Creating a good cross-platform
GUI framework is probably harder
than creating a good cross-platform
language.
Way way way way way harder, I'd think. It's basically never been done in the modern era. All the successful ones from the past look (and work) like garbage on a modern desktop computer (I use gnucash for my dad's business, ha ha).
SwiftUI is an interesting re-think, though, and as a Windows 10 user, I can tell you that the current "native" experience sucks green potatoes. There are like 9 or 12 different UI technologies I must interact with each month. All with different text sizes and massively inconsistent UI paradigms.
So I think there is an opportunity here.
But, I bet SwiftUI → Web will come first. And if that happens, SwiftUI on Windows, and desktop Linux, will be a no-brainer and will happen.
And if it doesn't happen, then probably SwiftUI won't matter outside of the Apple ecosystem, and that will mean Swift won't matter much in the end, either. (EDIT: I don't mean Apple need do this and I don't expect they will. But SwiftUI is just an API; anybody could port it to whatever environment they want, and there are already some nascent third-party efforts to implement it for HTML/web.)
Full disclosure disclaimer: former NewtonScript programmer
I think the opportunity is particularly on how SwiftUI has been implemented in iOS, iPadOS and macOS, by relying on the native UI of each platform and providing a common abstraction for developers.
Instead of providing the same UI that works badly on every device, SwiftUI interprets each concept differently according to the platform.
For example, a Toggle in an iOS and iPadOS app looks like a on/off switch, while on macOS it's rendered as a checkbox. A Picker has is scrolling wheel on iOS but it's shown as radio boxes or a drop-down menu on macOS.
Navigation is also the same. On iOS, a NavigationView offers the drill-down navigation common to iPhone apps, while on macOS it creates a split master-detail interface.
Each implementation does so by using the native UI framework of each platform under the hood, UIKit on iOS, and AppKit on macOS. I don't know how UI development works on Windows, but my speculation is that a SwiftUI implementation would work the same way.
I can’t comment on SwiftUI in particular, but I’ve found that a lot of things like this tend to break down in most other cross platform GUI frameworks, falling into a kind of uncanny valley, where the experience ends up being either:
1. Native feeling, but sufficiently inflexible that only very simple, common UI patterns can be implemented
2. An “uncanny valley” native ui, where things are almost native but often feel wrong in subtle ways
I think that’s why Electron has succeeded where so many cross platform UI frameworks failed: it’s so obviously not native that it doesn’t fall into that “uncanny valley” anymore
The way they have implemented it for even their own "cross-platform" needs (where the "platforms" are really basically different versions of the same OS) works very well — the sickening, jaw-droppingly awful apps from Twitter, JIRA, etc that use the "Catalyst" system of porting iPad apps to Mac shows why the approach is really necessary.
(Those apps bring iPad metaphors to the Mac, so what should be a single interaction, picking something from a menu, is a jarring series of taps, swipes, and animated fuckery.)
If that "render the concept using the OS's native widgets" approach was necessary even for cross iOS-macOS apps, it will be even more necessary across Mac and Windows, where a lot of the UI conventions are wildly different, and sometimes literally the opposite (e.g. the standard placement of buttons).
And it's obviously the only way it could work for web apps.
Sun tried with Swing.. and they were not a second tier company at the time. Also previous versions of OSX (before the rename to macOS) included a special theme of Swing to make apps to look more native in OSX (Jobs was happy to announce that OSX supported Java... when Java was sexy).
Then when RIA was a buzzword Sun/Oracle tried to modernise Swing without success. Today the only big Swing apps that I know are Netbeans and maybe IntelliJ (but I think that IntelliJ has tons of customisations on top of it).
So is even hard for a big company too. I guess the problem is that the framework will be always behind the OS, and you need to recreate all the styles or to create a thin layer with the common denominator between platforms.
Is interesting that different approaches to cross-platform UI (draw all vs thin layer) goes back to Smalltalk. AFAIK the idea of Swing drawing all the UI came from VisualWorks, while the thin layer of SWT came from IBM VisualAge
>Sun tried with Swing.. and they were not a second tier company at the time.
Swing was ill thought from the beginning. Over-engineered, too complex, slow (as if there were 2-3 layers between the code and the drawing engine), and looking bad in every platform...
>So is even hard for a big company too. I guess the problem is that the framework will be always behind the OS, and you need to recreate all the styles or to create a thin layer with the common denominator between platforms.
I'm not so sure that's a problem. You can always look different than the OS, and do a good job at it. Millions use the Adobe Creative Suite, Cubase, Pro Tools, StudioPro, etc, and their non-native UI is the last thing they complain about...
Heck, even Electron apps do that. Why wouldn't users like apps that look different from the OS, the way Electron apps do, but with far less memory usage, much speedier drawing, and better integration options with native widgets when needed?
SwiftUI is an interesting re-think, though, and as a Windows 10 user, I can tell you that the current "native" experience sucks green potatoes. There are like 9 or 12 different UI technologies I must interact with each month. All with different text sizes and massively inconsistent UI paradigms.
So I think there is an opportunity here.
But, I bet SwiftUI → Web will come first. And if that happens, SwiftUI on Windows, and desktop Linux, will be a no-brainer and will happen.
And if it doesn't happen, then probably SwiftUI won't matter outside of the Apple ecosystem, and that will mean Swift won't matter much in the end, either. (EDIT: I don't mean Apple need do this and I don't expect they will. But SwiftUI is just an API; anybody could port it to whatever environment they want, and there are already some nascent third-party efforts to implement it for HTML/web.)
Full disclosure disclaimer: former NewtonScript programmer