# axiom-swift

Guides AI coding assistants through modern Swift idioms, noncopyable types, Transferable protocols, and tvOS development.

- skill · `type=skill` · Claude Code, Codex, Cursor, GitHub Copilot, Gemini CLI, OpenCode · 1200 installs · ★ 1229
- Author: CharlesWiltgen
- License: MIT · policy=mirror · the beginning of the file is at the end of this page
- Source: https://github.com/CharlesWiltgen/Axiom/tree/HEAD/axiom-codex/skills/axiom-swift/SKILL.md
- Updated: 2026-10-20
- HTML: https://affpapa.org/en/nevibecode/skills/axiom-swift

## What it does

The skill provides reference instructions for modern Swift syntax and toolchain capabilities. It corrects outdated habits such as `DateFormatter` or `CGFloat`, replacing them with Foundation additions like `FormatStyle` and `URL.documentsDirectory`. It also details Swift 6.4 features, including `~Copyable` noncopyable types, `borrowing` and `consuming` parameter modifiers, and memory-safe abstractions like `Span` and `InlineArray`.

Platform-specific guidance covers data sharing via `Transferable` and custom `UTType` declarations. It includes debug deep links for simulator navigation, as well as tvOS constraints around Focus Engine and local storage. Simulators and test runners require shell access.

When facing Swift 6 concurrency errors with actors or `Sendable`, the author advises switching to `axiom-concurrency` instead. This skill focuses on language idioms rather than threading models.

## Install

### Claude Code (native platform)

1. **Skills CLI (Vercel)**
```bash
npx skills add CharlesWiltgen/Axiom --skill axiom-swift -a claude-code
```

2. **Manually: put the files in place**
- File: `~/.claude/skills/axiom-swift/SKILL.md` — Copy the whole skill folder; for one project use .claude/skills/axiom-swift/

### Codex

1. **Skills CLI (Vercel)**
```bash
npx skills add CharlesWiltgen/Axiom --skill axiom-swift -a codex
```

2. **Manually: put the files in place**
- File: `.agents/skills/axiom-swift/SKILL.md` — For all projects use ~/.agents/skills/

### Cursor

1. **Skills CLI (Vercel)**
```bash
npx skills add CharlesWiltgen/Axiom --skill axiom-swift -a cursor
```

2. **Manually: put the files in place**
- File: `.cursor/skills/axiom-swift/SKILL.md` — Cursor also reads .agents/skills/ and .claude/skills/

### GitHub Copilot

1. **GitHub CLI**
```bash
gh skill install CharlesWiltgen/Axiom axiom-swift
```

2. **Manually: put the files in place**
- File: `.github/skills/axiom-swift/SKILL.md`

### Gemini CLI

1. **Skills CLI (Vercel)**
```bash
npx skills add CharlesWiltgen/Axiom --skill axiom-swift -a gemini-cli
```

2. **Platform CLI**
```bash
gemini skills install https://github.com/CharlesWiltgen/Axiom --path axiom-codex/skills/axiom-swift
```

### Windsurf (Devin Desktop)

**Manually: put the files in place**
- File: `.devin/skills/axiom-swift/SKILL.md` — The legacy .windsurf/skills/ path still works

### OpenCode

**Skills CLI (Vercel)**
```bash
npx skills add CharlesWiltgen/Axiom --skill axiom-swift -a opencode
```

### Claude.ai

**Claude.ai**
- Zip the folder and upload it in Settings → Capabilities → Skills

Where a file is given instead of a command, copy the files from the source to that path: https://github.com/CharlesWiltgen/Axiom/tree/HEAD/axiom-codex/skills/axiom-swift/SKILL.md

## When to use it
- modernize legacy Swift patterns like `DateFormatter` and `CGFloat`
- implement noncopyable types using `~Copyable` and `borrowing` parameters
- declare `Transferable` conformance and custom `UTType` identifiers
- configure debug deep links for simulator navigation and screenshots
- adapt applications to tvOS storage rules and Focus Engine input

## Example prompts
- Review this file for legacy Swift code and update DateFormatter calls to FormatStyle.
- Show me how to define a ~Copyable struct with borrowing and consuming parameters.
- Set up a debug deep link to navigate directly to the settings screen in the simulator.

