Sebastiaan de With, in a wonderfully-illustrated piece (a) examining, in detail, where iOS UI has been, and (b) speculating, with detailed mockups, where he thinks/hopes it’s about to go, starting at WWDC next week:

I’d like to imagine what could come next. Both by rendering some UI design of my own, and by thinking out what the philosophy of the New Age could be.

A logical next step could be extending physicality to the entirety of the interface. We do not have to go overboard in such treatments, but we can now have the interface inhabit a sense of tactile realism.

Philosophically, if I was Apple, I’d describe this as finally having an interface that matches the beautiful material properties of its devices. All the surfaces of your devices have glass screens. This brings an interface of a matching material, giving the user a feeling of the glass itself coming alive. [...]

I took some time to design and theorize what this would look like, and how it would work. For the New Design Language, it makes sense that just like on VisionOS, the material of interactivity is glass.

I hope, very much, that what Apple has been working on is along the lines of what de With has mocked up. It both looks great (and better than what we have now) and makes sense. I also agree with him that it would be a competitive advantage for Apple to establish a new visual design language that no existing design tools can create. You can’t make the sort of things de With is describing with Figma. Competitors could (and I guarantee will) superficially copy the look, but not the interactive responsiveness of lighting effects.

In a profound way, a UI language comprised of glossy and matte glass, running on phones and tablets that themselves are made of glossy and matte glass, would hark back to the early days of Mac OS X, when the “lickable” translucent Aqua UI theme felt of a piece with the colorful translucent plastic enclosures of the iMac, PowerMac, and iBook. Right down to the pinstripes. (Apple never did make an Aqua-style PowerBook along those lines, instead going straight from classic black plastic to the Titanium PowerBook G4, the styling of which augured the post-Aqua look-and-feel of Mac OS X 10.5 Leopard and the much-beloved 10.6 Snow Leopard.) I’ve been clamoring for buttons to look like buttons again ever since iOS 7.

But as much as I truly love de With’s mockups, they’re all for iOS. What I’m left unsettled by is my failure to imagine how this design language could be brought to the Mac. Macs aren’t made of glass; they’re all made of aluminum. But the main difference is that the way many of us use MacOS is with a lot of stacked windows atop each other. The last thing MacOS needs is more transparency/translucency than it already has. Some depth to its UI controls, though? That’s something MacOS is in almost desperate need of. A horse, a horse, my kingdom for a Mac UI theme where you can tell, instantly, whether a button is enabled or disabled or which item in a tabview controller is selected.

We’ll soon see.