Swift Charts

Use this guide when implementing or modifying chart/data visualization features.

Framework

import Charts

Basic Chart Container

Chart {
    ForEach(data) { item in
        BarMark(
            x: .value("Category", item.category),
            y: .value("Value", item.value)
        )
    }
}

Mark Types

Color Coding

BarMark(x: .value("Day", item.day), y: .value("Count", item.count))
    .foregroundStyle(by: .value("Category", item.category))

Axis Customization

Chart { ... }
    .chartXAxis {
        AxisMarks(values: .stride(by: .day, count: 4)) { value in
            AxisValueLabel(format: .dateTime.day().month())
        }
    }
    .chartYAxis {
        AxisMarks { value in
            AxisGridLine()
            AxisValueLabel()
        }
    }

Scrollable Charts (large datasets)

Chart { ... }
    .chartScrollableAxes(.horizontal)
    .chartXVisibleDomain(length: 7)  // Show 7 items at a time

Rules

• Extract Chart into a separate computed property — avoid body complexity
• Use AppTheme.Colors.* for chart colors, not hardcoded values
• Prefer BarMark for discrete categories, LineMark for continuous trends
• Add .chartYScale(domain: 0...10) when the scale should be fixed