Launch HN: Bitrig (YC S25) – Build Swift apps on your iPhone
Bitrig lets you create native Swift apps for your phone, on your phone, just by chatting with AI. It’s like Lovable for iPhone apps.
Here's a video of Bitrig in action: https://youtu.be/CUlWhF3ERME
We created SwiftUI at Apple to help developers make better apps with less code. Bitrig lets anyone build at this level of polish. If you've thought about making an iPhone app, Bitrig is the easiest possible way to get started with Swift.
Bitrig uses Claude Sonnet 4.0 with a simple system prompt and tool definitions to generate native Swift code. Normally running this on an iPhone would require compiling and signing it with Xcode, and you can’t run Xcode on an iPhone. So we did something… creative. We wrote a custom Swift interpreter! Among other things this lets you instantly preview your app in Bitrig and share it with just a URL.
If you have a paid Apple developer account, you can connect it with Bitrig. We’ll compile your app on our server and upload it to App Store Connect, so you can distribute it on TestFlight or the App Store. This last step also gives you a fully optimized build of your app that you can install right on your Home Screen.
We think there’s something electric about building apps directly on your phone. We hope you give Bitrig a try!
We’re ingesting Apple’s SDK frameworks into Bitrig piece by piece. If you try to build something and hit a missing framework, let us know and we’ll prioritize adding it.
Download Bitrig on the App Store: https://apps.apple.com/us/app/bitrig/id6747835910
What happens if you go over 100 messages/month?
I just burned my 5 free messages to get a simple toggle button working that just says "win" (with animated fireworks!) and "lose". I'm sure I'm not an efficient prompter, but it seems I'd knock out 100 messages easily in an afternoon, which looks to be the monthly limit at $20/mo.
(This is coming from someone who has no idea how expensive it would be to 'vibe code' using something like Claude ... so it may be an entirely unfair assumption that you could chat with this 'unlimited' for $20/mo ... that's what I have in my head as 'reasonable' only because that's what I pay for Gemini or ChatGPT and, for all intents and purposes, it feels 'unlimited'.)
We're still in the learning phase, and are going to adjust the plans based on exactly the kind of considerations you're raising
I don’t pipe up very often, but I visit HN almost every day. Many of the books I read, blogs I frequent, and podcasts I listen to, I found via HN. I think it’s fair to say, if it weren’t for HN, that Bitrig wouldn’t be Bitrig and SwiftUI wouldn’t be SwiftUI.
Entered my my prompt… It did a bunch of stuff - apparently initially focused on making me an app icon which I don’t really care about.
I moved away from the app, went back and everything had gone and my prompt was just sitting there by itself.
I said “please proceed” and it opened a new chat, did the same thing. It was doing stuff, I moved to something else, went back, everything vanished.
So that’s two of my five free messages zapped. And all of my patience.
Moving in and out of the project while messages are sending is a more fragile area of the app and we have some bugs to fix there.
With your sunscreen example, I should be able to just ask Siri to do exactly this, and it could tap me in my pocket, show me a custom UI to log periodically and then disappear.
Not sure on limitations of APIs on iOS but definitely feels like there is space for a better voice assistant, just like how Raycast have created a better Spotlight on Mac.
Looks very cool so far!
For the most part, I think the look and feel of the apps benefits from SwiftUI baking Apple's design system into the defaults so heavily.
- If Bitrig can do things like let your app have editable data, or make rest api calls, etc. it would be nice to see a little more in the demo video.
- Sounds like you don’t have an expensive mic/studio for recording, but luckily this is free and can work wonders for your audio: https://podcast.adobe.com/en/enhance
Best of luck with the launch.
Thanks for the tip about the mic. Fun fact: it's me in the video, but it's Jacob doing the narration :P
Great work and I hope to become a paying customer soon!
I think most of that would work pretty well for making SwiftUI desktop apps too.
Also, side note: magic link or email-based OTP login is by far my least favorite method of login, especially for a phone app. It's cumbersome, annoying, and completely unnecessary now that passkeys exist. Barring that I'd still rather use email/pw login any day of the week.
We've definitely been hearing from users who don't like OTP, we'll try to get additional login options added soon.
Keep crushing!
Really large and complex apps will probably require improvements to both Bitrig and the underlying models. However, both those are coming :)
In the meantime, one thing that's worked well for us is building a component/screen/etc as a standalone piece in bitrig, and then bringing it into a larger project from your computer later. You can easily export the code you make in bitrig for those kinds of workflows.
Are you imagining you'd be editing the code with the software keyboard or a paired hardware keyboard?
My workflow often goes like this: got an idea, let me quickly test it on the go, like while walking down the street, working on unrelated stuff or just chilling. Open up Pythonista, write some code, run it, tweak it, etc. If a piece of code becomes important enough, I copy it to the computer and continue working on it there.