An illustrative cashflow Sankey, the kind of flow SwiftSankeyDiagram renders from an app's own data.

SwiftSankeyDiagram is a small, focused SwiftUI package for drawing Sankey diagrams: flow visualizations that show how quantities move between categories. It is built to drop into an iOS or macOS app and render diagrams from data the app already owns.

The goal

Package Sankey rendering as a clean, reusable component so any SwiftUI app can visualize flows without reinventing the layout math, and without the library dictating the app’s data model.

What I built

• A SwiftUI package with a small, composable API: SankeyNode, SankeyLink, SankeyDiagram, and SankeyDiagramStyle.
• A clean boundary: the package handles only rendering, while host apps map their own types into the diagram model.
• Export to PNG and PDF through SwiftUI’s ImageRenderer.
• Swift Package Manager distribution with semantic versioning, tests, CI validation, a security policy, and contributor guidelines.
• Runnable Swift Playgrounds that demonstrate income and expense visualizations.

Design notes

• Generic over the app’s data, so the same component can serve budgets, pipelines, energy flows, or any quantity that moves between stages.
• Styling is separated from structure through SankeyDiagramStyle, so the look can change without touching the data or layout.
• Developed with an agentic engineering workflow, documented in the repository’s Codex Xcode integration guide, in the same responsible, human-in-the-loop way described on the Practices page.

Stack · Swift · SwiftUI · Swift Package Manager · iOS / macOS · MIT license

View the package on GitHub

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