Why classes exist alongside structs in Swift - See It in Action

Why Classes Exist Alongside Structs in Swift

📖 Scenario: Imagine you are building a simple app to manage information about books and their authors. You want to understand when to use structs and when to use classes in Swift.

🎯 Goal: You will create a struct and a class to represent books and authors, then see how they behave differently when copied or changed.

📋 What You'll Learn

Create a struct called Book with properties title and pages

Create a class called Author with properties name and booksWritten

Show how changing a copy of a Book struct does not affect the original

Show how changing a copy of an Author class affects the original

Print the results to observe the differences

💡 Why This Matters

🌍 Real World

Understanding when to use structs or classes helps you write safer and more efficient Swift code, especially in apps where data sharing and copying matter.

💼 Career

Swift developers often decide between structs and classes to optimize app performance and behavior, making this knowledge essential for iOS development jobs.

1

Create the Book struct

Create a struct called Book with two properties: title of type String and pages of type Int. Then create a variable firstBook of type Book with title "Swift Basics" and pages 200.

Swift

# Your code here

Need a hint?

Use struct keyword to define Book. Properties are declared with var.

2

Create the Author class

Create a class called Author with two properties: name of type String and booksWritten of type Int. Then create a variable firstAuthor of type Author with name "Alice" and booksWritten 3.

Swift

struct Book {
    var title: String
    var pages: Int
}

var firstBook = Book(title: "Swift Basics", pages: 200)

# Your code here

Need a hint?

Use class keyword and an initializer init to set properties.

3

Copy and change the Book struct

Create a new variable secondBook and set it equal to firstBook. Then change secondBook.pages to 250.

Swift

struct Book {
    var title: String
    var pages: Int
}

var firstBook = Book(title: "Swift Basics", pages: 200)

class Author {
    var name: String
    var booksWritten: Int
    
    init(name: String, booksWritten: Int) {
        self.name = name
        self.booksWritten = booksWritten
    }
}

var firstAuthor = Author(name: "Alice", booksWritten: 3)

# Your code here

Need a hint?

Assign firstBook to secondBook and then change secondBook.pages.

4

Copy and change the Author class and print results

Create a new variable secondAuthor and set it equal to firstAuthor. Then change secondAuthor.booksWritten to 5. Finally, print firstBook.pages, secondBook.pages, firstAuthor.booksWritten, and secondAuthor.booksWritten each on its own line.

Swift

struct Book {
    var title: String
    var pages: Int
}

var firstBook = Book(title: "Swift Basics", pages: 200)

class Author {
    var name: String
    var booksWritten: Int
    
    init(name: String, booksWritten: Int) {
        self.name = name
        self.booksWritten = booksWritten
    }
}

var firstAuthor = Author(name: "Alice", booksWritten: 3)

var secondBook = firstBook
secondBook.pages = 250

# Your code here

Need a hint?

Assign firstAuthor to secondAuthor, change secondAuthor.booksWritten, then print all values.