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.

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

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"

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 |

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)
    
    var errorDescription: String? {
        switch self {
        case .networkError(let error): return error.localizedDescription
        case .validationError(let msg): return msg
        }
    }
}

Testing Requirements

• Unit tests for all ViewModels
• UI tests for critical user flows
• Use Swift Testing framework (@Test, #expect)
• Minimum 80% code coverage for business logic

DO NOT

• Write UITests during scaffolding phase
• Use deprecated APIs (UIKit when SwiftUI suffices)
• Create massive monolithic views
• Use force unwrapping (!) without justification
• Ignore Swift 6 concurrency warnings

Planning Workflow

When starting new features:

1. Read the PRD from docs/PRD.md
2. Create feature spec in docs/specs/[feature-name].md
3. Use ultrathink for architectural decisions
4. Use Plan Mode (Shift+Tab) for implementation strategy
5. Implement incrementally with tests

Memory Imports

@import docs/PRD.md @import docs/ARCHITECTURE.md @import docs/ROADMAP.md

### Nested CLAUDE.md for Feature Directories

Create `.claude/CLAUDE.md` or `Features/[FeatureName]/CLAUDE.md`:

```markdown
# [Feature Name] Module

## Purpose
[Description of what this feature does]

## Architecture
- Uses MVVM with @Observable ViewModels
- Parent stores create child stores for modal presentations

## Navigation Pattern
### Sheet-Based Navigation
**Pattern**: Parent stores create optional child stores for modal presentations
**Rules**:
1. Parent ViewModel holds `@Published var childViewModel: ChildViewModel?`
2. View observes and presents sheet when non-nil
3. Dismissal sets childViewModel to nil

### Example
```swift
@Observable
final class ParentViewModel {
    var detailViewModel: DetailViewModel?
    
    func showDetail(for item: Item) {
        detailViewModel = DetailViewModel(item: item)
    }
}

Testing

Run tests: mcp__xcodebuildmcp__swift_package_test

---

## 4. PRD-Driven Development Workflow

### Directory Structure for PRD Workflow

docs/ ├── PRD.md # Main Product Requirements Document ├── ARCHITECTURE.md # System architecture decisions ├── ROADMAP.md # Development roadmap & priorities ├── specs/ # Feature specifications │ ├── 000-project-setup.md │ ├── 001-authentication.md │ ├── 002-dashboard.md │ └── template.md └── tasks/ # Task breakdowns ├── 000-sample.md └── [feature]-tasks.md

### PRD Template (`docs/PRD.md`)

```markdown
# Product Requirements Document: [App Name]

## Executive Summary
[Brief description of the product and its primary value proposition]

## Problem Statement
[What problem does this solve? Who experiences this problem?]

## Target Users
- **Primary**: [Description]
- **Secondary**: [Description]

## Success Metrics
| Metric | Target | Measurement |
|--------|--------|-------------|
| User Retention | 40% D7 | Analytics |
| App Rating | 4.5+ | App Store |
| Crash-Free Rate | 99.5% | Crashlytics |

## Core Features

### Feature 1: [Name]
**Priority**: P0 (Must Have)
**Description**: [Detailed description]
**User Stories**:
- As a [user type], I want [action] so that [benefit]

**Acceptance Criteria**:
- [ ] Criterion 1
- [ ] Criterion 2

**Technical Requirements**:
- iOS 17+ required
- Offline support needed
- Data persistence via SwiftData

### Feature 2: [Name]
[Continue pattern...]

## Non-Functional Requirements
- **Performance**: App launch < 2s, smooth 60fps scrolling
- **Accessibility**: WCAG 2.1 AA compliance
- **Localization**: English (primary), [other languages]
- **Security**: Keychain for credentials, certificate pinning

## Out of Scope (v1.0)
- [Feature explicitly not included]

## Technical Constraints
- Swift 6.0+ with strict concurrency
- SwiftUI-only (no UIKit unless necessary)
- SwiftData for persistence
- Minimum iOS 17.0

## Timeline
| Phase | Duration | Deliverables |
|-------|----------|--------------|
| Design | 2 weeks | Figma mockups |