Claude Code CLI - Complete iOS Development Setup Guide

A comprehensive guide for setting up Claude Code CLI with PRD-driven workflows, extended thinking (ultrathink), and planning modes optimized for Swift/SwiftUI iOS development.

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Table of Contents

1. Installation
2. Configuration Hierarchy
3. CLAUDE.md Setup for iOS Projects
4. PRD-Driven Development Workflow
5. Extended Thinking & Ultrathink
6. Plan Mode Configuration
7. XcodeBuildMCP Integration
8. Custom Slash Commands for iOS
9. Agent Skills
10. Subagents Configuration
11. Output Styles
12. Plugins System
13. Sandbox Mode & Safe Development
14. Settings & Permissions
15. Hooks for Swift Development
16. Complete Project Structure
17. Best Practices & Tips

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1. Installation

Native Installation (Recommended)

# macOS/Linux - Native installer (no Node.js required)
curl -fsSL https://claude.ai/install.sh | bash

# Or install latest version
curl -fsSL https://claude.ai/install.sh | bash -s latest

NPM Installation (Alternative)

# Global npm install (do NOT use sudo)
npm install -g @anthropic-ai/claude-code

# Migrate existing npm install to native
claude install

Authentication

# Start Claude Code and authenticate via OAuth
claude

# Or set API key environment variable
export ANTHROPIC_API_KEY="your-key-here"

Model Selection

# Use specific model at startup
claude --model claude-opus-4-5-20250929
claude --model claude-sonnet-4-5-20250929
claude --model claude-3-5-haiku-20241022

# Or set default model
export ANTHROPIC_MODEL="claude-sonnet-4-5-20250929"

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2. Configuration Hierarchy

Claude Code uses a layered configuration system where each level can override the one below:

Priority (Highest to Lowest):
├── 1. Session flags (--model, --permission-mode)
├── 2. Environment variables
├── 3. .claude/settings.local.json (local - personal, gitignored)
├── 4. .claude/settings.json (project - shared with team)
└── 5. ~/.claude/settings.json (user - global)

Configuration Scopes

Scope	Description	Storage
local	Available only to you in current project (default for MCP)	.claude/settings.local.json
project	Shared with team via git	.claude/settings.json, .mcp.json
user	Available across all your projects	~/.claude/settings.json

Key Configuration Files

File	Scope	Git Status	Purpose
~/.claude/settings.json	User	N/A	Global preferences
~/.claude/CLAUDE.md	User	N/A	Global instructions
~/.claude/skills/	User	N/A	Personal Agent Skills
~/.claude/commands/	User	N/A	Personal slash commands
.claude/settings.json	Project	Committed	Team settings
.claude/settings.local.json	Local	Gitignored	Personal overrides
.mcp.json	Project	Committed	Shared MCP servers
CLAUDE.md	Project	Committed	Main project context
.claude/skills/	Project	Committed	Project Agent Skills
.claude/commands/	Project	Committed	Project slash commands
.claude/agents/	Project	Committed	Project subagents

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3. CLAUDE.md Setup for iOS Projects

The CLAUDE.md file is your primary context provider. Claude automatically loads it at session start.

Root CLAUDE.md Template for iOS

Create CLAUDE.md in your project root:

# Project: [Your App Name]

## Quick Reference
- **Platform**: iOS 17+ / macOS 14+
- **Language**: Swift 6.0
- **UI Framework**: SwiftUI
- **Architecture**: MVVM with @Observable
- **Minimum Deployment**: iOS 17.0
- **Package Manager**: Swift Package Manager

## XcodeBuildMCP Integration
**IMPORTANT**: This project uses XcodeBuildMCP for all Xcode operations.
- Build: `mcp__xcodebuildmcp__build_sim_name_proj`
- Test: `mcp__xcodebuildmcp__test_sim_name_proj`
- Clean: `mcp__xcodebuildmcp__clean`

## Project Structure

MyApp/ ├── App/ # App entry point, App delegate ├── Features/ # Feature modules │ ├── [FeatureName]/ │ │ ├── Views/ # SwiftUI views │ │ ├── ViewModels/ # @Observable classes │ │ └── Models/ # Data models ├── Core/ # Shared utilities │ ├── Extensions/ │ ├── Services/ │ └── Networking/ ├── Resources/ # Assets, Localizations └── Tests/

## Coding Standards

### Swift Style
- Use Swift 6 strict concurrency
- Prefer `@Observable` over `ObservableObject`
- Use `async/await` for all async operations
- Follow Apple's Swift API Design Guidelines
- Use `guard` for early exits
- Prefer value types (structs) over reference types (classes)

### SwiftUI Patterns
- Extract views when they exceed 100 lines
- Use `@State` for local view state only
- Use `@Environment` for dependency injection
- Prefer `NavigationStack` over deprecated `NavigationView`
- Use `@Bindable` for bindings to @Observable objects

### Navigation Pattern
```swift
// Use NavigationStack with type-safe routing
enum Route: Hashable {
    case detail(Item)
    case settings
}

NavigationStack(path: $router.path) {
    ContentView()
        .navigationDestination(for: Route.self) { route in
            // Handle routing
        }
}

Error Handling

// Always use typed errors
enum AppError: LocalizedError {
    case networkError(underlying: Error)
    case validationError(message: String)