swift

Coding rules for Swift, Apple's programming language, including SwiftUI for app interfaces and async/await for tasks that run over time. It also covers data types, error handling, and shared state.

In plain words
What is it for?
Building Swift and SwiftUI apps, modeling application state, structuring asynchronous work, protecting shared mutable data with actors, handling errors, and organizing views.
Why use it?
It gives an agent consistent patterns for writing and reviewing Swift code. The rules help avoid unsafe optional handling and common problems with concurrent code and UI updates.

Cursor rule

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add rules/nedcodes-ok/cursorrules-collection/swift
Clone the repo
git clone --depth 1 https://github.com/nedcodes-ok/cursorrules-collection
Per session 310 This file is loaded in full into every session.
When invoked 310 The same file — it is already loaded in full.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00310 $0.00310
Opus 5 $0.00155 $0.00155
Sonnet 5 $0.00062 $0.00062
Haiku 4.5 $0.00031 $0.00031

Measured yesterday against content hash 662f22522293, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

swift scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured yesterday.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

rules-mdc/languages/swift.mdc · 44 lines

What it actually says

Swift Cursor Rules

You are an expert Swift developer. Follow these rules:

Code Style

  • Target Swift 5.9+. Use async/await, actors, result builders
  • Follow Swift API Design Guidelines: clarity at point of use
  • Verb phrases for mutating, noun phrases for non-mutating methods
  • Use trailing closure syntax

Type System

  • Structs by default. Classes only for reference semantics
  • Use enums with associated values for state modeling
  • Use protocols for abstraction with protocol extensions
  • Generics with where clauses for constrained polymorphism

Optionals

  • guard let for early exits, if let for conditional paths
  • Use ?. and ?? to avoid force unwrapping
  • Never ! in production except IBOutlets
  • map/flatMap on optionals for transformations

Concurrency

  • async/await for all async code
  • Actors for mutable shared state
  • TaskGroup for structured concurrency
  • MainActor for UI updates

SwiftUI

  • @State for local state, @Binding for parent-child
  • @Observable over ObservableObject for new code
  • Keep views small, extract at 30+ lines
  • Environment for dependency injection

Error Handling

  • Use typed throws (Swift 5.9+) for predictable errors
  • Handle errors at appropriate level — don't catch and ignore
Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. yesterday First seen · 44 lines · 310 tokens per session scan A 662f22522293

Subscribe to this mod's changes

swift is a cursor rule published in the GitHub repository nedcodes-ok/cursorrules-collection (37 stars, last pushed 6mo ago), licensed MIT. It adds 310 tokens to every session, about $0.0015 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.