Structures, commonly known as structs, are fundamental building blocks in Swift programming. They allow developers to create custom, value-type data types that encapsulate related properties and methods.

What are Swift Structures?

A structure in Swift is a value type that can store multiple related properties and define methods to provide functionality. Unlike classes, structs are copied when passed around, making them ideal for representing simple data types.

Defining a Structure

To define a structure in Swift, use the struct keyword followed by the structure name. Here's a basic example:

struct Person {
    var name: String
    var age: Int
}

This creates a Person struct with two properties: name and age.

Creating and Using Structures

Once defined, you can create instances of your structure and access its properties:

let john = Person(name: "John Doe", age: 30)
print(john.name) // Output: John Doe
print(john.age)  // Output: 30

Methods in Structures

Structures can also contain methods to perform actions or computations. Here's an example:

struct Rectangle {
    var width: Double
    var height: Double
    
    func area() -> Double {
        return width * height
    }
}

You can then use this method on an instance of the structure:

let rect = Rectangle(width: 5.0, height: 3.0)
print(rect.area()) // Output: 15.0

Mutating Methods

By default, methods in structures cannot modify the structure's properties. To allow modification, use the mutating keyword:

struct Counter {
    var count = 0
    
    mutating func increment() {
        count += 1
    }
}

Benefits of Using Structures

Value semantics: Structures are copied when assigned or passed as arguments, preventing unintended side effects.
Performance: Structures are generally faster than classes for simple data types.
Thread safety: Due to their value semantics, structures are inherently thread-safe.
Simplicity: Structures don't support inheritance, making them simpler to use and reason about.

When to Use Structures

Consider using structures when:

Encapsulating simple data types
Implementing value semantics is desired
Inheritance is not needed
The data model is small and self-contained

Related Concepts

To further enhance your understanding of Swift structures, explore these related topics:

By mastering Swift structures, you'll be able to create efficient, thread-safe, and easy-to-use custom types in your Swift applications.