Steve Troughton-SmithFeb 5

'Codex in Xcode can probably take an entire ObjC project and convert it to Swift on its own'

Alright, bet.

I handed it the classic SameGame codebase, gave it my coding style markdown file, and said "So this is an old ObjC app for iOS. I would like you to completely convert it 1:1 to modern Swift, with the coding style in mind. Leave no ObjC behind"

No other prompts needed; I needed to update a few legacy things in the xcode project settings (min OS version, Swift version, etc), and got this:

Show threadSteve Troughton-SmithFeb 5
All automatic, not a line of ObjC remains. Deprecated APIs were all modernized. 5,400 lines of ObjC became 2900 lines of Swift 5
Show threadSteve Troughton-SmithFeb 5
I had long since rewritten the app myself in Swift, so this was only a contrived test of Xcode's new agentic programming support. But it did in 5 mins what took me months (years?) of on-again/off-again effort and preparation
Show threadSteve Troughton-Smith
Nonetheless, if this is what you're up against, you have /absolutely no shot/ of convincing a brand new Xcode developer that they should spend weeks doing something the hard way ('because that's how I did it!') when the IDE will do it for you in the background before you've finished your coffee. This feels much more like the shift from assembly code, even punch cards, to programming languages. If you've kept within the Apple bubble up to now, this stuff is going to be a massive shock
Feb 5 at 1:40pmIvory for Mac
Show threadSteve Troughton-SmithFeb 5
Your only reprieve is that this stuff is so expensive right now. Codex at $20/mo is fine for tinkering, but you'd be forced into the $200/mo plan if you used this every day. Claude, which I've never used, also sounds way too expensive for my taste. If (and when) LLM-based agentic programming like this becomes free, gameover
Show threadSteve Troughton-SmithFeb 5

ObjC to Swift is too easy, all things considered. What about porting the app to another platform, like… Android?

Hold my beer

Show threadSteve Troughton-SmithFeb 5

So yeah now I have a 1:1 recreation of classic SameGame in Android's Java/XML 😑

I passed it the Swift version of the project (*that it had created from the original ObjC project*), and instructed it to turn it into an Android project that I could just open in Android Studio and install. Did the lot, made the build config, transcoded the audio to .ogg, and now it just… *exists* on Android.

It preserved my animations, my layout, my navigation, everything. It did require guidance for last mile

Show threadSteve Troughton-SmithFeb 5
It even supports splitscreen 🤣
Show threadSteve Troughton-SmithFeb 5

RIP cross-platform frameworks.

Remember how much effort Microsoft put into acquiring WinObjC and trying to build an SDK with it and convincing developers to use it, and how nobody did?

You could do that.

Or you could ask Claude/Codex to just port an app for you in 15 minutes

Show threadSteve Troughton-SmithFeb 6
I'd tried this conversion process before, perhaps a year ago, with the agent feature in ChatGPT (the one that boots up a cloud VM to perform a task) and got nowhere. There has clearly been a lot of progress made here in a short amount of time, no doubt spurred on by what Anthropic has been doing with Claude. It's hard to believe Xcode has been retooled to support both so fast
Show threadSteve Troughton-SmithFeb 6

Since people have been asking, the initial iOS -> Android porting prompt used here was:

"Hi codex. So this here samegame folder is an iOS project written in Swift. I would really like to convert it 1:1 to Android using the latest APIs, such that I can point Android Studio at this project folder and build and run it. Is this something you can do? I want it to look and feel exactly the same as the iOS app"

It then asked me how it wanted it built, and I said Java/XML.

That got me 80% of the way

Show threadSteve Troughton-SmithFeb 6
(I think people think I have some magic LLM juice I sprinkle into my prompts 😅 I do not. I chat with it like I would someone on iMessage)
Show threadSteve Troughton-SmithFeb 6

I didn't think to check it yesterday, but apparently my SameGame Android port happily runs on Android back to 5.0 Lollipop from 2014 👀

I was expecting to simply throw away this project, now I don't really know what to do with it.

If I had had this superpower 10+ years ago, every single one of my apps would have been on Android and Windows Phone

Show threadSteve Troughton-SmithFeb 6
This seemed so hard to believe that I dug my own Nexus 4 out of storage (running Android 5.1) and tried it myself. Works just fine!
Show threadSteve Troughton-SmithFeb 6
I spent some time cleaning up the project and prepping it for Google Play, testing the gameplay and leveling. It maintained the various language localizations too, which was a nice bonus. I'm too lazy to fill out the app icon / screenshot metadata just yet, but I've tested Google Play distribution internally at least. I'm still reeling from the fact that this is possible, never mind viable
Show threadSteve Troughton-SmithFeb 6
The Google Play publishing console is just wizards all the way down. It's such a mess to navigate
Show threadSteve Troughton-SmithFeb 6
Google Play submission review takes as long as Apple's App Review now. They really have locked down so much of Android over the past decade — it's all much closer to Apple's walled garden
Show threadSteve Troughton-SmithFeb 9

One really odd thing about the Google Play equivalent to TestFlight is that you can't upload the same build to multiple tracks, and you can't move that same build along to production. Almost feels like it defeats the purpose?

