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In the preceding example, and for most of this book, we focused on iOS-based playgrounds. However, macOS-based playgrounds are just as useful for the macOS platform and can also be used for UI testing and experimentation.

You will find a macOS-based playground called Simple_macOS.playground that also creates a simple bar chart view in this book's GitHub repository at https://github.com/PacktPublishing/Swift-Cookbook-Second-Edition/tree/master/Chapter07/01_Using_Swift_Playgrounds_for_UI

Alternatively, you can create a new macOS-based playground and enter the following code:

1. Create a Color struct:

import PlaygroundSupport
import Cocoa

struct Color {
    let red: CGFloat
    let green: CGFloat
    let blue: CGFloat
    let alpha: CGFloat = 1.0
    
    var displayColor: NSColor {
        return NSColor(calibratedRed: red, 
                       green: green, 
                       blue: blue, 
                       alpha: alpha)
    }
}

2. Create a ...