Give your simulator superpowers

RocketSim: An Essential Developer Tool
as recommended by Apple

A weekly Swift Blog on Xcode and iOS Development

See all

Recent Posts

Simulator Camera: Test your app without a physical device

Camera testing in Xcode's Simulator is possible, but I'm sure you're now wondering: how?! For years, this has not been ...
Read More
  •  3 min read / Xcode

Build performance analysis for speeding up Xcode builds

Build performance can be analyzed in Xcode to speed up your builds. This can quickly speed up your workflow and ...
Read More
  •  9 min read / OptimizationXcode

SwiftUI Architecture: Structure Views for Reusability and Clarity

As your SwiftUI projects grow, the need for a better SwiftUI architecture grows, as it’s easy for view bodies to ...
Read More
  •  4 min read / SwiftUI

YouTube Videos

Tired of waiting for Xcode to finish building? Learn how to analyze and speed up your Xcode builds with real examples and pro tips. In this video, I’ll show you how to analyze Xcode build performance and find the root cause of slow builds — so you can get back to coding faster. You’ll learn: • How to use the Build Navigator and Timing Summary to analyze performance • The difference between clean builds and incremental builds • Common mistakes (like misconfigured run scripts) that slow builds down • The best Xcode build settings for faster iteration • How to spot long compile times with Swift compiler flags • A quick demo showing how to detect slow SwiftUI views • And finally, how RocketSim for Teams helps track build times across your team 🚀 If you shave even 5 seconds per build, you save hours every week. ⸻ Timestamps 0:00 – Spotting signs of slow Xcode builds 0:27 – Run a clean build and start fresh 1:03 – Analyze your build in the Build Navigator 1:45 – Understanding incremental vs. clean builds 2:24 – Diagnosing slow run script phases 3:45 – Debug vs. release configuration best practices 4:24 – Using “Build with Timing Summary” 5:26 – Key Xcode build settings to verify 6:51 – Detecting slow SwiftUI builds with compiler flags 7:32 – Identifying and fixing slow SwiftUI view bodies 8:44 – Tracking build times with RocketSim for Teams 🚀 ⸻ Resources & Links 🚀 Try RocketSim for Teams (14-day free trial): https://teams.rocketsim.app/signup/trial?utm_source=youtube&utm_medium=video&utm_campaign=xcode_builds 📘 Learn Swift Concurrency: https://www.swiftconcurrencycourse.com/?utm_source=youtube&utm_medium=video&utm_campaign=xcode_builds ⸻ About Me I’m Antoine van der Lee — indie iOS developer, creator of RocketSim, author of SwiftLee.com, and host of the Going Indie podcast. I share insights from over a decade of iOS development, from writing Swift code to building profitable indie apps. ⸻ 👍 If you found this helpful, like the video, subscribe for more Swift and Xcode tips, and leave a comment with your build-time improvements! #swiftdevelopment #iosdevelopment #swiftui #swiftlanguage
Why Your Xcode Builds Are Slow (and How to Speed Them Up)
Your SwiftUI code doesn’t have to turn into a mess as your app grows. In this video, I’ll show you how to apply solid SwiftUI architecture principles to make your views reusable, readable, and scalable — without just “moving code around.” You’ll learn how to refactor large SwiftUI views into smaller, testable components, use modifiers intelligently, and create a structure that’s easy to extend across your entire app. ⸻ 🕒 Timestamps 0:00 – Why SwiftUI architecture matters 0:27 – The problem with large SwiftUI views 1:00 – What most developers do wrong (computed property refactors) 1:40 – Extracting reusable views (ArticleRow example) 2:30 – Using modifiers for reusable view styles 3:20 – Creating custom extensions for common UI patterns 4:00 – Combining modifiers and extensions for clean design 5:30 – How to identify reusable components in your codebase 6:00 – Building your own UI component library 6:10 – Final thoughts on reusability and clarity ⸻ 👋 About Me I’m Antoine van der Lee — creator of SwiftLee, RocketSim, and professional Swift courses like the Swift Concurrency Course at https://www.swiftconcurrencycourse.com/?utm_source=youtube&utm_medium=video&utm_campaign=swiftui_architecture Through my writing, videos, and international conference talks, I help iOS developers master Swift, SwiftUI, and concurrency — so you can ship better apps, faster. Follow me on: YouTube → https://www.youtube.com/@AvanderLee?sub_confirmation=1 LinkedIn → https://www.linkedin.com/in/ajvanderlee Twitter/X → https://twitter.com/twannl ⸻ 🚀 Continue Learning • Read more at SwiftLee → https://www.avanderlee.com/?utm_source=youtube&utm_medium=video&utm_campaign=swiftui_architecture • Get weekly iOS insights → https://www.avanderlee.com/swiftlee-weekly-subscribe/?utm_source=youtube&utm_medium=video&utm_campaign=swiftui_architecture • Try RocketSim for faster iOS development → https://www.rocketsim.app/?utm_source=youtube&utm_medium=video&utm_campaign=swiftui_architecture ⸻ 👍 If you found this video helpful: • Like the video — it helps more iOS developers discover this content • Subscribe for weekly Swift and SwiftUI tips, deep dives, and indie development insights Thank you for watching, and happy coding! 🚀 #swiftdevelopment #iosdevelopment #swiftui #swiftlanguage
