Hi everyone,
I've been working on StateUI:
https://github.com/idexus/StateUI
It started as an experiment — how far could Swift go as the application and UI language outside the Apple stack, without building yet another cross-platform widget toolkit? Swift does the declarative UI, the state and the reconciliation; .NET MAUI provides the controls and the platform layer on iOS, Android, Windows and Mac Catalyst.
A complete application - a window, two tabs, and the state that moves them:
enum Tab: Hashable, CaseIterable {
case counter
case list
}
struct GalleryApp: Application {
func createWindow() -> Window { MainWindow() }
}
struct MainWindow: Window {
@State private var tab: Tab = .counter
var title: String? { "StateUI" }
var content: Page {
TabbedPage(Tab.allCases) { which in
switch which {
case .counter: CounterPage(tab: $tab)
case .list: ListPage()
}
}
.selection($tab)
}
}
struct CounterPage: ContentPage {
@Binding var tab: Tab
@State private var counter = 0
var title: String? { "Counter" }
var content: Element {
VStack {
Label("Count: \(counter)")
.fontSize(20)
.horizontalTextAlignment(.center)
Button("Increment")
.cornerRadius(8)
.onClicked { counter += 1 }
Button("Go to the list")
.onClicked { tab = .list }
}
.spacing(20)
.padding(24)
}
}
struct ListPage: ContentPage {
var title: String? { "List" }
var content: Element {
CollectionView(1...100) { number in
Label("Row \(number)")
.fontSize(16)
.padding(16, 12)
}
.itemSize(44)
}
}
Swift keeps the rendered tree, tracks which state each view read, and reconciles. What crosses to C# is a sparse binary patch — only what changed — and the MAUI side applies it to the native controls already on screen.
It is at 0.2.0 — every control MAUI 10 draws, a gallery app that exercises each one, and 660 Swift plus 512 C# tests. The API still moves between versions, and the 0. in front is meant literally.
I'm curious what people make of the broader idea: Swift as the declarative layer over an existing native UI runtime, rather than a new widget stack underneath it.
