Creating and Running .swift Files

Write your Swift code in a text editor and save the file with a .swift extension. Save the file using the UTF-8 character encoding.

sample_hello.swift

import Foundation

let name = "Swift"
let version = 5

print("Language: \(name)")
print("Version: \(version)")
print("Hello, World!")

Swift allows you to write code directly at the top level and run it like a script. You can also compile it to generate an executable file.

You can write comments (notes) in a .swift file. Comments are ignored by the compiler, so they are useful for leaving descriptions or notes about the code.

import Foundation

/*
  A nestable comment.
  /* You can nest comments like this. */
  This is a Swift-specific feature.
*/
let message = "Hello, World!"
print(message)

Swift's multi-line comments (/* */) support nesting. This is a Swift-specific feature not found in many other languages.

Run directly with the swift command

The swift command lets you run a .swift file directly like a script without compiling. It is handy for quick checks.

hello.swift

swift hello.swift
Language: Swift
Version: 5
Hello, World!

Compile with swiftc and run

The swiftc command compiles a .swift file and generates an executable, which you then run. The -o option specifies the output filename.

swiftc hello.swift -o hello
./hello

When compilation succeeds, an executable file with the specified name is generated.

Language: Swift
Version: 5
Hello, World!

Comparison of run methods

A .swift file is simply a plain text file. You can create one by writing Swift code in a text editor and saving it with a .swift extension.

Swift has two ways to run code. The swift command lets you run directly without compiling for quick checks. Use swiftc to compile when you need a distributable executable. For day-to-day development, running directly with swift is convenient for quick verification.

For recommended editors and environment setup, see Setup.