A combination of three open-source skill packs, from Appllama, Expo and designer Emil Kowalski, is being shared online as a way to “reverse engineer any iOS app” with an AI agent. The pitch overstates it: none of them decompiles apps or analyzes binaries. What they do is teach agents such as Claude Code, Codex or Cursor to study the design of successful apps and rebuild similar screens with Expo and React Native.

AI skills for recreating iOS app design in 20 seconds

Appllama studies screens from top-grossing apps and sets a quality bar for building new ones.
Expo publishes official skills for building, shipping and debugging Expo apps.
Emil Kowalski adds skills for animation, interface design and Swift.
All three are MIT-licensed, but Appllama’s MCP and some Expo services are paid.

The wording matters. In security work, reverse engineering an iOS app means decrypting and disassembling its binary with specialized tools, and these packs do nothing of the sort. Here the term is used in a product sense: looking at how the best apps handle navigation, paywalls or onboarding, and carrying those patterns into your own app. Designers have done this for years; these skills automate it for agents.

Appllama: studying the top-grossing apps

Appllama describes itself as a design library of the highest-grossing mobile apps, with their real screens, flows and UI patterns plus revenue and download context. Its repository ships two skills. appllama-usage teaches the agent to use the Appllama MCP server to research app categories, and appllama-app-design-skill sets the bar for building screens with Expo and React Native: Apple Human Interface Guidelines fidelity, semantic colors, native controls, correct navigation and animations kept off the JavaScript thread.

The design skill works without the MCP, but the research skill needs it, and MCP access is part of Appllama’s paid Pro plan, with credits that reset each month. Installation uses the skills CLI:

npx skills@latest add appllama/appllama-skillsCode language: CSS (css)

Expo and Emil Kowalski: building and polishing

Expo’s official skills cover the full lifecycle of an Expo app: project structure, Expo Router, Reanimated animations, native components, Swift and Kotlin modules, SDK upgrades and migrating web apps to native. Expo separates the free skills from those that depend on its paid EAS services, such as cloud builds, store submission and over-the-air updates. In Claude Code they install as a plugin from the official marketplace.

claude plugin install expo@claude-plugins-officialCode language: CSS (css)

Emil Kowalski’s skills come from a designer and engineer who has worked at Vercel and Linear, and they focus on what he calls taste: picking the right animation curve, reviewing and improving animations, applying Apple’s design principles, writing modern Swift and stress-testing a UI with worst-case data. Kowalski argues that agents lack good judgment on their own and that his skills list the small mistakes they make and how to fix them.

What it adds and where to be careful

For teams building with Expo, the combination makes sense: a source of design references, the framework’s official rules and a layer of judgment on animation and interface. All three repositories are MIT-licensed, install into Claude Code, Codex, Cursor and other skills-compatible agents, and can be used separately.

The risk is taking the idea of copying apps literally. Borrowing navigation or onboarding patterns is common practice, but reproducing another app’s interface, branding or artwork can run into intellectual property problems and App Store review rules against copycat apps. And as with any skill pulled from the internet, it is worth reading its contents before giving an agent access to a project.

Frequently asked questions

Do these skills reverse engineer iOS apps?

Not in the technical sense. They do not decompile or analyze binaries; they study the visible design of successful apps and help build similar screens with Expo and React Native.