solid-swift

Original：🇺🇸 English

Translated

SOLID principles for Swift 6 and SwiftUI (iOS 26+). Files < 150 lines, protocols separated, @Observable, actors, Preview-driven development. Features Modular MANDATORY.

2installs

Sourcefusengine/agents

Added on2026-02-28

NPX Install

npx skill4agent add fusengine/agents solid-swift

SKILL.md Content

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SOLID Swift - Apple Best Practices 2026

Agent Workflow (MANDATORY)

Before ANY implementation, use

TeamCreate

to spawn 3 agents:

fuse-ai-pilot:explore-codebase - Analyze existing architecture
fuse-ai-pilot:research-expert - Verify Swift/Apple docs via Apple Docs MCP + Context7
XcodeBuildMCP - Build validation after code changes. Then run fuse-ai-pilot:sniper.

DRY - Reuse Before Creating (MANDATORY)

Before writing ANY new code:

Grep the codebase for similar protocols, services, or logic

Check shared locations:

Core/Extensions/

,

Core/Utilities/

,

Core/Protocols/

If similar code exists -> extend/reuse instead of duplicate
If code will be used by 2+ features -> create it in
```
Core/
```
directly

Architecture (Features Modular MANDATORY)

Layer	Location	Max Lines
Views	`Features/[Feature]/Views/`	80
ViewModels	`Features/[Feature]/ViewModels/`	100
Services	`Features/[Feature]/Services/`	100
Protocols	`Features/[Feature]/Protocols/`	30
Shared	`Core/{Models,Protocols,Services,Extensions,Utilities}/`	-

NEVER use flat
Sources/
structure - always
Features/[Feature]/

Critical Rules (MANDATORY)

Rule	Value
File limit	150 lines (split at 120)
ViewModels	`@MainActor @Observable`
Protocols	`Features/[Feature]/Protocols/` or `Core/Protocols/` ONLY
Models	`Sendable` structs
Documentation	`///` on all public APIs
Previews	Every View MUST have `#Preview`

Reference Guide

Concepts

Topic	Reference	When to consult
SOLID Overview	solid-principles.md	Quick reference all principles
SRP	single-responsibility.md	Fat views/VMs, splitting files
OCP	open-closed.md	Adding providers, extensibility
LSP	liskov-substitution.md	Protocol contracts, testing
ISP	interface-segregation.md	Fat protocols, splitting
DIP	dependency-inversion.md	Injection, testing, mocking
Concurrency	concurrency-patterns.md	Actors, @MainActor, Sendable
Anti-Patterns	anti-patterns.md	Code smells detection

Templates

Template	When to use
view.md	SwiftUI View with subviews and #Preview
viewmodel.md	@Observable ViewModel with @MainActor
service.md	API Service, Mock, Cache actor
protocol.md	Service protocol, CQRS, Auth
model.md	Model, DTO, Error, Enum

Forbidden

Anti-Pattern	Fix
Files > 150 lines	Split at 120
Protocols in impl files	Move to `Protocols/` directory
`ObservableObject`	Use `@Observable`
Completion handlers	Use `async/await`
Missing `#Preview`	Add preview for every View
Non-Sendable in async	Use `struct` with `let`
Flat `Sources/` structure	Use `Features/[Feature]/`