I think the person you are responding to is not thinking visually. They basically seem (to me) to think reformat-flowed fixes this, and that having the view of a web page alter because you open a book, is "not a bad thing" when you (and I) are of the view, if you maintain the aspect ratio and simply decimate how many pixels are available to show it, the actual "change" in the layout is kept to a minimum WHICH IS THE INHERENT GOOD HERE -the whole point of the A, B and C series is that the scaling function preserves the ratio of sizes of the contents, under the quality change of bigger or smaller fidelity of presentation.

Unless there is some upsight I am missing, I think the OP just "doesn't get it"

it's a neat tidbit, but not important in the slightest imo. Probably helps with smoothly transitioning between modes, but that's not been a particular pain from my foldable use.

^^This.

Despite all the responsive design tools and declarative layouts to ensure a great layout even on an oddball resolution... the fact is that in practice it's nontrivial, and remember that the companies that make most of the apps you use have finite design and QA budgets. They need to actually use the resolution in question in order to really do a good job of designing for it, and giving them double the work, for a $2000 and up phone which probably won't be super highly adopted, is a recipe for getting apps that end up with layouts that aren't optimized properly on one (or both) of the screen sizes.

This is already something every app needs to deal with on iPad, where users can arbitrarily resize apps and windows. And apps that support landscape layout on phones have always needed to support their UI being rendered in different aspect ratios.

At WWDC this year, Apple introduced a tool[0] to let developers arbitrarily resize their simulated iOS device screens.

Flexibility and adaptivity are more front-and-center for iOS devs than ever.

[0]https://developer.apple.com/documentation/xcode/configuring-...

I agree it will feel super nice to go from the front screen to the dual screen and have nothing "move". And similarly it will feel "mildly infuriating" if it doesn't do that.

I also think that I (personally) don't need a front screen and would love to have whatever cost savings or improvements would come if there weren't one. This last sentence is of course a me thing, but I mention it because I think that if people start on the front screen and then open the Duo, they may just want the full screen app or something else entirely. I'm not sure the use case of being in your banking app device folded, deciding midway through flow to open it, and wanting to be in the same UI is really what I want. The part I question is what's going on that step 2 came about—I think it's either you want to go into more depth on it or you're just opening the device the way you would had you not been in your banking app.

The case where I open it to find the app using half the screen and then I have to press something or drag something to make it full screen is not that great (and isn't great today with current iPad window resizing). The best case I can think of for wanting the app in the same size format when I open it is for is something like multitasking, I guess we'll see how that looks or feels and how you get the second app open (or whether it's very common use case anyway).

In general, I've long felt the folding tech is for tablet use cases not for phone use cases. I think Apple's foray (finally) into it more or less validates that. Even though there will be a meaningful number of people buying it to replace their phone, I think this is largely because their phone use is already tablet use case-y (for entertainment especially). I assume many people will also buy it as a(n expensive) tablet replacement in addition to their phone, which is perhaps related to the timing of iPhone Handoff (same SIM on two phones) too.

You are not answering the parent comment. If the original aspect ratio was a square, making the "full screen" aspect ratio 1:1, then folded out it would have aspect ratio 2:1, fitting two squares side by side.

The sqrt(2) aspect ratio allows a portrait full app to be scaled up to the exactly to the folded out screen. But does anyone want that? You probably want to fit more content on the bigger screen, so some layout necessarily changes.

But its two states. What do you mean “all the way down?”

Yes, I do understand the issue with the aspect ratio, which is indeed good design, but parent comment's example is that "you can run two apps side by side" is the tautology. Well, at least since the invention of double-entry bookkeeping and getting rid of Archimedian phone design.

What app is going to design to flow nicely with a iPhone Duo but not a iPhone 18? Unless Apple has a 1.4:1 ratio across their entire product line, app designers have to deal with variation.

Also, when you rotate the device, the ratio changes. This is especially common when unfolding a foldable.

But you still do need to support different aspect ratios if you want your app to work on any other iPhone models, because many of them differ.

Even if it were true you would also have to design the app for when the device is rotated.