Give your simulator superpowers

RocketSim: An Essential Developer Tool
as recommended by Apple

Issue 48
Jul 12, 2025

Finding hidden features in new Xcode releases is always fun. Right after a release you can open up Twitter and find tweets like the one from Andy Aude.

This week's beta release of Xcode felt different for me though: RocketSim had a little sherlock. I have to admit: I felt bad the first time I read it. I can't imagine how it must feel to be Sherlocked by Apple if it's your full-time business!

RocketSim is just a hobby so it doesn't hurt me too much. The challenge with these kinds of situations is to get energy out of it and transform it into motivation to step up your game. Competition is nothing new, in fact, there were already more tools available that allow you to enhance the simulator. It's actually a competition that makes us level up and get the best out of our creativity.

The recording option in Xcode won't stop me from developing RocketSim as it's mainly a fun project for me to work on. I'm pretty sure it's still adding value and I'll promise you to deliver even more value soon.

Want to stay up to date? Make sure to give my RocketSim Twitter account a follow.

Enjoy this week's SwiftLee Weekly!

THIS WEEK'S BLOG POST
Xcode 12.5 dropped a bunch of new features. One of them allows us to mark assertions as expected to fail which at first might seem redundant: why not use XCTSkip? Or just disable the test completely? There are enough reasons why this new feature is a very welcome addition to the XCTest framework.

SPONSORED
XCOrganizer is a tool that lets you easily locate any project on a disk. Browse through Xcode Projects, Xcode Workspaces, Swift Playgrounds, and Swift Packages grouped by types. Assign tags based on project goals. Add whatever you’re working on to favorites. Humans can’t possibly keep track of all project names. XCOrganizer can.

SWIFTLEE FEATURES
One of my main projects over the past few months has been improving the quality of my newsletter. This week I finished that effort by integrating SwiftLee Weekly into my blog.

You can now find the latest issues right in your browser and reference back to earlier editions.

TWEET OF THE WEEK

The UIAppearance API and SwiftUI aren’t always friends but can become useful by using this tip from Conrad Stoll. I found it really cleaver to think about using a UIHostingController in that way.

NEW SUPPORTER
I feel honored to announce I've got sponsored by Sindre for 1 (!!) year! Make sure to follow him if you didn't yet as he delivers a ton of value with his open-source work in the community.

CURATED FROM THE COMMUNITY

CODE
I’ve been using Diffable Data Sources a lot lately and enjoyed reading this article by Lee Kah Seng showing some useful insights. For example, I didn’t know about the visual description!
It doesn’t surprise me to see Paul Hudson dropping this blog post one day after the release of Xcode. He does a great job explaining the new features that come with Swift 5.4, packaged in this Xcode release.
NSDataDetector is one of those classes you need to know that exists as you might need it one day to prevent yourself from writing complicated logic. Thanks to Filip Němeček I’m aware of this again.
Network Inspectors are not new, in fact, we have quite a lot already. However, Alex Grebenyuk elaborates what makes Pulse different: no certificates, just a simple package to add to your app.

VIDEO
I really liked this episode by Vincent Pradeilles in which Krzysztof Zabłocki demonstrates how Sourcery works for code generation. If you don’t use Sourcery yet this is worth a view!
Many posts and videos cover how to build apps but how do we actually deliver those apps to our users? Sean Allen got us covered with this video going from beginning to end.

OPTIMIZATION
Sindre Sorhus (yes, the same one that sponsored me) works full-time on open-source projects and I bet you all have used some work from him someday. I’m using his work a lot and found this contributing document worth a share as it emphasizes that contributing should be fun and doesn’t need big code changes. Check it out if you’re struggling to find a way to contribute to open-source projects.

NEWS
The winners of the Swift Community Awards are announced. Congrats to all the winners! Make sure to check out all nominations too as there are a ton of valuable resources to find for you as a developer.

THANK YOU
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