Working with Class and Struct Instances

1. Introduction

Goal: In this tutorial, we aim to provide a practical and comprehensive understanding of how to work with class and struct instances in Swift.

Learning Outcomes: By the end of this tutorial, you will be able to:
- Understand class and struct instances in Swift
- Create instances of a class and struct
- Manipulate properties and methods of these instances

Prerequisites: This tutorial assumes you have a basic understanding of the Swift programming language. If not, I recommend going through Swift's official documentation.

2. Step-by-Step Guide

Understanding Class and Struct Instances

In Swift, both classes and structs can have properties and methods. An instance of a class or a struct is a realization of the class or struct. You can create an instance and manipulate its properties and call its methods.

Creating Instances

To create an instance of a class or a struct, you use the class or struct name followed by parentheses ().

Manipulating Properties

After creating an instance, you can access its properties using the dot . syntax, and you can modify them if they are not declared as constant with let.

Calling Methods

Methods can also be called on instances using the dot . syntax.

3. Code Examples

Example 1: Creating and Manipulating Instances

Here we'll create a simple struct and a class, create instances of them, and manipulate their properties.

// Defining a struct
struct Car {
    var color: String
    var brand: String
}

// Creating an instance of Car struct
var myCar = Car(color: "Red", brand: "BMW")
print(myCar.color) // prints "Red"

// Changing the property of the instance
myCar.color = "Blue"
print(myCar.color) // prints "Blue"

// Defining a class
class Phone {
    var model: String
    var brand: String

    init(model: String, brand: String) {
        self.model = model
        self.brand = brand
    }
}

// Creating an instance of Phone class
var myPhone = Phone(model: "iPhone 12", brand: "Apple")
print(myPhone.model) // prints "iPhone 12"

// Changing the property of the instance
myPhone.model = "iPhone 13"
print(myPhone.model) // prints "iPhone 13"

4. Summary

In this tutorial, we have learned about class and struct instances in Swift. We have seen how to create instances and manipulate their properties. We also looked at how to call methods on instances, though we didn't define any methods in our examples.

The next step in your learning journey could be exploring more about methods in classes and structs, including instance methods and type methods.

5. Practice Exercises

Exercise 1: Create a struct Book with properties title and author, and create an instance of it.

Exercise 2: Create a class Laptop with properties model and brand, and create an instance of it. Then, change the model of the instance.

Solutions:

Exercise 1:

struct Book {
    var title: String
    var author: String
}

var myBook = Book(title: "1984", author: "George Orwell")
print(myBook.title) // prints "1984"

Exercise 2:

class Laptop {
    var model: String
    var brand: String

    init(model: String, brand: String) {
        self.model = model
        self.brand = brand
    }
}

var myLaptop = Laptop(model: "MacBook Pro", brand: "Apple")
print(myLaptop.model) // prints "MacBook Pro"

myLaptop.model = "MacBook Air"
print(myLaptop.model) // prints "MacBook Air"

Continue practicing by creating more classes and structs, and creating instances of them. Try defining your own methods in those classes and structs, and call them on the instances. Happy coding!