Apps that support iPad are 95% fine unless you do crazy custom things (which Apple has been telling developers for decades now that they shouldn’t do), and apps that are phone only are letterboxed, but still entirely usable.

How many customers do you expect to be running on Duo for the first year of its existence?

I’d be surprised if it was >0.01% for anyone. Apple wants you to drop everything to support all the bells and whistles for their new device, but even if you take 3 months to fix minor layout bugs, I don’t think it’s that big of a deal.

I have friends who dropped everything to support the Vision Pro, and I don’t think any of them felt like it was worth it in retrospect. Even the ones that got featured by Apple as a result didn’t see more than a few thousand downloads.

Fired it up to check my own app (RunnerCast) and it looks fine. The Liquid Glass menu moves from the bottom to the right side automatically both on the inner and outer screens. If you already had a layout that worked for iOS and iPadOS, things adapt fine to the inside screen and when you go split screen with two apps, the layout adapts nicely. I don't think I'll need to do a thing.

I've also noticed a flurry of recent app updates from some of the bigger apps (MLB, NYTimes, etc.) to switch to the Liquid Glass menu which I assume Apple strongly suggested they do prior to the Duo launch.

> I expect that most apps will look rather broken on release, but it will be smoothed out eventually.

I don’t think it'll be "most apps".

Apple all but told developers in June [1] to update their apps not to assume a fixed screen size.

One of the apps Apple's engineers demonstrate new features was called Origami [2]. When I watched the video, it seemed pretty clear: a device that folds was in our future.

If you’re a developer that's kept up with the latest iOS developments, you'll be in good shape for the Duo.

But if you're up to your eyeballs in technical debt using deprecated frameworks and APIs… it's probably gonna be a while for you.

[1]: https://developer.apple.com/videos/play/wwdc2026/278

[2]: "Modernize your UIKit app" — https://en.wikipedia.org/wiki/Origami

Unless Apple uses their stick (whip, or whatever else) to drive the developer community, I bet iOS will experience the same app fragmentation as Android does regarding various form factors, more so than between iPad, iPhone and iWatch already.

"You are a experienced iOS Software Engineer, your task is to migrate this application to the iPhone Duo layout...

I expect that most apps will look rather broken on release, but it will be smoothed out eventually.

Sadly, many apps will continue to look rather broken.

There are still thousands of apps that still look wrong on iPad 16 years after its release, even with the 2x button pushed, for no good reason.

I think I heard that Instygram only recently figured it out.

Most apps people actually use will look fine because there's a team of mobile devs in all big companies who get paid to keep up with Apple breaking their apps every year with their 'updates' (among other things).

I mean, don't expect advanced features like consistent smooth scrolling, non-broken UI, absence of animation flickers, cloud sync that works consistently even for paid apps developed by Apple or anybody else but other than that :)