SwiftUI Architecture Explained: Build Reusable and Readable Views
Swift 6 migration is coming — don’t get caught by hidden concurrency pitfalls. Learn how to prepare your codebase, handle new Swift feature flags safely, and avoid the 5 most common mistakes developers make when adopting Swift Concurrency. 👉 Get the FREE 5-day Swift Concurrency Playbook: https://www.swiftconcurrencyplaybook.com/?utm_source=youtube&utm_medium=video&utm_campaign=migration_tooling In this video, you’ll discover why Swift’s migration tooling matters, how upcoming Swift 6.2 changes work, and the risks of enabling feature flags manually. Whether you’re upgrading a large project or just starting to adopt Swift Concurrency, these insights will help you migrate confidently — without breaking your app. ⸻ 🕒 Timestamps 0:00 – The importance of Swift migration tooling 0:07 – What are upcoming Swift features? 0:17 – Tracking Swift Evolution proposals 0:32 – Swift 6.2 and approachable concurrency 1:54 – Understanding upcoming feature flags 3:00 – The danger of enabling flags manually 4:16 – Why migration tooling matters 5:10 – What happens when behavior changes 6:00 – Non-isolated, non-sending explained 7:20 – How Xcode helps with migration warnings 8:33 – Automating migrations in large codebases 9:55 – Why manual migration doesn’t scale 10:15 – Key takeaways and next steps ⸻ 👋 About Me I’m Antoine van der Lee, creator of SwiftLee, the Swift Concurrency Playbook (free 5-day course), and a full 65+ lesson professional course at https://www.swiftconcurrencycourse.com?utm_source=youtube&utm_medium=video&utm_campaign=migration_tooling Through my writing, courses, and international conference talks, I’ve helped thousands of iOS developers confidently adopt modern Swift practices and ship better apps. Follow me on: YouTube → https://www.youtube.com/@AvanderLee?sub_confirmation=1 LinkedIn → https://www.linkedin.com/in/ajvanderlee Twitter/X → https://twitter.com/twannl ⸻ 🚀 Continue Your Learning Journey • Start free: https://www.swiftconcurrencyplaybook.com?utm_source=youtube&utm_medium=video&utm_campaign=migration_tooling • Go deeper: https://www.swiftconcurrencycourse.com?utm_source=youtube&utm_medium=video&utm_campaign=migration_tooling • Stay updated: https://www.avanderlee.com/swiftlee-weekly-subscribe/?utm_source=youtube&utm_medium=video&utm_campaign=migration_tooling ⸻ 👍 If you found this video helpful: • Like the video — it helps more iOS developers discover this content • Subscribe for weekly Swift tips, deep dives, and indie development insights Thank you for watching, and happy coding! 🚀 #swiftdevelopment #iosdevelopment #swiftui #swiftlanguage #swiftconcurrency
Swift 6 Migration Tooling Explained: How Upcoming Features Will Change Your Code
Async/await in Swift can be a game-changer — or a nightmare if you fall into these 5 common traps. In this video, I’ll walk you through the top Swift Concurrency mistakes that cause UI freezes, App Store rejections, and months-long migrations — and how to fix them. 👉 Get the FREE 5-day Swift Concurrency Playbook: https://www.swiftconcurrencyplaybook.com/?utm_source=youtube&utm_medium=video&utm_campaign=5_mistakes_async_await This free email course breaks down each mistake in depth and helps you write clean, predictable, and modern concurrent code — even if you’ve been using Swift for years. ⸻ 🕒 Timestamps 0:00 – Intro 0:38 – Mistake 1 1:47 – Mistake 2 2:31 – Mistake 3 3:10 – Mistake 4 3:36 – Mistake 5 4:20 – Summary & How to Learn More ⸻ 👋 About Me I’m Antoine van der Lee, creator of SwiftLee, the Swift Concurrency Playbook (free 5-day course), and a full 65+ lesson professional course at https://www.swiftconcurrencycourse.com?utm_source=youtube&utm_medium=video&utm_campaign=5_mistakes_async_await Through my writing, courses, and international conference talks, I’ve helped thousands of iOS developers confidently adopt modern Swift practices and ship better apps. Follow me on: YouTube → https://www.youtube.com/@AvanderLee?sub_confirmation=1 LinkedIn → https://www.linkedin.com/in/ajvanderlee Twitter/X → https://twitter.com/twannl ⸻ 🚀 Continue Your Learning Journey • Start free: https://www.swiftconcurrencyplaybook.com/?utm_source=youtube&utm_medium=video&utm_campaign=5_mistakes_async_await • Go deeper: https://www.swiftconcurrencycourse.com/?utm_source=youtube&utm_medium=video&utm_campaign=5_mistakes_async_await • Stay updated: https://www.avanderlee.com/swiftlee-weekly-subscribe/?utm_source=youtube&utm_medium=video&utm_campaign=5_mistakes_async_await ⸻ 👍 If this video helped you understand async/await better: • Like the video — it helps more developers discover this content • Subscribe for weekly Swift tips, deep dives, and indie development insights Thank you for watching, and happy coding! 🚀 #swiftdevelopment #iosdevelopment #swiftui #swiftlanguage #swiftconcurrency
5 Async/Await Mistakes Every Swift & iOS Developer Makes (And How to Fix Them)

