sujee

For my app which is a AI chat app, I needed to load and show a large number of chat items in a list, SwiftUI is really bad at this. Another issue is, most of Swift markdown libraries don't perform perform well because each elements are rendered as SwiftUI views which introduced a lot of issues So I built my own renderer using TextKit. Even basic things like Settings window is broken. But I still prefer using SwiftUI as It gets the work done faster and I can always fallback to AppKit.

I find that web tech like React are worst than SwiftUI. React also has re-rendering and state management issues

I'm currently building a macOS AI chat app. Generally SwiftUI/AppKit is far better than Web but it performs bad in few areas. One of them is Markdown viewer. Swift Markdown libraries are slow and lacks some features like Mermaid diagrams. To work around this, some of my competitors use Tauri/Electron and few others use WKWebView inside Swift app.

Initially I tried WKWebView. Performance was fine and the bridge between JS and Swift was not that hard to implement but I started seeing few problems especially due to the fact that WebView runs as separate process and usually a single WebView instance is reused across views.

After few attempts to fix them, I gave up the idea and tempted to go fully with Web rendering with Tauri but as a mac developer I couldn't think about building this app in React. So I started building my own Markdown library. After a month of work, I now have a high-performance Markdown library built with Rust and TextKit. It supports streaming and Markdown extensions like Mermaid.

Most of the code was written by Claude Opus, and some tricky parts were solved by Codex. The important lesson I learned is that I’m no longer going to accept limitations in tech and stop there. If something isn’t available in Swift but is available in JS, I’m going to port it. It’s surprisingly doable with Claude.