Swift Playgrounds

What a Playground Is

A Swift playground is an interactive scratchpad, built into Xcode and the standalone Swift Playgrounds app, where each line of code runs and shows its result immediately in a sidebar. It is designed for quickly experimenting with ideas without creating a full project.

Example: What a Playground Is

let message = "Playgrounds show results instantly"
print(message)

Command-Line Scripts as a Playground Alternative

Outside of Xcode, a plain .swift file run with the swift command gives similar fast feedback: write top-level statements and run the file to see printed output immediately, which is exactly how the examples in this course work.

Note: Every example in this course can be run this same way: save it as a .swift file and run swift filename.swift.

Example: Command-Line Scripts as a Playground Alternative

let numbers = [1, 2, 3, 4]
let doubled = numbers.map { $0 * 2 }
print(doubled)

Good Uses for a Playground

Playgrounds are best for testing a small piece of logic, exploring a new API, or checking how a language feature behaves before committing it to a larger codebase, since you get instant visual feedback without the overhead of building a full app.

Example: Good Uses for a Playground

for n in 1...5 {
    print("Testing square of \(n): \(n * n)")
}