Don’t miss any future videos — Subscribe to my channel.

The Essential Swift Concurrency Course for a Seamless Swift 6 Migration.

Learn all about Swift Concurrency in my flagship course offering 13 modules, 78 lessons, videos, code examples, and an official certificate of completion.

Updated for Swift 6.2 and now available with a limited-time launch offer.

Go to the course

Swift Keywords

Do you know how to use each keyword in Swift?
Click on the keyword to learn more and explore code examples.

actor associatedtype async @autoclosure available await break catch class continue defer @discardableResult @dynamicCallable @dynamicMemberLookup enum @escaping fileprivate for @globalActor guard infix isolated lazy @MainActor nonisolated optional postfix @propertyWrapper private protocol required @resultBuilder rethrows sendable some struct subscript throw throws try typealias @unchecked @unknown unowned weak where while

Career Advice – Grow your career

Looking to grow your career in iOS development? With years of experience leading teams at WeTransfer and building SwiftLee into a go-to resource for over 140,000 developers monthly, I offer insights on everything from launching successful side projects to scaling app users. Whether you’re refining your Swift skills, building an online presence, or creating passive income with courses, I’m here to help you navigate your journey.

Book a 1:1 with Antoine

Ready to make your side project a success?

Tired of the 9-to-5 grind and endless meetings? Imagine turning your side project into a six-figure income and going fully independent—just like I did. Learn my proven steps to transform your passion into profit.

Start your journey now

The Going Indie Podcast

Discover stories and strategies from creators who’ve turned side projects into thriving businesses. Ready to take the leap?

