In Swift, constants are values that never change while variables are values that can change. For both constants and variables, different types of values can be assigned including strings, integers, arrays, etc. A constant uses ‘let’ while a variable uses ‘var’.
A player’s device in a game could be a constant if it won’t change.
let playerDevice = "iPhone"
This constant stores the player’s device as a string. Because it is a constant, it’s value cannot change.
playerDevice = "iPad" // This will produce an error.
A changing value, such as a score, can be stored as a variable.
var score = 20
This variable stores the player’s score as an integer. Later in code, this value can change. For example:
score = 21
There are many more data types than just strings and integers in constants and variables.
String: Usually text or a combination of text and numbers. Emojis can also be used in a string data type.
Int: Integers are whole numbers that don’t contain decimal places like 2, 73, -29, etc.
Double and Float: These are numbers with decimal places like 1.75, 9.49, etc. Double can contain many more decimal places than float for a more precise measurement.
Bool: This is a very simple data type, either true or false.
There are other types of data, but these are the most common.