Basics

• Code starts in the global scope, just like in Python.

Comments

// This is a comment.

/* This is also a comment
but is written over multiple lines. */

Use of ;

• Swift doesn’t require you to write a semicolon ( ; ) after each statement in your code, although you can do so if you wish.

• Semicolons are  required if you want to write multiple separate statements on a single line:

let cat = "🐱"; print(cat)
// Prints "🐱"

Keywords

let (constant)

• Not modifiable at any time

let a = 10

let a = [10, 20, 30]
a.append(10) // Crash.

var

• Modifiable at any time

var a = 10

Multiple declaration

var x = 0.0, y = 0.0, z = 0.0

var red, green, blue: Double