Listen anywhere
Watch on YouTube

See all

Learn more about Swift

Swift Computed Property: Code Examples

Computed properties are part of a family of property types in Swift. Stored properties are the most common, saving and ...
  •  6 min read / Swift

Property Wrappers in Swift explained with code examples

Property Wrappers in Swift enable you to extract common logic into a separate wrapper object. Introduced at WWDC 2019 and ...
  •  11 min read / Swift

Async await in Swift explained with code examples

Async await is part of the new structured concurrency changes that arrived in Swift 5.5 during WWDC 2021. Concurrency in ...
  •  9 min read / ConcurrencySwift
FREE 5-day email course: The Swift Concurrency Playbook by Antoine van der Lee

FREE 5-Day Email Course: The Swift Concurrency Playbook

A FREE 5-day email course revealing the 5 biggest mistakes iOS developers make with with async/await that lead to App Store rejections And migration projects taking months instead of days (even if you've been writing Swift for years)

Get the Course

See all

Learn SwiftUI

SwiftUI Architecture: Structure Views for Reusability and Clarity

As your SwiftUI projects grow, the need for a better SwiftUI architecture grows, as it’s easy for view bodies to ...
  •  4 min read / SwiftUI

SwiftUI Toggle: A Complete Guide

A SwiftUI Toggle is a common UI element that allows users to switch between states. It often turns a binding ...
  •  3 min read / SwiftUI

@ViewBuilder usage explained with code examples

The @ViewBuilder attribute is one of the few result builders available for you to use in SwiftUI. You typically use ...
  •  4 min read / SwiftUI

Build Apps Faster using RocketSim

Recommend by Apple as an “Essential Tool for Developers”, RocketSim helps thousands of engineers to save hours per week. Discover these articles and learn how you can leverage RocketSim to improve your workflow:

App Actions

App Actions Perform Menu

RocketSim Tools

See all

Combine all the things

Combine and Swift Concurrency: A threading risk

Many developers are migrating from Combine to Swift Concurrency. Swift Concurrency is here to stay, and Combine hasn't received updates ...
  •  5 min read / CombineConcurrency

@Published risks and usage explained with code examples

@Published is one of the property wrappers in SwiftUI that allows us to trigger a view redraw whenever changes occur ...
  •  4 min read / CombineSwiftUI

RunLoop.main vs DispatchQueue.main: The differences explained

RunLoop.main and DispatchQueue.main are often used as schedulers within Combine. During code reviews, I often encounter inconsistency in using one ...
  •  3 min read / Combine

See all

Dive into Core Data

How to observe NSManagedObject changes in Core Data using Combine

Observing changes in Core Data NSManagedObject instances with Combine publishers can be a great solution to keep your user interface ...
  •  3 min read / CombineCore Data

Data validation on insertion, update, and deletion in Core Data

Data validation in apps is important to make sure we save data conforming to the business rules. A name should ...
  •  3 min read / Core Data

Derived Attributes to improve Core Data Fetch Performance

Derived attributes are available since iOS 13 and aim to improve fetch performance in many different scenarios. Although we have ...
  •  3 min read / Core Data

See all

Be an expert on Xcode

Simulator Camera: Test your app without a physical device

Camera testing in Xcode's Simulator is possible, but I'm sure you're now wondering: how?! For years, this has not been ...
  •  3 min read / Xcode

Build performance analysis for speeding up Xcode builds

Build performance can be analyzed in Xcode to speed up your builds. This can quickly speed up your workflow and ...
  •  9 min read / OptimizationXcode

Derived Data: 5 Things iOS Developers Do Wrong

The Derived Data folder is one of the most important directories an iOS developer relies on. While you don't work ...
  •  6 min read / Xcode

See all

Get better at debugging

Introducing Diagnostics: Improved Debugging and User Support

A diagnostics report that helps you solve bugs and improve user support at the same time. I've been writing apps ...
  •  5 min read / DebuggingOptimization

Network Link Conditioner: Simulating Slow Networking

The Network Link Conditioner allows you to test your apps under slow networking conditions on macOS and iOS. The tool ...
  •  4 min read / DebuggingOptimization

