Vibecoding a Swift Desktop App - Claude Token Cat

I built a desktop application named Claude Token Cat
- A macOS menu bar app that visualizes your Claude usage with an animated pixel art cat

This was my first vibecoding experience with Claude Code #

Without understanding the language (Swift) or framework (SwiftUI), I relied heavily on AI prompting.

Even when features worked correctly, it was hard to immediately trust AI-generated code #

• Every few commits, I asked whether there were any memory leaks, inefficient logic, dead code, or missed edge cases. I also codified this as a self-review checklist in the project's CLAUDE.md so the AI would perform these checks automatically before presenting code changes.

  • There were no critical issues, but these prompts led to meaningful improvements. For example, it caught a retain cycle in TokenUsageManager's Task blocks where [weak self] was missing, and fixed an edge case where CancellationError wasn't handled separately, causing a brief error flash in the UI. (511849c)

• I did use AI to improve AI-generated code, but I still wonder how to fully verify AI-generated code. Then again, even human-written code is never 100% perfect. Maybe I'm chasing an unrealistic ideal. I'll just need to respond quickly when bugs are found later.

  • After fix commits, I recorded the lessons in memory or CLAUDE.md to avoid repeating similar mistakes.

• Occasionally, when I spotted questionable logic, I asked the AI why it wrote it that way and requested improvements. (Also updated memory and CLAUDE.md to prevent similar future mistakes)

 private static func formatSubscriptionType(_ type: String?) -> String? {
-        guard let type = type else { return nil }
-        // e.g. "claude_pro" -> "Pro", "claude_max" -> "Max"
-        if let last = type.split(separator: "_").last {
-            return last.prefix(1).uppercased() + last.dropFirst()
-        }
-        return type
+        switch type {
+        case "claude_pro": return "Pro"
+        case "claude_max": return "Max"
+        default: return nil
+        }
     }

The app features came together within 3 days, but the pixel art took much longer #

Whether due to my lack of prompting skill, the AI-generated pixel art just wasn't good enough. I could intuitively tell the cat animations looked unnatural, but I couldn't pinpoint exactly why, unlike a UI bug, which I can describe explicitly.

After several rounds of back-and-forth, I ended up creating all the pixel art from scratch myself in Piskel. (It took a long time to create natural movements because I didn't fully understand how cats move. The pixel art still isn't perfectly natural even now...)
The only thing AI handled was converting .piskel files to Swift code via a Python function.

Easily installable via Homebrew 😺

brew install --cask lylaminju/tap/claude-token-cat