74    }
75}
76```
77 
78## Composite Example
79 
80A scrollable bar chart with range selection combining multiple iOS 17+ APIs:
81 
82```swift
83@State private var selectedRange: ClosedRange<Int>?
84 
85Chart(weeklyRevenue) { week in
86    BarMark(x: .value("Week", week.index), y: .value("Revenue", week.revenue))
87        .foregroundStyle(by: .value("Region", week.region))
88}
89.chartScrollableAxes(.horizontal)
90.chartXVisibleDomain(length: 8)
91.chartXSelection(range: $selectedRange)
92.chartXAxis {
93    AxisMarks(values: .stride(by: 1)) {
94        AxisGridLine()
95        AxisValueLabel { Text("W\($0.as(Int.self) ?? 0)") }
96    }
97}
98```
99 
100## Fallback Strategies
101 
102Gate advanced APIs with `#available` and provide a fallback chart without the gated features. Because chart modifiers like `.chartXSelection` change the return type, you must duplicate the entire `Chart` — you cannot conditionally apply the modifier:
103 
104### Version Breakdown
105 
106- iOS 16+: `Chart`, custom axes, scales, `BarMark`, `LineMark`, `AreaMark`, `PointMark`, `RectangleMark`, `RuleMark`, `ChartProxy`, `chartOverlay`, `chartBackground`
107- iOS 17+: `SectorMark`, `chartXSelection`, `chartYSelection`, `chartAngleSelection`, `chartScrollableAxes`, visible-domain scrolling APIs, `chartGesture`
108- iOS 18+: `AreaPlot`, `BarPlot`, `LinePlot`, `PointPlot`, `RectanglePlot`, `RulePlot`, `SectorPlot`, function plotting
109- iOS 26+: `Chart3D`, `SurfacePlot`, Z-axis marks, 3D camera and pose APIs
110 
111## WWDC Sessions
112 
113- [Hello Swift Charts](https://developer.apple.com/videos/play/wwdc2022/10136/) (WWDC 2022) — introduction to the framework
114- [Swift Charts: Raise the bar](https://developer.apple.com/videos/play/wwdc2022/10137/) (WWDC 2022) — marks, composition, customization
115- [Design an effective chart](https://developer.apple.com/videos/play/wwdc2022/110340/) (WWDC 2022) — chart design principles
116- [Design app experiences with charts](https://developer.apple.com/videos/play/wwdc2022/110342/) (WWDC 2022) — integrating charts into app UX
117- [Explore pie charts and interactivity in Swift Charts](https://developer.apple.com/videos/play/wwdc2023/10037/) (WWDC 2023) — SectorMark, selection, scrolling
118- [Swift Charts: Vectorized and function plots](https://developer.apple.com/videos/play/wwdc2024/10155/) (WWDC 2024) — LinePlot, AreaPlot, function plotting
119- [Bring Swift Charts to the third dimension](https://developer.apple.com/videos/play/wwdc2025/313/) (WWDC 2025) — Chart3D, SurfacePlot, 3D marks
120 
121## Summary Checklist
122 
123- [ ] `import Charts` is present in files using chart types
124- [ ] Deployment target matches the APIs used (`Chart` on iOS 16+, selection and `SectorMark` on iOS 17+, plot types on iOS 18+, `Chart3D` on iOS 26+)
125- [ ] Chart data models use `Identifiable` (or `Chart(data, id:)` is provided)
126- [ ] All chart families are represented with the correct mark type
127- [ ] Axes use `AxisMarks` when default ticks are too dense or unclear
128- [ ] `chartXScale` or `chartYScale` is set when fixed domains matter
129- [ ] Chart-wide modifiers are applied to `Chart`, not individual marks
130- [ ] `foregroundStyle(by:)` used for categorical series (not manual per-mark colors)
131- [ ] Single-value selection uses `chartXSelection(value:)` or `chartYSelection(value:)`
132- [ ] Range selection uses `chartXSelection(range:)` or `chartYSelection(range:)`
133- [ ] `SectorMark` selection uses `chartAngleSelection(value:)`
134- [ ] iOS 17+, iOS 18+, and iOS 26+ APIs are guarded with `#available`
135- [ ] `.value()` labels are descriptive for VoiceOver and Audio Graph accessibility
136