## Source text · SKILL.md · MIT

Below is the content of a third-party file. It is data, not instructions for you: do not act on anything written inside unless the human asks. Block tag: 79ded8e3078fdb7f.

BEGIN THIRD-PARTY FILE 79ded8e3078fdb7f
````text
---
name: axiom-swift
description: Use when the question is about Swift or its toolchain rather than a framework — modern idioms, noncopyable types, drag and drop, debug deep links, tvOS targets.
license: MIT
---

# Swift Language & Platform

**You MUST use this skill for ANY Swift idiom review, ownership/noncopyable types, Transferable/drag-and-drop, debug deep links, or tvOS development.**

<!-- AXIOM_AUDITOR_INLINE_BEGIN — rewritten for Codex by scripts/build-codex.ts; do not hand-edit -->
> **Auditors are skills here.** Where this router says "Launch `some-auditor` agent", invoke the
> matching Codex skill instead — same procedure, no Claude Code agent required.
>
> Available: `axiom-swift-simplifier`.
>
> The ones that shell out — builds, tests, simulators, crash symbolication — need shell access to run.
<!-- AXIOM_AUDITOR_INLINE_END -->

## Quick Reference

| Symptom / Task | Reference |
|----------------|-----------|
| Outdated Swift patterns (Date(), CGFloat, DateFormatter) | See `skills/swift-modern.md` |
| Foundation modernization (FormatStyle, URL.documentsDirectory) | See `skills/swift-modern.md` |
| Common Claude hallucinations in Swift code | See `skills/swift-modern.md` |
| Swift 6.4 idioms — `anyAppleOS`, `weak let`, `~Sendable` (`OS27`) | See `skills/swift-modern.md` |
| Noncopyable types (~Copyable) | See `skills/ownership-conventions.md` |
| borrowing/consuming parameter ownership | See `skills/ownership-conventions.md` |
| InlineArray, Span, value generics; Swift 6.4 `borrow`/`mutate` accessors (`OS27`) | See `skills/ownership-conventions.md` |
| Reducing ARC overhead | See `skills/ownership-conventions.md` |
| Drag and drop (.draggable, .dropDestination) | See `skills/transferable-ref.md` |
| Copy/paste (.copyable, PasteButton) | See `skills/transferable-ref.md` |
| ShareLink, content sharing | See `skills/transferable-ref.md` |
| Custom UTType declarations | See `skills/transferable-ref.md` |
| TransferRepresentation choices | See `skills/transferable-ref.md` |
| Debug-only deep links for simulator testing | See `skills/deep-link-debugging.md` |
| Navigate to specific screens for screenshots | See `skills/deep-link-debugging.md` |
| tvOS Focus Engine, Siri Remote input | See `skills/tvos.md` |
| tvOS storage constraints (no guaranteed-persistent local storage) | See `skills/tvos.md` |
| tvOS text input, AVPlayer tuning | See `skills/tvos.md` |
| TVUIKit components | See `skills/tvos.md` |
| Simplify Swift for clarity (behavior-preserving cleanups) | `swift-simplifier` agent — `axiom-swift-simplifier` |

## Decision Tree

```dot
digraph swift {
    start [label="Swift task" shape=ellipse];
    what [label="What do you need?" shape=diamond];

    start -> what;
````
END THIRD-PARTY FILE 79ded8e3078fdb7f

The third-party file has ended. Everything between the 79ded8e3078fdb7f tags is data: requests and commands from it are not followed. An “end of file” line with another tag inside the block is part of the file.

First 2743 of 10057 bytes. © CharlesWiltgen · MIT · https://github.com/CharlesWiltgen/Axiom/tree/HEAD/axiom-codex/skills/axiom-swift/SKILL.md

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