Engineering Knowledge Handbook

Toolchain baseline

Reviewed October 11, 2026 against Swift 6.4, Xcode 27, and the iOS 27 SDK. The app deployment target is separate from the SDK version: check availability before using APIs that require newer iOS versions. Beta-only APIs should be treated as beta until Apple marks them available in a release.

Visual key

🟪 Swift syntax · 🟦 Types and APIs · 🟩 Correct pattern · 🟥 Bug or invalid code · 🟨 Gotcha / availability · 🧠 Plain-language explanation

Swift examples use swift-tagged code blocks. The generated reader applies Xcode-inspired syntax colors, line numbers, and copy controls to Swift, Kotlin, TypeScript, JavaScript, Python, JSON, YAML, Bash, and SQL examples. The lasting visual-style rules are in AGENTS.md.

For the self-contained offline edition, open Engineering Knowledge Handbook — Offline Edition. The legacy filename is intentionally retained for compatibility. Its dashboard groups the material into real domains, then the left navigator drills into topic groups and lessons. Selecting a topic opens it by itself while preserving every other article in the same file. The sticky breadcrumbs, active section map, previous/next links, and domain overview follow the current location. Search indexes headings and nearby explanation/code, and ⌘K / Ctrl+K opens the command palette.

The offline reader includes interview practice with answers initially concealed, Knowledge Recap, guided role paths, cross-topic links, optional focus and Recap Mode, bookmarks, and manually set study status. Topic, domain, search-result, and learning-path reading estimates are calculated from source content; practice time is shown separately. Estimates are not mastery time. The integrated Claude Architect Foundations center separates dated official facts from independent custom practice, saves results locally, and never predicts an official exam outcome. Recent visits, bookmarks, progress, focus and appearance preferences, and expanded folders are stored locally when the browser permits storage for file:// pages. Export/import makes study status and the latest practice result portable. The offline edition is self-contained, works without a server, and does not execute code examples.

The public website is generated from the same Markdown sources as a static, multi-page site with a homepage, domain pages, and individual lesson URLs. Its canonical public domain is devopedia.dev. Build it with python3 build_public_site.py --base-url https://devopedia.dev, then preview dist/ locally with python3 -m http.server 8000 --directory dist. The generated site includes the offline download at dist/downloads/Swift-iOS-Cheat-Sheets-Xcode.html and an optional My Learning page. Email/password, Google, and Apple sign-in, profile editing, and account recovery use the separate Firebase project devopedia-dev; browser-only study remains available without an account. Support mail to support@devopedia.dev forwards to the project owner's verified inbox through Cloudflare Email Routing. The 70 TL Google Cloud cost guard documents the current no-billing setup and a future emergency-stop function.

Readers with verified accounts can propose new content at /contribute/. Only the designated admin can approve or reject proposals on a separate, unlisted admin page. An approved draft enters the editorial workflow documented in CONTENT-REVIEW.md; the public and offline lessons change only after the Markdown source is edited and rebuilt.

Planned product work

See the repository's ROADMAP.md for completed work and remaining deployment decisions.

Recommended reading order

1. Architecture and SOLID and Modern iOS Codebase Blueprint - dependency direction, composition, feature boundaries, and testing seams
2. Swift Types, Protocols, and Generics and Swift Keywords and Syntax Quick Reference - Swift type system and syntax
3. Modern SwiftUI Engineering Reference and SwiftUI and Combine - state ownership, @Binding, Observation, UIKit-era Combine, and view composition
4. Swift Concurrency 6.4 — Quick Reference and Concurrency and Memory - actors, task lifetime, GCD, Sendable, cancellation, and ARC
5. Networking, Security, and Data - APIs, persistence, authentication, and TLS
6. Mobile Tech Lead and Architecture - architecture patterns, mobile leadership, modularization, and platform strategy
7. Backend Engineering and Distributed Systems - API, database, auth, and reliability fundamentals
8. AI Engineering and Orchestration and AI Security and Agent Governance - production AI, agent design, and security
9. Token Optimization and Context Engineering and AI Coding Tools and MCP - cost-aware context and coding-agent workflows
10. AI Agents, Plugins, and Subagents, AI Model Selection and Benchmark Scores, and Build a Private Local AI Assistant - bounded delegation, dated comparisons, and local privacy design
11. Build an AI Plugin, Define a Code Review Agent, and Connect Jira to AI Workflows Across the SDLC - plugin authoring, review contracts, and Jira Cloud workflow design
12. Architecture Case Studies - six end-to-end system-design examples
13. Claude Certification Preparation — Architect Foundations - verified, dated CCA Foundations facts and independent study routes
14. Interview Paths: Mobile, Backend, and AI Systems, then Interview Paths: Senior, Lead, Staff, and Architect - quick role/difficulty routes to canonical answers
15. Senior iOS Interview Knowledge Recap - short Swift/iOS interview hit points in the Knowledge Recap
16. UIKit and Swift Fundamentals and Swift Code Quizzes: Choose the Valid Line and Find the Bug - UIKit foundations and compiler practice
17. Original Thread Coverage - coverage map for the original conversations

Engineering Reference & Knowledge Recap Index

Five-day review plan

Day 1 - Swift language

• Read the type-system and keyword sheets.
• Explain some vs any, generic parameters, associated types, and type aliases aloud.
• Write a generic function with a protocol constraint and a where clause.

Day 2 - SwiftUI

• Review Observation, @State, @Binding, @Bindable, environment injection, and typed navigation.
• Build a small API-backed list with loading, error, empty, and loaded states.
• Review the legacy ObservableObject / Combine path for apps with older deployment targets.

Day 3 - Architecture and data

• Trace UI -> model -> repository -> API or persistence in the codebase blueprint.
• Explain DTO/domain separation and the reason a dependency is injected.
• Review storage choices, API errors, token handling, and TLS pinning.

Day 4 - Concurrency

• Explain actor isolation, actor reentrancy, Sendable, cancellation, and task lifetime.
• Reproduce a GCD deadlock and explain when structured concurrency is clearer.
• Distinguish Swift 6.2+ isolation settings from the behavior of plain async.

Day 5 - Mock interview

• Answer the questions in the Senior iOS Interview Knowledge Recap (Senior iOS Interview Knowledge Recap) aloud.
• Practice the protocol code-review prompts before revealing their separate answer section.
• Keep initial answers under two minutes.
• Add a concrete project example after the definition.
• State tradeoffs instead of presenting one design as universally correct.

Advanced track — Mobile leadership, backend, and AI

1. Explain one architecture case study from Architecture Case Studies without reading the answer.
2. Practice token budgeting, prompt-injection defense, and model routing using 19 and 20.
3. Answer a Tech Lead, Backend, and AI question from Interview Paths: Mobile, Backend, and AI Systems; use its linked concept source for follow-ups.

Claude Architect Foundations study route

Use the independent 7-, 14-, or 30-day plan in Claude Certification Preparation — Architect Foundations. Recheck the official Anthropic exam guide and certification FAQ before booking because access, pricing, policy, and blueprint can change.

Senior-level answer pattern

For most technical questions, use this order:

1. Give the definition in one sentence.
2. Explain ownership or responsibility.
3. Give a small iOS example.
4. Mention the main failure mode.
5. Describe when you would choose an alternative.

Example:

An actor serializes access to its isolated mutable state. Calls from outside the actor normally cross an isolation boundary and therefore require await. I use actors for shared mutable services such as a token store or cache, but I do not make every model an actor because immutable value types are simpler and cheaper.