(Also its TestFlight review took *3 days*. Remember when you could just ship things on Android? I remember…)

Show threadSteve Troughton-SmithFeb 16

I didn't mention it earlier, but this version of SameGame is also now available on Android. It's not a port of the latest version of the codebase, like Lights Off, as this was a different kind of experiment. But since it was so successful, it opened the door for Lights Off and future, better, more-complex apps on the platform

https://play.google.com/store/apps/details?id=com.highcaffeinecontent.samegame

Show threadSteve TibbettFeb 9
@stroughtonsmith You should be able to promote a build from one track to the next? Is this available?
Show threadFrederik SeiffertFeb 9
@stevex @stroughtonsmith Yes, but that UI element is only available for releases in the internal testing track. But if you remember to go there you can promote to whatever tracks.
Show threadSteve Troughton-SmithFeb 9
@stevex good to know, doesn't help that it's so confusingly laid out
Show threadSteve TibbettFeb 9
@stroughtonsmith Yeah, the whole Google Play experience is a mess. And if something goes wrong, Google support is basically nonexistent. Took me months to get a phone number verified.
Show threadshukuyenFeb 9
@stroughtonsmith review time might be dependent on the account / App. Never seen times longer than a night
Show threadtienshiaoFeb 9
@stroughtonsmith On the screen where you drag-drop/upload your app bundle, there should be a button that says “Add from library” and should allow you to select a previously uploaded version. I’m pretty sure I use that all the time to send the same build to internal testers and external testers. It’s sorta like the TestFlight Builds “library” though the workflow is a little different.
Show threadSam PetherbridgeFeb 8
@stroughtonsmith not for updates. I find they are almost always out in under 2 hours. Usually under 1 hour
Show threadNicolai HenriksenFeb 9

@stroughtonsmith In my experience Google is more strict than Apple in many ways. Google will sometimes do a review of an app out of the blue and possibly “reject” it and give you quite short deadline to fix it.

I am talking about a full review of an existing app, without a new version upload and no activity for months.

Show threadSascha RucksFeb 6
@stroughtonsmith and every 1-2 years it‘s a new „experience“…
Show threadJamie BlumbergFeb 7

@stroughtonsmith I did a small Flutter project at my previous employer, including deploying via App Store Connect and Google Play.

100% agree.

Show threadGKFeb 6
@stroughtonsmith Why don't let the agent fill in the fields?
Show threadSteve Troughton-SmithFeb 6
@gklka I'll leave that to the kool-aid folks
Show threadoisinFeb 6
@stroughtonsmith You single handedly could have saved Windows Phone and I would still be using those lovely designed Nokia phones! 😀
Show threadDaniel BriertonFeb 6
@stroughtonsmith So what I’m hearing is AI could have saved Windows Phone. 😅
Show threadWes MorganFeb 13
@stroughtonsmith Man if someone wanted to launch a new platform right now…
Show threadAndre LouisFeb 6
@stroughtonsmith I do the same thing.
Show threadColinFeb 6
@stroughtonsmith using these tools since July or so has taught me that you definitely don’t have to do that ridiculous prompting format that most AI guys use where you’re like “you are an expert iOS software engineer…”
Show threadAlexander SteinerFeb 6

@stroughtonsmith Inspired by your post, I tried this myself and I can just say wow. From 0 to 1 in just a few minutes. I’m not into Android development at all so this felt just magical.

But I burned through my whole usage limit for the session.

Show threadmirabilosFeb 7
@stroughtonsmith
Show threadGregatron5Feb 5
@stroughtonsmith Nice writeup! I'm curious about code quality. I've been using Claude and it seems to make dumb decisions. They… work… but are suboptimal and often inefficient. (Like introducing unecessary state.) I'm curious if this generated code "good" code or “it works so who cares" code?
Show threadSteve Troughton-SmithFeb 5
@gregatron5 this is one of my oldest projects, dating back to 2008. I wouldn't consider the original code 'good' by any means, so maybe that's an unreasonable comparison. I can't speak for the Android code, but the Swift code I've had it writing has all been very similar to my own
Show threadDaniel LyonsFeb 5

@stroughtonsmith @gregatron5

It seems to be far better at “translating” tasks, like moving from one language or platform to another.