Memory consumption when loading UIImage from disk

Memory consumption can quickly increase if you load many images from the disk using UIImage. You'll generally load images from ...
  •  5 min read / DebuggingSwiftUI

See all

Improve your workflow

Testing push notifications on the iOS simulator

Testing push notifications in the iOS simulator makes adding support for remote notifications much more effortless. However, you often must ...
  •  5 min read / Workflow

Designing Apps: 5 Methods to improve your workflow

Designing apps can be challenging if you don't have a design background. Many of you who read my blog are ...
  •  3 min read / Workflow

Test-Driven Development (TDD) for bug fixes in Swift

Test-driven development (TDD) is a technique that requires you first to write a failing test before you start implementing a ...
  •  4 min read / Workflow

See all

Optimize yourself and improve

Build performance analysis for speeding up Xcode builds

Build performance can be analyzed in Xcode to speed up your builds. This can quickly speed up your workflow and ...
  •  9 min read / OptimizationXcode

App Store Optimization: Real-world Best Practices

App Store Optimization is important for every app's success. You've spent a lot of time building a fantastic product, so ...
  •  9 min read / Optimization

Introducing Diagnostics: Improved Debugging and User Support

A diagnostics report that helps you solve bugs and improve user support at the same time. I've been writing apps ...
  •  5 min read / DebuggingOptimization
Explore categories Swift Combine Concurrency SwiftUI Core Data Xcode Debugging Workflow Optimization Swift Charts Swift Testing Latest Video
Tired of waiting for Xcode to finish building? Learn how to analyze and speed up your Xcode builds with real examples and pro tips. In this video, I’ll show you how to analyze Xcode build performance and find the root cause of slow builds — so you can get back to coding faster. You’ll learn: • How to use the Build Navigator and Timing Summary to analyze performance • The difference between clean builds and incremental builds • Common mistakes (like misconfigured run scripts) that slow builds down • The best Xcode build settings for faster iteration • How to spot long compile times with Swift compiler flags • A quick demo showing how to detect slow SwiftUI views • And finally, how RocketSim for Teams helps track build times across your team 🚀 If you shave even 5 seconds per build, you save hours every week. ⸻ Timestamps 0:00 – Spotting signs of slow Xcode builds 0:27 – Run a clean build and start fresh 1:03 – Analyze your build in the Build Navigator 1:45 – Understanding incremental vs. clean builds 2:24 – Diagnosing slow run script phases 3:45 – Debug vs. release configuration best practices 4:24 – Using “Build with Timing Summary” 5:26 – Key Xcode build settings to verify 6:51 – Detecting slow SwiftUI builds with compiler flags 7:32 – Identifying and fixing slow SwiftUI view bodies 8:44 – Tracking build times with RocketSim for Teams 🚀 ⸻ Resources & Links 🚀 Try RocketSim for Teams (14-day free trial): https://teams.rocketsim.app/signup/trial?utm_source=youtube&utm_medium=video&utm_campaign=xcode_builds 📘 Learn Swift Concurrency: https://www.swiftconcurrencycourse.com/?utm_source=youtube&utm_medium=video&utm_campaign=xcode_builds ⸻ About Me I’m Antoine van der Lee — indie iOS developer, creator of RocketSim, author of SwiftLee.com, and host of the Going Indie podcast. I share insights from over a decade of iOS development, from writing Swift code to building profitable indie apps. ⸻ 👍 If you found this helpful, like the video, subscribe for more Swift and Xcode tips, and leave a comment with your build-time improvements! #swiftdevelopment #iosdevelopment #swiftui #swiftlanguage
Why Your Xcode Builds Are Slow (and How to Speed Them Up)
Most Popular Posts
  1. Simulator Camera: Test your app without a physical device

  2. SwiftUI Architecture: Structure Views for Reusability and Clarity

  3. Async await in Swift explained with code examples

  4. Build performance analysis for speeding up Xcode builds

  5. MainActor usage in Swift explained to dispatch to the main thread

SwiftLee Weekly Newsletter