Classes are reference types in Swift - Mini Project: Build & Apply

Classes are reference types

📖 Scenario: Imagine you have a simple app that keeps track of a book's details. You want to understand how changing one book's information can affect other references to the same book.

🎯 Goal: You will create a Book class, make two variables point to the same book, change the title through one variable, and see how it affects the other variable. This will show that classes are reference types.

📋 What You'll Learn

Create a class called Book with a title property of type String

Create a variable firstBook that is an instance of Book with the title "Swift Programming"

Create a variable secondBook and assign it to firstBook

Change the title of secondBook to "Advanced Swift"

Print the title of firstBook to show it has changed

💡 Why This Matters

🌍 Real World

Understanding reference types is important when working with objects in apps, so you know how data changes affect your program.

💼 Career

Many programming jobs require knowledge of how classes and objects work, especially in Swift for iOS app development.

1

Create the Book class

Create a class called Book with a title property of type String. Initialize title using an initializer.

Swift

// Create the Book class with a title property
// Your code here

Need a hint?

Use class Book {} and add a var title: String inside. Add an init method to set the title.

2

Create firstBook instance

Create a variable called firstBook and assign it an instance of Book with the title "Swift Programming".

Swift

class Book {
    var title: String
    
    init(title: String) {
        self.title = title
    }
}

// Create firstBook instance with title "Swift Programming"
// Your code here

Need a hint?

Use var firstBook = Book(title: "Swift Programming") to create the instance.

3

Assign secondBook to firstBook and change title

Create a variable called secondBook and assign it to firstBook. Then change the title of secondBook to "Advanced Swift".

Swift

class Book {
    var title: String
    
    init(title: String) {
        self.title = title
    }
}

var firstBook = Book(title: "Swift Programming")

// Assign secondBook to firstBook
// Change secondBook's title to "Advanced Swift"
// Your code here

Need a hint?

Assign secondBook = firstBook and then set secondBook.title = "Advanced Swift".

4

Print the title of firstBook

Print the title of firstBook using print to show it has changed to "Advanced Swift".

Swift

class Book {
    var title: String
    
    init(title: String) {
        self.title = title
    }
}

var firstBook = Book(title: "Swift Programming")
var secondBook = firstBook
secondBook.title = "Advanced Swift"

// Print the title of firstBook
// Your code here

Need a hint?

Use print(firstBook.title) to see the changed title.