> (even with QT you still need to adjust for conventions, spacing etc...)

That is what I'm talking about: SwiftUI automatically uses the recommended conventions for spacing, padding, etc. which are different for macOS vs. iOS etc., and it also takes user environment settings into account, like font sizes and other accessibility options.

It can do this only because Apple exercises such tight control over all platforms. When everything is developed under the same roof, it is significantly easier to make it, "Just work." On the other hand, making three, independently-developed platforms look the same is nearly impossible. On a windows or linux box, you cannot guarantee things like screen resolution, ppi, dimensions, specs, compatibility, and the innumerable other things that cause trouble.

There are almost no technical reasons, only political, for why we don't have a truly cross-platform, truly native UI framework by now.

The whole situation is bizarre and comical if you look at it from a distance:

Everybody ALREADY puts tremendous effort in making sure things look and work the same everywhere: Browsers!

Not just Apple, Google, Microsoft and Mozilla, but the thousands of third-party maintainers (like yes Electron) in this newly-created circle of Hel that is the JavaScript ecosystem.

And now we're trying to turn the browsers into operating systems!!

Everyone keeps trying to reinvent a wheel that doesn't travel very far to begin with (see all the missing features from web apps that native apps get, being discussed on this page.)

I don't think it's possible to do it in a way that consistently looks good. I've been around my fair share of cross platform frameworks and worked at companies that built them commercially, they never work beyond apps that aren't supposed to look great.

Qt does that, too, but that is not nearly enough if you really want to make pixel- and interaction- perfect things. A "native" macos app is fundamentally different from a "native" windows app. Dock vs systray, different usage of menus, mouse and keyboard. Different widgets - Windows does not use baloon widgets and sheets. etc etc...

> A "native" macos app is fundamentally different from a "native" windows app.

The visual and interactive differences between a macOS app and a Windows app are actually less stark than the differences between a macOS app and a watchOS app (crown) or a tvOS app (remote), but so far, despite its early bugs and limitations, SwiftUI does a great job of outputting the native controls on all [of Apple's] platforms.

Things like NavigationViews and TabViews produce different beasts on macOS, iOS, iPadOS, and tvOS, from the same code.

See WWDC 2019: SwiftUI On All Devices: https://developer.apple.com/videos/play/wwdc2019/240/

Unfortunately swift doesn't have a meaningful windows story, and giving up on 100s of millions of users is less than ideal for most "crossplatform" contexts. :/

Swift is open-source at least, and I expect/hope SwiftUI will be too once the "secret" Swift features it relies on, have matured.

So even if Apple doesn't want to port SwiftUI, maybe other people could.