SwiftUI

SwiftUI is Apple’s declarative UI framework. tswift renders it without a Swift toolchain, LLVM, or native compilation: the interpreter instantiates a View, runs body, produces a host-neutral UIIR view tree, diffs it into a patch stream, and a dependency-free host applies those patches to real UI.

Current status: foundational tiers + breadth shipped. The Counter slice (v1) plus Tiers 2–5 — composition, dynamic collections, input controls, and observation — are implemented and gated by deterministic goldens. On top of that, the C1–C7 breadth batches widened the surface: universal text/styling modifiers, layout arguments, structural containers (Group/Divider/ ScrollView), decoration (border/shadow/clipShape), content views (Label/Image/ProgressView), lazy stacks & grids, Form, and control styling — each landed in all three appliers (runtime, web, iOS) with goldens. Async (Tier 6), GeometryReader (Tier 7), and navigation (Tier 8) are not started.

Legend: ✅ Implemented · 🟡 Partial · ⬜ Missing · 🚫 Out of scope. The surface count below tracks individual API members across the iOS SDK SwiftUI interface — it is much lower than the tier roadmap suggests because each shipped view exposes many initializers and modifiers we don’t need yet. The functional coverage — enough to render and interact with real view hierarchies — is further along, as the tiers below show. Generated by python3 tools/framework-inventory/coverage.py --framework swiftui --emit-json.

How it renders

    
flowchart LR
  src["Swift View\nsource"]
  interp["Interpreter\n+ tswift-swiftui\nbuiltins"]
  tree["Render-node tree\n(owns @State,\nkeyed identity)"]
  uiir["UIIR\nview tree"]
  diff["Rust diff\nengine"]
  host["Host applier\n(web + iOS)"]

  src --> interp --> tree --> uiir --> diff --> host
  host -- "events" --> interp

  style src   fill:#1a0d2e,stroke:#a855f7,color:#eeeef5
  style host  fill:#0d2e1a,stroke:#34c759,color:#eeeef5

  

The same patch protocol drives two hosts: the web <swiftui-canvas> custom element, and a native iOS SwiftUI applier used for screenshot verification.

Tier roadmap

Tier 5 is partial: observation is implemented; @Environment(\.keyPath) is the one deferred item.

Verification

Every slice is checked by an autonomous loop — no Apple toolchain required to gate a change.

Layer D runs both halves locally today: a native UiirRenderer SwiftPM package builds real SwiftUI from the UIIR fixtures and snapshots them, and a Playwright harness drives the <swiftui-canvas> element through the same mount → applyPatches loop. Both capture a device × appearance matrix (iPhone + iPad, light + dark), so token/CSS drift between the web and native renderers is surfaced side by side. Perceptual-diff tooling and a CI job are the remaining pieces.

What you can run now

• SwiftUI Views built from the implemented views, controls, and shapes above
• @State-driven interaction (the Counter and demo tabs)
• ObservableObject / @StateObject shared model state
• Dynamic List/ForEach with add/remove/reorder

Try it in the Playground →