swiftui

Overview ¶

Package swiftui loads app-owned Swift packages that expose SwiftUI content to AppKit.

The intended workflow is:

1. Put your SwiftUI code in a Swift package that builds a dynamic library.
2. Export an Objective-C-visible factory class from that package.
3. Optionally prebuild a universal dylib with go generate.
4. Optionally embed that dylib in your Go binary.
5. Use this Go package to load the embedded dylib first, then `Dir/lib<Product>.dylib`, then fall back to building the Swift package on demand from source.

The default contract expects the Swift factory class to provide `newRootViewController` and `newRootView` class methods. Those selectors use Cocoa's "new" ownership convention, so the Go caller owns the returned object and must call Release when finished with it.

Example Swift package:

import SwiftUI
import AppKit

struct ContentView: View {
    var body: some View {
        Text("Hello from SwiftUI").padding(24)
    }
}

@objc(ExampleUIBridge)
public final class ExampleUIBridge: NSObject {
    @objc public static func newRootViewController() -> NSViewController {
        NSHostingController(rootView: ContentView())
    }

    @objc public static func newRootView() -> NSView {
        NSHostingView(rootView: ContentView())
    }
}

Example Go usage:

bridge, err := swiftui.Open(swiftui.Config{
	Dir:          "/path/to/ui",
	Product:      "ExampleUI",
	FactoryClass: "ExampleUIBridge",
	EmbeddedLibrary: embeddedExampleUI(),
})
if err != nil {
	log.Fatal(err)
}
controller, err := bridge.NewViewController()
if err != nil {
	log.Fatal(err)
}
defer controller.Release()
window.SetContentViewController(controller)

Typical embedding setup:

//go:generate go run ./ui/generate.go

//go:build swiftui_embed
//go:embed ui/libExampleUI.dylib
var exampleUIDylib []byte

Callers should lock the main goroutine to the main thread before creating or using AppKit objects returned by this package.