Give your simulator superpowers

RocketSim: An Essential Developer Tool
as recommended by Apple

Issue 278
Jul 01, 2025

This week's SwiftLee Weekly covers:

  • The end of Flutter?
  • Losing £25,000
  • Time to drop support for older iOS versions?

Enjoy this week's SwiftLee Weekly!

THIS WEEK'S BLOG POST

Sparkle: Distribution apps in- and out of the Mac App Store

When I say 'Sparkle,' for some, it will immediately ring a bell. It's an open-source framework that's available since 2006 (!!) and the most used framework for macOS updates out of the App Store.

This week's article might be a niche topic, but the process, challenges, and solutions are interesting to learn from for everyone.

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CURATED FROM THE COMMUNITY

A Swift Developer’s Guide to Prompt Engineering with Apple’s Foundation Models

Prompt engineering is a skill to train nowadays, and why not do it while focusing on Apple’s Foundation Model?
natashatherobot.com

Why Liquid Glass Is Making Developers Rethink Flutter

The new design with Liquid Glass is great for native apps, but a real challenge for hybrid platforms like Flutter. In fact, the question is whether they’ll even survive this redesign!
ohmyswift.com

Considerations for New iOS Versions

A new iOS version also means reconsidering supported versions. David Smith works on Widgetsmith and has a large user base. He discusses why dropping, e.g., iOS 14, isn’t a simple decision from a business perspective.
david-smith.org

Understanding and Improving SwiftUI Performance

This article by Airbnb is a must-read. The performance optimizations might be extreme for some simple apps, but the approach and learnings are worth reading!
medium.com

How I lost £25,000 running a successful conference

If you think iOS conference tickets are expensive, think again. We’re incredibly fortunate to have access to amazing conferences at relatively affordable prices. Don’t get me wrong—they still cost money. But this article by Tim Condon gives a background story that might make you realize what it means to organize a conference.
timc.dev

SWIFT EVOLUTION

An overview of last week's Swift Proposal state changes. Check them out when they're in review, as it's your opportunity to influence the direction of Swift's future.

CODE SNIPPET OF THE WEEK

Detect barcodes like QR in Xcode's Simulator

Out of beta and now available for everyone: camera support for Xcode's Simulator.

RocketSim streams your macOS camera into the Simulator and works without having to implement any code. You can write regular AVCaptureSession-related code and test as if it's running on a device ✨

More info about this feature can be found in RocketSim's documentation.

You can find this post on Twitter/X, LinkedIn, or Bluesky.

WHAT I'M WORKING ON

Case studies for Swift Concurrency & Swift 6 migration

It's been a week of fun with camera simulation and Sparkle support. Especially the latter has been challenging (as you can read in this week's article), but it does mean we're now able to offer RocketSim out of the App Store.

You might wonder—are you leaving the Mac App Store?

I'm definitely not! We just found out that many companies don't allow to install apps from the Mac App Store, if only after an exception. To get RocketSim in the hands of larger companies, we had to take this step. This already resulted in continued conversations with teams of 50+ app developers (!!). Feel free to reply to this email if you want to use RocketSim with this new distribution channel.

My second priority is finishing the core of my Swift Concurrency Course. I'm currently writing the final module on migration, but I can't just simply write those lessons. I truly want to eat my own dogfood, so I'm using the contents of the lessons to migrate several open-source projects like Diagnostics. Such migration results in unexpected challenges and real-world examples that I can use to optimize my course.

One of the challenges I faced is writing logs, lock-free, but concurrency safe, into a file. I've encountered interesting resources like NIOFileSystem and this thread on the Swift Forums. It shows that a migration to Swift Concurrency isn't only about rewriting some code—it can also mean going back to the drawing table to optimze and guard performance.

Have a great week!

{% if subscriber.rh_reflink != blank %}EARN ROCKETSIM LIFETIME

Share and Earn RocketSim Lifetime & a 1-on-1 coaching session

Apple has recognized RocketSim as an Essential Developer Tool in the Mac App Store, and now you can get lifetime Pro access by sharing your unique referral link!

How to get started:

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Rewards:

  • Earn your first reward after just 3 sign-ups!
  • Check your progress anytime using your referral dashboard.
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Thank you so much for your support, and until next Tuesday,

Antoine