How do I add a toolbar to a macOS app using SwiftUI?

Question

I am trying to add a toolbar inside the title bar to a macOS app using SwiftUI, something similar to what is shown below.

I am unable to figure out a way to ac

Answer 1

UIKit + Catalyst

https://developer.apple.com/documentation/uikit/uititlebar

    func scene(_ scene: UIScene, willConnectTo session: UISceneSession, options connectionOptions: UIScene.ConnectionOptions) {

        guard let windowScene = (scene as? UIWindowScene) else { return }
        let window = UIWindow(windowScene: windowScene)

        if let titlebar = windowScene.titlebar {

            //toolbar
            let identifier = NSToolbar.Identifier(toolbarIdentifier)
            let toolbar = NSToolbar(identifier: identifier)
            toolbar.allowsUserCustomization = true
            toolbar.centeredItemIdentifier = NSToolbarItem.Identifier(rawValue: centerToolbarIdentifier)
            titlebar.toolbar = toolbar
            titlebar.toolbar?.delegate = self

            titlebar.titleVisibility = .hidden
            titlebar.autoHidesToolbarInFullScreen = true
        }

        window.makeKeyAndVisible()

    }

#if targetEnvironment(macCatalyst)
let toolbarIdentifier = "com.example.apple-samplecode.toolbar"
let centerToolbarIdentifier = "com.example.apple-samplecode.centerToolbar"
let addToolbarIdentifier = "com.example.apple-samplecode.add"

extension SceneDelegate: NSToolbarDelegate {

    func toolbar(_ toolbar: NSToolbar, itemForItemIdentifier itemIdentifier: NSToolbarItem.Identifier, willBeInsertedIntoToolbar flag: Bool) -> NSToolbarItem? {
        if itemIdentifier == NSToolbarItem.Identifier(rawValue: toolbarIdentifier) {
            let group = NSToolbarItemGroup(itemIdentifier: NSToolbarItem.Identifier(rawValue: toolbarIdentifier), titles: ["Solver", "Resistance", "Settings"], selectionMode: .selectOne, labels: ["section1", "section2", "section3"], target: self, action: #selector(toolbarGroupSelectionChanged))

            group.setSelected(true, at: 0)

            return group
        }

        if itemIdentifier == NSToolbarItem.Identifier(rawValue: centerToolbarIdentifier) {
            let group = NSToolbarItemGroup(itemIdentifier: NSToolbarItem.Identifier(rawValue: centerToolbarIdentifier), titles: ["Solver1", "Resistance1", "Settings1"], selectionMode: .selectOne, labels: ["section1", "section2", "section3"], target: self, action: #selector(toolbarGroupSelectionChanged))

            group.setSelected(true, at: 0)

            return group
        }

        if itemIdentifier == NSToolbarItem.Identifier(rawValue: addToolbarIdentifier) {
            let barButtonItem = UIBarButtonItem(barButtonSystemItem: UIBarButtonItem.SystemItem.add, target: self, action: #selector(self.add(sender:)))
            let button = NSToolbarItem(itemIdentifier: itemIdentifier, barButtonItem: barButtonItem)
            return button
        }

        return nil
    }

    @objc func toolbarGroupSelectionChanged(sender: NSToolbarItemGroup) {
        print("selection changed to index: \(sender.selectedIndex)")
    }

    @objc func add(sender: UIBarButtonItem) {
        print("add clicked")
    }

    func toolbarDefaultItemIdentifiers(_ toolbar: NSToolbar) -> [NSToolbarItem.Identifier] {
        [NSToolbarItem.Identifier(rawValue: toolbarIdentifier), NSToolbarItem.Identifier(rawValue: centerToolbarIdentifier), NSToolbarItem.Identifier.flexibleSpace,
            NSToolbarItem.Identifier(rawValue: addToolbarIdentifier),
            NSToolbarItem.Identifier(rawValue: addToolbarIdentifier)]
    }

    func toolbarAllowedItemIdentifiers(_ toolbar: NSToolbar) -> [NSToolbarItem.Identifier] {
        self.toolbarDefaultItemIdentifiers(toolbar)
    }

}
#endif