Your first SwiftUI Mac OS App

First we need to open XCode. I'm using the XCode 12 beta so yours may look a bit different.

Our application itself is mostly contained in the ContentView.swift file. This includes a PreviewProvider (kind of like a built-in storybook) as well as Text with the default padding.

import SwiftUI

struct ContentView: View {
    var body: some View {
        Text("Hello, world!").padding()
    }
}

struct ContentView_Previews: PreviewProvider {
    static var previews: some View {
        ContentView()
    }
}

If we click resume on the preview pane, we see the preview show us our ContentView

The container, MyFirstMacAppApp.swift, bootstraps our app with a Scene.

import SwiftUI

@main
struct MyFirstMacAppApp: App {
    var body: some Scene {
        WindowGroup {
            ContentView()
        }
    }
}

After clicking the play button and running the application, we can see that we have a window with some text and padding.