This week's SwiftLee Weekly covers:

• Xcode Instruments with AI Agents
• System One models in Swift
• Xcode Preview MCP

Enjoy this week's SwiftLee Weekly!

THIS WEEK'S BLOG POST

​Introducing RocketTrace: Using Xcode Instruments with AI Agents​

After months of building and beta testing, I'm happy to finally release RocketTrace to you all. Xcode Instruments simplified, an agentic way to optimize your app's performance efficiently with much lower token costs.
​avanderlee.com​

SPONSORED

​Run cloud agents with Xcode on real Apple Silicon​

Xcloud gives your cloud agents their own macOS environment, complete with your Xcode version, SDKs, and dependencies. They can edit, build, and test iOS or macOS apps while Xcloud handles the infrastructure. Learn more.

MONTHLY GIVEAWAY

Win a ticket for Do iOS Conference in Amsterdam

This November, Do iOS Conference will take place in Amsterdam from November 10th to 12th. I'll be giving a talk myself among speakers like Peter Friese and Tibor Bödecs who I also often curated in this newsletter.

​Join the giveaway for free or get a ticket and see you there?

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

Adding iPhone Duo support to my Video Compression App

After releasing my Video Compression iOS app last week, I started working on support for iPhone Duo. Just like I can use RocketSim and RocketTrace for my own app now, I’m also able to tune and optimize my SwiftUI Agent Skill.

But I wondered: adding iPhone Duo ánd iPad support, where should I start? Would it be better to make my iPhone resizable first? Or should I add iPad support first, then fine-tune for resizability and iPhone Duo?

I decided to start with iPad support. I used a cheap agent model (Composer 2.5 in Cursor) to walk through all iPad screens using RocketSim’s CLI, and asked it to create a web page with screenshots for each page in dark & light mode, at different text sizes. Each screenshot comes with a text field for feedback and a “copy prompt” to return everything at once to the agent.

Am I going extreme? I don’t know. I do know this has been a quick way for me to get an overview of all the pages in my app while I work on something else in the meantime. Token-wise, it’s also doable, as RocketSim’s CLI is quite efficient. I believe it took about 1.8 million tokens for the complete first setup. After adding iPad support, I’ve also been able to add Duo support more easily.

What’s great about this all is that I can ask the agent for feedback on my SwiftUI Agent Skill. That resulted in several updates over the past weeks, so make sure to run npx skills add https://github.com/avdlee/swiftui-agent-skill --skill swiftui-expert-skill in your terminal, and upgrade your agent’s SwiftUI knowledge to support iPhone Duo.