ARC overview for memory management in Swift - Mini Project: Build & Apply

ARC overview for memory management

📖 Scenario: Imagine you are building a simple app that manages a list of books. Each book has a title and an author. You want to understand how Swift automatically manages memory for your objects using ARC (Automatic Reference Counting).

🎯 Goal: You will create a simple class for books, create instances, and observe how ARC manages memory by tracking when objects are created and destroyed.

📋 What You'll Learn

Create a class called Book with a title property

Add an initializer that prints when a Book is created

Add a deinitializer that prints when a Book is destroyed

Create a variable to hold a Book instance

Set the variable to nil to release the Book instance

💡 Why This Matters

🌍 Real World

Understanding ARC helps you write efficient Swift apps that use memory well and avoid crashes.

💼 Career

Memory management is a key skill for iOS developers to build stable and performant apps.

1

Create the Book class with a title property

Create a class called Book with a title property of type String. Add an initializer that takes a title parameter and assigns it to the property. Inside the initializer, add a print statement that says "Book titled 'title' is created".

Swift

# Create the Book class with a title property and initializer
# Your code here

Need a hint?

Remember to use self.title = title inside the initializer to set the property.

2

Add a deinitializer to the Book class

Add a deinit method to the Book class that prints "Book titled 'title' is being destroyed" when the object is removed from memory.

Swift

class Book {
    let title: String
    init(title: String) {
        self.title = title
        print("Book titled '\(title)' is created")
    }
    // Add deinitializer here
    // Your code here
}

Need a hint?

The deinit method runs automatically when the object is removed from memory.

3

Create a variable to hold a Book instance

Create a variable called myBook and assign it a new Book instance with the title "Swift Programming".

Swift

class Book {
    let title: String
    init(title: String) {
        self.title = title
        print("Book titled '\(title)' is created")
    }
    deinit {
        print("Book titled '\(title)' is being destroyed")
    }
}

// Create myBook variable and assign a Book instance
// Your code here

Need a hint?

Use var myBook: Book? = Book(title: "Swift Programming") to create the variable.

4

Set the myBook variable to nil to release the instance

Set the variable myBook to nil to release the Book instance and trigger the deinitializer.

Swift

class Book {
    let title: String
    init(title: String) {
        self.title = title
        print("Book titled '\(title)' is created")
    }
    deinit {
        print("Book titled '\(title)' is being destroyed")
    }
}

var myBook: Book? = Book(title: "Swift Programming")

// Set myBook to nil below
// Your code here

Need a hint?

Setting myBook to nil removes the last reference to the object, so ARC destroys it.