Sheldon Wang

Sheldon Wang

Seasoned iOS Veteran, Mentor

Sitemap

A list of all the posts and pages found on the site. For you robots out there is an XML version available for digesting as well.

Pages

šŸ’¼ Behavioral Interview Questions

STAR-method responses to common and tough behavioral questions. Organized by company culture (Metaā€™s Move Fast vs Snapā€™s creativity vs Appleā€™s quality) and manager types. Real examples from leading iOS teams at top tech companies.

šŸ“š iOS Foundation Questions

200+ rapid-fire Q&A covering Swift language, UIKit, SwiftUI, memory management, concurrency, networking, and design patterns. Perfect for building a strong foundation before tackling system design rounds.

šŸ—ļø iOS System Design Problems

Real-world iOS architecture problems with Mermaid diagrams, production code, and trade-off discussions. Learn to design Instagram feeds, AI chatbots, video streaming apps, and more. Each problem mirrors actual FAANG interviews.

Posts

iOS Advanced UI Components: Custom Views and Complex Interactions

18 minute read

Published:

Creating sophisticated iOS applications requires building custom UI components that go beyond standard UIKit and SwiftUI controls. This guide explores advanced UI development techniques, custom view creation, complex gesture handling, and performance optimization.

iOS System Design: Building a Real-time Messaging System

17 minute read

Published:

Building a real-time messaging system within an iOS app requires careful consideration of network connectivity, message delivery, offline support, and user experience. This guide explores the architecture and implementation of a robust messaging system.

iOS Advanced Core Data: Complex Relationships and Performance Optimization

14 minute read

Published:

Core Data is a powerful framework for managing persistent data in iOS applications. However, building complex data models with multiple relationships while maintaining performance requires careful design and optimization. This guide explores advanced Core Data techniques, complex relationship management, and performance optimization strategies.

iOS System Design: Building a Complex Photo Editing System

12 minute read

Published:

Designing a complex photo editing system within an iOS app requires careful consideration of performance, memory management, and user experience. This guide explores the architecture and implementation of a professional-grade photo editing system that handles multiple filters, real-time previews, and efficient memory usage.

iOS Advanced Animation Techniques: Custom Transitions and Interactive Animations

11 minute read

Published:

Creating engaging iOS applications requires sophisticated animation techniques that go beyond basic transitions. This guide explores advanced animation patterns, custom transitions, interactive animations, and performance optimization techniques that elevate user experience to the next level.

Architecting SwiftUI Apps with The Composable Architecture (TCA)

2 minute read

Published:

TCA scales SwiftUI apps by making state, actions, effects, and dependencies explicit. This primer shows a productionā€‘grade shape: feature isolation, dependency injection, effect cancellation, testing, and navigation. šŸ§©

iOS Advanced Memory Management: ARC, Weak References, and Memory Leaks

9 minute read

Published:

Memory management is crucial for iOS app performance and stability. While Swiftā€™s Automatic Reference Counting (ARC) handles most memory management automatically, understanding weak references, retain cycles, and memory leaks is essential for building robust applications. This guide explores advanced memory management techniques with real, working code examples.

Mastering Combine in 2025: Production Patterns, Pitfalls, and Testing

3 minute read

Published:

Combine is still a fantastic fit for reactive pipelines in UIKit and SwiftUI. This guide codifies production patterns I use for teams shipping at scaleā€”focusing on backā€‘pressure, cancellation, retries, schedulers, and testability. āš™ļø

gRPC vs GraphQL vs JSON: A Comprehensive Comparison for iOS Development

4 minute read

Published:

In the rapidly evolving landscape of software development, choosing the right data communication protocol can significantly impact application performance, scalability, and developer experience. This comprehensive guide explores three prominent approaches to data exchange: gRPC, GraphQL, and JSON, providing insights into their strengths, weaknesses, and ideal use cases.

Bitrate Adaptation in iOS

3 minute read

Published:

In my previous post, I talked about video encoding and streaming in iOS. This post is a quick guide to implementing adaptive bitrate streaming in iOS.

HTTP Response Codes: Not All Heroes Wear 200 (OK)

3 minute read

Published:

As an iOS engineer, Iā€™ve spent more time wrestling with UI constraints and SwiftUI lifecycles than diving deep into the intricate world of HTTP response codes. But recently, a quirky little encounter with a 304 status code sparked my curiosity ā€“ and now, Iā€™m here to share a quick, hopefully entertaining tour of these network communication cryptograms.

XCTest vs Swift Testing: When Unit Tests Grow Up šŸš€šŸ§Ŗ

2 minute read

Published:

Listen up, fellow code warriors! Remember the days when writing unit tests felt like wrestling an angry octopus? Well, Appleā€™s been working some magic, and the new Swift Testing framework is here to save our sanity (and our carpal tunnels).

