recompose: Skill for Claude Code

Native macOS Patterns for Web Developers

This is a reference guide for the macOS-specific patterns that have no web equivalent. When building a native macOS app, these are the things that trip up everyone coming from web development. The AI should consult this before generating macOS code to avoid confidently producing patterns that don't work.

Menu Bar Apps

There are two approaches. Use MenuBarExtra for simple menus, NSStatusItem for full control.

SwiftUI MenuBarExtra (simple)

@main
struct MyApp: App {
    var body: some Scene {
        MenuBarExtra("MyApp", image: "MenuBarIcon") {
            MenuBarView()
        }
    }
}

This creates a menu-bar-only app. The menu content is a standard SwiftUI view. For a popover-style menu bar app (richer UI than a plain menu), use the .window style:

MenuBarExtra("MyApp", image: "MenuBarIcon") {
    PopoverContentView()
}
.menuBarExtraStyle(.window)

AppKit NSStatusItem (full control)

For custom menus, dynamic icons, or complex interactions:

let statusItem = NSStatusBar.system.statusItem(withLength: NSStatusItem.squareLength)
if let button = statusItem.button {
    let icon = NSImage(named: "MenuBarIcon")!
    icon.size = NSSize(width: 18, height: 18)
    icon.isTemplate = true  // CRITICAL: adapts to dark/light mode automatically
    button.image = icon
}

let menu = NSMenu()
menu.addItem(NSMenuItem(title: "Settings...", action: #selector(openSettings), keyEquivalent: ","))
statusItem.menu = menu

isTemplate = true is essential. Without it, your icon will be invisible in light mode or look wrong in dark mode.

NSPopover for Rich Menu Bar Content

For a popover attached to the menu bar icon (like Bartender, iStatMenus):

let popover = NSPopover()
popover.contentSize = NSSize(width: 300, height: 400)
popover.behavior = .transient  // auto-closes when clicking outside
popover.contentViewController = NSHostingController(rootView: MyPopoverView())

// Show from the status item button:
if let button = statusItem.button {
    popover.show(relativeTo: button.bounds, of: button, preferredEdge: .minY)
}