In these tasks it doesn’t have to make so many architectural decisions because you made them already.

Show threadSteve Troughton-SmithFeb 5
@dandylyons @gregatron5 I had it build three new apps yesterday?
Show threadKyle NazarioFeb 5
@stroughtonsmith interesting point! If execution is cheap, then why not do native ports for each platform
Show threadDiego BarrosFeb 5

@stroughtonsmith I wonder how it'd work the other way.

I am working on React Native apps -- yes, I have made some wrong life choices, and it's a corporate decision to "write once, debug everywhere", nonetheless -- and whether it would convert one to native iOS and Android.

But your take is interesting on the whole cross-platform framework scene.

Show threadkhaldoonalnuaimiFeb 6
@stroughtonsmith I said this a couple of months ago, and the RN people didn’t take it well 🫠 If you are a native dev, it is better to learn how to prompt engineer your way to converting your app from SwiftUI to JetPack Compose and vice versa than learn RN and deal with that side of the aisle.
Show threadCodingPanicFeb 5
@stroughtonsmith How is the legibility of both projects? If you wanted to circle back and actually code or fix bugs, is it even possible to do so?
Show threadSteve Troughton-SmithFeb 5
@codingpanic it looks completely reasonable, but I think the honest answer is that you'd ask the AI to do it for you 😅
Show threadJos noemt het gewoon melkFeb 7
@codingpanic @stroughtonsmith The new vendor lock-in
Show threadColinFeb 5
@stroughtonsmith did you do this using Codex?
Show threadSteve Troughton-SmithFeb 5
@hoagie Codex yes, I used the Codex app rather than the Xcode version
Show threadSimFeb 6

@stroughtonsmith this is super interesting, was your prompt very detailed? Or as simple as you suggested

I asked Codex to port my SwiftUI game (Retrogram) to the web thinking it would be straightforward, it ran for an hour and made a huge mess of things. It did not preserve anything of the aesthetic or even the basic functionality

Show threadQuentin ZervaasFeb 6
@simsaens @stroughtonsmith I’m trying convert an objective c codebase to swift with Claude. You really need to hold its hand I’m finding and test extensively. The more detailed the prompt better, and even ask it to build a rosdmap/plan before doing any of it
Show threadRyan PoolosFeb 6
@simsaens this has been my experience with every AI anything. It never works as immediate or easy as the demos. It’s useful but I have yet to see anything as impressive as mastodon posts.
Show threadSteve Troughton-SmithFeb 6
@simsaens it didn't get there with a single prompt, but this is where I started
Show threadOliver DewFeb 6
@stroughtonsmith did Xcode create the Android version? Or some other agentic IDE like codex?
Show threadSteve Troughton-SmithFeb 6
@olsibob I used the Codex app for that
Show threadLen KawellFeb 5
@stroughtonsmith how about converting a SceneKit app to RealityKit?
Show threadFabienFeb 5
@stroughtonsmith And remember these prices are the “cheap so you get hooked" prices not “enough to make a profit and have a sustainable business”. They will only go up as the industry consolidates
Show threadskybrianFeb 5
@fabienmarry @stroughtonsmith I’d take the other side of that bet, assuming we’re comparing equivalent models. Competition and optimization will continue to drive costs down.
Show threadJorge Salvador CaffarenaFeb 5
@stroughtonsmith if it becomes free, it surely is game over for the technology. Big Tech is not going to allow this to not be anything other than a thing to sell and make people dependent on. If they cannot use it for that, they will instead do everything in their power to make it go away.
Show threadsoftmausFeb 5
@stroughtonsmith Every time I use a LLM for coding, it still fails in (sometimes very) subtle ways. Every single time. I can now, in 2026, only diagnose a skill issue: either on my side – or, not *that* much more unlikely, on everybody else’s 🫠
Show threadKirk ReynoldsFeb 5
@stroughtonsmith certainly not “free” but a loaded Mac Studio can run a decent sized LLM model locally.
Show threadKirk ReynoldsFeb 5
@stroughtonsmith I worked for AWS and having essentially unlimited access to Claude models really spoiled me last year. I dabbled with ObjC many moons ago, always wanted to learn Swift (I’m a web dev), but now? I know enough to review the code and have good tests but why bother writing by hand.
Show threadAwaxFeb 5

@stroughtonsmith and the $200/mo plan is massively subsidized.

If you were to use raw tokens for that, add a 0 at least.

If there are no massive gains in inference soon, I expect a big price shock around 2027 and all of us, hooked to the agent doing the boring part of actually writing code, will be in trouble.