Mission Impossible: Monetizing Your GitHub Blog (Without Exposing Your Secrets!) šŸš€

5 minute read

Published:

Hey there, aspiring blog mogul! šŸ‘‹ Ready to turn your GitHub-hosted masterpiece into a money-making machine without accidentally sharing your API keys with the entire internet? Buckle up, because weā€™re about to embark on a top-secret mission that would make Ethan Hunt jealous. šŸ•µļøā€ā™‚ļø

Swift Dependency Injection: Your Code`s Personal Therapist šŸ› ļøšŸ§ 

7 minute read

Published:

Dependency Injection (DI) is like a magical organizational wizard for your app architectureā€”think of it as the Marie Kondo of coding, making sure every dependency ā€œsparks joyā€ and sits exactly where it should! šŸ§™ā€ā™‚ļøāœØ In this post, weā€™ll dive into why DI is the superhero your codebase deserves, explore some cool frameworks, and even build a DIY dependency injection container thatā€™ll make your code sing. šŸš€

iOS Machine Learning: Core ML and Vision Framework Integration

10 minute read

Published:

Machine learning has become an integral part of modern iOS applications. Core ML and Vision frameworks provide powerful tools for integrating AI capabilities into your apps. Letā€™s explore practical implementations with real, working code examples.

iOS Security: Implementing Biometric Authentication and Keychain

9 minute read

Published:

iOS security is crucial for protecting user data and ensuring app integrity. Modern iOS apps need robust authentication mechanisms using biometrics and secure storage with Keychain. Letā€™s implement comprehensive security solutions with real, working code examples.

Swift Concurrency: Mastering async/await and Actors

6 minute read

Published:

Swift concurrency with async/await and actors has revolutionized how we write concurrent code in iOS. This modern approach eliminates callback hell and makes concurrent programming more intuitive. Letā€™s explore practical implementations with real, working code examples.

iOS App Architecture: MVVM with Combine and SwiftUI

15 minute read

Published:

Modern iOS development requires robust, scalable architecture patterns that can handle complex business logic while maintaining clean, testable code. MVVM (Model-View-ViewModel) combined with Combine and SwiftUI provides a powerful foundation for building maintainable iOS applications. In this comprehensive guide, weā€™ll explore advanced MVVM patterns with real, working code examples that demonstrate best practices for iOS app architecture.

iOS Networking with URLSession: Building Robust API Clients

15 minute read

Published:

Modern iOS apps rely heavily on network communication to fetch data, upload content, and interact with backend services. URLSession is Appleā€™s powerful networking framework that provides a robust foundation for building reliable API clients. In this comprehensive guide, weā€™ll explore advanced URLSession techniques with real, working code examples that will help you build scalable, maintainable networking layers for your iOS applications.

WWDC 2024 - Lockscreen More Customizable

less than 1 minute read

Published:

In the WWDC 2024 today, Apple show cased that the lock screen bottom camera and flashlight buttons can be customizable moving on! Make sure to adopt this in your app.

Swift and GO`s defer in GCC and Clang

2 minute read

Published:

In Swift and Go, the defer statement is a powerful feature that allows you to execute code just before the current scope exits. This can be incredibly useful for resource management, ensuring that files are closed, or memory is freed regardless of how the scope is exited (e.g., normal return or error).

iOS Core Data Optimization: Building Scalable Data-Driven Apps

12 minute read

Published:

Core Data is Appleā€™s powerful framework for managing the model layer objects in your iOS applications. However, as your app grows and data complexity increases, Core Data performance can become a bottleneck. In this comprehensive guide, weā€™ll explore advanced Core Data optimization techniques with real, working code examples that will help you build scalable, high-performance data-driven iOS apps.

Top 10 Swift 5.7 Syntax Sugar

3 minute read

Published:

Swift has continually evolved to make code more concise and readable without compromising performance. The latest Swift version 5.7 introduces several syntactic sugar features that make coding in Swift even more delightful. Here are the top 10 syntax sugar features with examples:

SwiftUI Performance Optimization: Building Lightning-Fast Apps

7 minute read

Published:

SwiftUI has revolutionized iOS development with its declarative syntax and powerful features. However, as apps grow in complexity, performance can become a critical concern. In this comprehensive guide, weā€™ll explore advanced SwiftUI performance optimization techniques with real, working code examples that you can implement in your projects today.

Top 5 Objective-C Language Performance Drawbacks

3 minute read

Published:

Objective-C, a primary language for iOS and macOS development, offers a robust set of features and a rich ecosystem. However, as with any programming language, it has its performance drawbacks. In this blog, weā€™ll explore the top five performance-related limitations of Objective-C that developers should be aware of.