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