Friday, September 18, Apple put the first beta of Xcode 27.1 online. Nothing spectacular for anyone who doesn't code, except that this version adds one precise thing: what it takes to make applications for the iPhone Duo, a phone that won't go on sale until October 23, with preorders opening on the 16th.

In other words, Apple is handing out the hammer and nails three weeks before delivering the wall. And that's the right way to do it, even if it looks disorganized from the outside.

What's really in the beta

Three things, and the third is the one that matters. Updated development kits, meaning the bits of code we assemble to talk to the device. A simulator, which runs a fake version of the phone on your Mac so you can test without hardware. And in that simulator, support for the device's new positions and orientations, because folding a phone in half creates situations that no existing tool knew how to describe.

A crappy little detail that occupied the forums all day Friday: the Duo simulator doesn't appear if you've stayed on iOS 27.0. You have to go and get the 27.1 module manually, in Xcode's settings, under Components. Once that's done, you create the simulator from the command line with xcrun simctl create, and off you go. One developer said he had fifty applications to run through it again.

The pattern is laid out on the workbench, the fabric hasn't been cut yet. That's exactly what Apple has just done

Why deliver the tools before the product

Because a phone whose applications aren't ready is an unsellable phone. This isn't a figure of speech: when the first big screens arrived, then when notches ate into the top of the display, poorly adapted applications ended up with buttons off the screen or text cut off, and the reviews in the stores made sure everyone knew about it.

Apple had committed to this by the end of September, and you have to give them credit for this point, they're sticking to the schedule. The beta of version 27.2 had even come out a few days earlier in the week, so there are two projects under way in parallel. For someone who develops, this is the right problem to have: an imperfect simulator three weeks early is better than perfect hardware on the day it goes on sale with nothing to go with it.

And it comes after a busy start to the season on Apple's side, with two releases on the same Monday, September 14: iOS 27 arrived with a Siri that's late in Europe and macOS 27 buried Intel Macs. The Duo is arriving in the middle of all that, with its own version of the system.

Two screens, that's not just one big screen

That's the difficulty the simulator exists for, and that's where the devs are going to suffer. A phone application lives in a rectangle the size of your hand. Here, it has to accept living in two different rectangles depending on whether the device is folded or open, with proportions that aren't the same, and move from one to the other while the user is looking at it.

Second layer: an application compiled with the previous generation's tools works, but without taking advantage of anything. To make the most of the big inner screen, you have to target iOS 27.1 and later, which means reworking the layouts, not just changing a version number.

And a rumor going around in the Chinese leak scene adds a layer that I find delicious: an angle sensor around 30 degrees would decide whether to switch between the outer screen and the inner screen, with a change in power and cooling policy as a result. Translation: the folded half doesn't heat up like the unfolded half, and the software has to know it. If that's true, it means that applications will have to behave differently depending on the tilt, and that nobody had ever had to write that before.

One device, two screen sizes, and an application that has to manage both

The part that interests you if you don't code

The phone is called iPhone Duo, it was announced on September 9, and it's a hinged foldable, like a book: a 5.4-inch outer screen for one-handed use, a 7.6-inch inner screen when you open it, and the two halves form a continuous frame with no misalignment. Apple presents it as its thinnest iPhone once opened, which is the funniest sentence in the spec sheet, because a folded device is precisely twice as thick as another one.

The price starts at $1,999. Preorders open on October 16, deliveries on the 23rd, and the device comes with iOS 27.1, a version of the system made for it before being reattached to the rest of the lineup later.

Three dates to remember, and a single price line. You have three weeks to decide

So yes, two thousand dollars. But remember what you could buy for that price ten years ago, and look at what you have in your pocket today. The question isn't whether it's reasonable, it's how many people will answer yes. And as usual, the answer will be visible in the first three weeks, on resale sites.

What interests me is the rest of the developer schedule. They have three weeks to adapt, and the real test won't be in the simulator: it will be in the pockets of those who open it on October 23 and see which apps know what to do with the extra half-screen.