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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

Comments (31)

saaaaaam · 4m ago

Doesn’t work at all for me.

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.

WhitneyLand · 9m ago

Hey Kyle, looks very cool!

- 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.

kylemacomber · 3h ago

On a personal note, I wanted to thank the HN community. I’ve been reading HN since college (for over 15 years now!) and it’s been formative in my development as a software engineer and leader.

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.

FlamingMoe · 1h ago

Neat. I just tried it out and one thing I was pleasantly surprised about was the styling it came up with. It was sleek, and it did not have the purply gradienty tailwindy styling that I always get from Claude. Did you do much to adjust the prompt for custom styles?

kylemacomber · 1h ago

Styling apps is an area we're excited to spend time exploring. Today in our system prompt we say "ALWAYS make the design Apple-like. Use clean typography and consistent padding/spacing." However, tbh it's not something we carefully tested.

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.

sukh · 23m ago

I’ve been playing with the TestFlight build and it’s really solid. Can you share any under the hood details of how the system is able to accurately map the loose prompt to fully native SwiftUI components. Mostly curious because I’d love to also build internal data dense apps typically better suited for desktop.

Great work and I hope to become a paying customer soon!

jacobx · 3m ago

Yeah, the prompt is just asking Claude to generate a SwiftUI iPhone app. The recent models have been able to generate really good Swift code, so we just have a set of best practice instructions we've been accumulating (telling it to make an app with @main, pointing it to/away from some APIs, encouraging it to persist things in UserDefaults, etc).

I think most of that would work pretty well for making SwiftUI desktop apps too.

avarun · 1h ago

Seems like a cool concept! I downloaded and entered an email address but haven't received a verification code yet after 10 minutes. It's an Apple Private Relay email if that matters.

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.

jacobx · 1h ago

That's weird, can you try hitting back and then the forward arrow again? That should resend the email. If that still doesn't work, let me know and we can investigate on the backend.

We've definitely been hearing from users who don't like OTP, we'll try to get additional login options added soon.

sunnybeetroot · 52m ago

That’s interesting, on a desktop device I would agree. However having to create an account on 1Password for an app I just want to try is a pain compared to using Apple’s Hide my email and entering in the OTP. I get that it didn’t work for you but it did for me.

HellsMaddy · 1h ago

Very cool! Was it difficult to get Bitrig approved on the App Store? If I had to guess just based on the idea, it seems like the sort of thing Apple would take issue with.

kylemacomber · 1h ago

Heh... it definitely wasn't an overnight approval. However, Apple has relaxed the guidelines for developer tools compared to the early days of the App Store. If you look today there are Python IDEs, Jupyter Notebooks, and various other apps that execute user generated code. The key guideline to be mindful of is 2.5.2.

pybae · 12m ago

this is super super cool - awesome to see something technically hard and novel. congrats on the launch!

Erazal · 1h ago

I’ve just tested it out, and purchased a subscription within 5 minutes, for an app we were seriously discussing with a friend over the last days.

Keep crushing!

tdonnelly · 49m ago

Great, excited to see what you build with the bitrig. Definitely reach out with any questions or features you’d like to see!

Erazal · 50m ago

Quick note: it’s hard to pull down the prompt panel down, and makes for a frustrating UX (just there)

tdonnelly · 48m ago

Thanks for the feedback - that one has come up before so stay tuned for updates.

fragmede · 12m ago

I'm on an iPhone SE, and the UI doesn't quite fit. The response text isn't easily scrollable, so I have to drag the text up, instead of just scrolling.

kylemacomber · 7m ago

Thanks for the heads up. I confess, I did not test it on an SE. We'll take a look!

saadn92 · 1h ago

This is a really good idea, but I’ve noticed that, even with developer experience and using Claude code, building a complex app is extremely difficult and takes dozens of prompts to get things actually working. This is probably a great prototyping tool, but I’m curious to know how far this can go to build production level apps.

jacobx · 1h ago

With what we've tried so far, Bitrig already works well for prototyping and making smaller apps.

Really large and complex apps will probably require improvements to both Bitrig and the underlying models. However, both those are coming :)

Johnny_Bonk · 1h ago

So I have an existing typescript project, can I still use your software to build the app part of it in a monorepo?

jacobx · 1h ago

We don't currently have support for editing code directly within a repository, but that's something we're excited about adding.

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.

ForceBru · 1h ago

Are there iOS apps that let me create native Swift apps for my phone (including execution on my device, not in the cloud), on my phone, but _without_ chatting to AI? Just by writing code, the "old" way?

CharlesW · 1h ago

There's the excellent Swift Playground for iOS, requires an iPad: https://developer.apple.com/swift-playground/

kylemacomber · 1h ago

You can edit the code directly in Bitrig, but we haven't optimized the experience around that.

Are you imagining you'd be editing the code with the software keyboard or a paired hardware keyboard?

ForceBru · 1h ago

I'm imagining quick prototyping (including on-device, offline execution) of small pieces of code (potentially growing into a small app) with the software keyboard, like in Pythonista or Pyto.

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.

kylemacomber · 1h ago

Cool, that's really helpful context. We'll take a look at the code editing experience in those apps for inspiration.

sidchilling · 40m ago

I downloaded the app but it keeps crashing on open

jacobx · 37m ago

Sorry to hear that! What version of iOS are you running?

ChrisArchitect · 45m ago

Not to be confused with Bitwig music production studio/software.