Variables and Constants

Variables

What are Variables?

Variables are mutable storage locations that can hold different types of values. They are declared using the var keyword.

var name = "John"
var age = 30

Changing Variable Values

Since variables are mutable, you can change their values after they have been declared.

var score = 90
score = 95  // Changing the value of 'score'

Constants

What are Constants?

Constants are immutable storage locations. Once you set a value for a constant, it can't be changed. They are declared using the let keyword.

let pi = 3.14159

When to Use Constants

It's a good practice to use constants when you know that a value won't change throughout the scope of the code. This makes the code safer and easier to understand.

let maximumAttempts = 3  // This value won't change

Type Inference and Annotation

Swift uses type inference to automatically determine the type of a variable or constant. However, you can also explicitly specify the type using type annotation.

var userName: String = "Alice"  // Type annotation
let year: Int = 2023

Conclusion

Understanding variables and constants is fundamental to becoming proficient in Swift. Variables offer flexibility by allowing you to change their values, while constants provide safety by ensuring that their values remain fixed. Knowing when to use each is key to writing efficient and readable Swift code.