Launch HN: Bitrig (YC S25) – Build Swift apps on your iPhone

Hacker News Discussion ↗

Overall reception and use cases

  • Many commenters find Bitrig novel and technically impressive, especially the on-device Swift interpreter and “vibe coding on your phone.”
  • Several users quickly subscribed and reported building multiple small apps or proofs-of-concept within hours.
  • Others see it mainly as a prototyping tool; they doubt current LLMs can reliably build complex, production-grade apps without substantial manual work.
  • Some frame it as what Siri/Apple Intelligence could or should become, or as a long-imagined “mobile app to build mobile apps.”

Capabilities, architecture, and missing pieces

  • Bitrig uses Claude to generate SwiftUI, guided by a system prompt emphasizing “Apple-like” design and best-practice patterns (e.g., @main, UserDefaults, steering away from certain APIs).
  • The interpreter runs a subset of Swift and calls into real iOS frameworks (SwiftUI, Foundation, MapKit, etc.), not reimplemented ones; async/await is currently discouraged.
  • Users can export a single Swift file for Xcode, and pay to get TestFlight builds; repo-based workflows and a Mac app are planned.
  • Requests include WebKit support, camera permission handling, better API-key flows, more modular code, BYO-LLM keys, server-driven UI, and the ability to embed Bitrig into existing apps.
  • There is interest in a mini-app sharing platform and in extending the approach to macOS and possibly Android in the future.

UX, auth, and pricing

  • Email OTP / magic-link login is contentious: some find it cumbersome versus passkeys or password managers; others like it with Hide My Email. Suggestions include Sign in with Apple and additional options.
  • Users want clearer modes (edit vs view), easier gesture handling, better small-screen layout, and an in-app indicator of remaining messages.
  • $20/month with a nominal 100-message cap feels tight to some given iterative prompting; the team admits the cap isn’t currently enforced and plans to refine tiers.

Stability, bugs, and data concerns

  • Multiple reports of crashes, frozen projects (e.g., canvas-like apps), disappearing chats when backgrounded, missing scrollability on smaller devices, and site issues on non-Safari browsers.
  • Commenters are wary of data collection and secret leakage; the team says projects are stored server-side, not sold or used for training, and all AI calls go through Claude, but some remain cautious.