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Stop squashing your commits. You're squashing your AI too
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
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.
Submitted request for WebKit to be added.
In the app I asked it to make, I requested that it use a web view to log into YouTube. The generated app opens a mostly blank screen with no web view, and from what your app told me I think it’s because it’s missing WebKit.
WebKit as a whole might be big, but maybe some subset of it to support web views and get cookies from the web view could be supported?
I'll likely subscribe to your service.
For distribution strategy you could experiment with letting people create simple apps for free and put a perpetual ad for your service ad the bottom of the app.
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.
Really cool product, as someone currently attempting to build a somewhat similar internal tool I have an understanding of some of the pain points involved.
Please don't allow yourselves to be bought out by Apple in the way Buddy Build were back in 2018 though! (and then shut down)
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!
Our background is more in making developer tools, so bitrig was the first product we were excited about, but I think there's a lot of overlap with dynamic UI generation, and we'd love to explore that too.
Could you send us feedback from your project? (Go to the ... menu, then Send Feedback.) If you're not able to use the UI from within your project you can long-press on it from the main screen and choose Recovery Mode, and then enter the project with the interpreter disabled.
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
There's a lot of inspiration we could (and probably will) draw from other products (e.g. Cline's Plan vs Act modes) to build what you're describing.
It can also be really fun and productive to just rapidly iterate on what the AI gives back, without having to take the time to describe it all up front. Sometimes this approach can lead to a new directions you might not have thought of.
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.
Now that I’ve gotten to play around with the app I have to say I’m impressed with how smooth it feels and how well the Swift interpreter works (at least on the basic prompts I’ve tried). One suggestion: allow toggling between an “edit” mode and a “view” mode. The latter would full screen the app and hide the interface for follow up prompts, etc. that would make it easier to approximate how the app will behave in the wild.
I could see this eventually turning into sort of a social platform for mini-apps, by the way! Where users don’t even necessarily need to publish to the App Store if they’re just creating something for themselves and a few friends.
I really like the idea of a platform for people sharing mini-apps! It would be great if people could make lightweight specialized apps for different niches and share them with less friction.
Versus for email OTP you have to switch to your email client, find the email, perhaps refresh a few times waiting for it to come in, click into the email once you see it, highlight the OTP, click copy, then switch back to the app and finally paste. I don’t understand how anybody could possibly prefer it.
- 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.
Keep crushing!
At the moment the prompt just loops for a second and then produces no answer :(
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.
Seems like a reasonable poll question: Which is harder: web app development or native app development?
I was telling a younger colleague the other day how back in the day, I was "competing" with a peer at a company doing nuclear design software (Siemens Power Corp at the time). I was doing it in VisualWorks Smalltalk, he was doing his in straight C and X Windows. Competition aside, both of us built multi window complex graphical design tools that front ended heavy duty simulators, managed various batch jobs, tons of IO, parsing, and lots of color graphic drawing (mine was for fuel assembly (pin and axial enrichments) design, and his was for core layout (where the assemblies go during each reload)). The graphics were simpler (no antialiasing, any alpha we did with clever dithering tricks, not much in the way of animations, though we did each roll some). Both even stored /retrieved into a sort of database (a homegrown data versioning system). But... it was just one of each us for each "app".
Sadly, all Ux development seems orders of more magnitude complicated and beuqacratic now days. Some things are easier and vastly simpler than they used to be, and yet, the sum result is more difficult. I'm not exactly sure why.
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.
(https://bigbangtheory.fandom.com/wiki/Barry_Kripke)
Also, I have been taking the code and advice from Bitrig into Cursor, because it solves problems Cursor struggles with no matter what model it calls.
Your work is empowering, but more than that, it is inspiring, because I can now start to envisage what computer human interaction will look like in the near future.
You have taken away a layer of complexity to creation and that is to be applauded. I think your work is a landmark. I think Bitrig will unleash a new era of creative expression. I wish that I was part of your team.