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Give your simulator superpowers

RocketSim: An Essential Developer Tool
as recommended by Apple

Issue 341
Sep 15, 2026

This week's SwiftLee Weekly covers:

  • Xcode Instruments integrated into Xcode's Simulator
  • A SwiftUI Agent Skill for iPhone Duo, SDK 27 APIs
  • Videos, articles, and meetings for iPhone Duo support

Enjoy this week's SwiftLee Weekly!

THIS WEEK'S BLOG POST

SwiftUI Agent Skill: Install and use with AI coding tools

Xcode 27, iPhone Duo, Resizable iPhone apps, and many new SwiftUI APIs and deprecations. It's time for version 5.0 of my SwiftUI Agent Skill.
avanderlee.com

SPONSORED

Fastlane alternative - Codemagic CLI tools

Are you tired of Ruby and Fastlane installation issues? There's got to be a better way! Discover Codemagic open source CLI tools. It is not a drop-in replacement for all of what Fastlane does (screenshots for example), but we use it at Codemagic to build and publish iOS and Android apps, also versioning and device provisioning. View on GitHub.

Monthly giveaway

Win a ticket for Swiftsonic '26

Win a ticket for Swiftsonic '26, a conference taking place in from November 20-22, Nashville, Tennessee, US. With Betsy Langowski (former Apple SwiftUI evangelist with 15 years in Cupertino), and other headline speakers like Klemens Strasser, Ellen Shapiro, and many more, a conference you don't want to miss!

CURATED FROM THE COMMUNITY

Meet with Apple - iPhone Duo Grouplabs

iPhone Duo is here, which also means a new device to support with your apps. Make sure to Meet with Apple online and get your apps ready.
developer.apple.com

Apple Developer Videos for iPhone Duo

iPhone Duo Apple Developer videos are now available, covering design, adaptive layouts, and more.
developer.apple.com

We built an app inside Instagram, then sold it

From building an app to selling it: I always wonder how one would feel after selling a product you actually love or enjoyed building. This is a great story about the journey of selling Mindie.
sage.me

Adapting your app for iPhone Duo

If you don't like watching the developer videos on iPhone Duo, you might enjoy reading this article series by Sarunwinstead.
sarunw.com

iOS Simulator Browser Preview for Codex, Claude, and Cursor

Stream Xcode's Simulator directly into Codex, Claude, and Cursor. Select any accessibility element and prompt your feedback for a faster loop and communication with your agents. Now available!
rocketsim.app

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.

WHAT I'M WORKING ON

Connecting the dots: RocketTrace integration for RocketSim

While I'm getting closer to the release date of RocketTrace, allowing you all to benefit from easier Xcode Instruments result parsing, I'm also preparing for a world with two developer tools running at the same time.

The original idea behind RocketTrace started within RocketSim. I tried to create a "Start performance trace" button in the side window, so you could quickly spin up Instruments to validate the performance of your running Simulator app.

Unfortunately, I quickly hit a wall of limitations, but I also realized I was basically creating a whole new app. Focus is key, so I decided to develop it as a separate app.

With both apps in a mature state, I've now been able to connect the dots and finally deliver what I was dreaming of before:

Using your recent builds for the Simulator, a performance trace recording is just one click away. After the recording completes, RocketTrace will open with insights on SwiftUI, Swift Concurrency, Hangs, Hitches, and more.

Anyone on the beta of RocketTrace will automatically have access to this as soon as the next version of RocketSim lands. Join the waitlist here.

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{% if referral_count >= 30 %}You’re one of SwiftLee Weekly’s top advocates

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{% assign referrals_needed = 30 | minus: referral_count %}Refer {{ referrals_needed }} more to unlock RocketSim Pro Lifetime.

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You’ve referred {{ referral_count }} developers. {% assign referrals_needed = 10 | minus: referral_count %}Refer {{ referrals_needed }} more to unlock Swift Concurrency Course access.

{% elsif referral_count == 2 %}One more referral unlocks your first reward

You’ve referred two developers. One more unlocks 50% off RocketSim Pro Yearly.

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{% if referral_count < 30 %}Rewards:

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Antoine