Adding initializers via extension in Swift - Mini Project: Build & Apply

Adding initializers via extension

📖 Scenario: You are creating a simple app that manages information about books. You want to add a new way to create book objects easily by adding an initializer through an extension.

🎯 Goal: Learn how to add a new initializer to an existing Book struct using an extension in Swift.

📋 What You'll Learn

Create a Book struct with two properties: title and author, both of type String.

Add an extension to Book that includes a new initializer which takes a single String parameter called combined.

The new initializer should split the combined string by a dash " - " and assign the first part to title and the second part to author.

Create a Book instance using the new initializer with the string "1984 - George Orwell".

Print the title and author of the created Book.

💡 Why This Matters

🌍 Real World

Adding initializers via extensions helps you add new ways to create objects without changing the original code. This is useful when working with libraries or when you want to keep your code organized.

💼 Career

Understanding how to extend existing types and add initializers is important for Swift developers working on apps that handle data parsing, user input, or need flexible object creation.

1

Create the Book struct

Create a struct called Book with two properties: title and author, both of type String.

Swift

// Your code here

Need a hint?

Use struct Book { var title: String; var author: String } to define the structure.

2

Add an extension with a new initializer

Add an extension to Book that defines a new initializer init(combined: String). Inside it, split the combined string by " - " and assign the first part to title and the second part to author.

Swift

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

// Your code here

Need a hint?

Use extension Book { init(combined: String) { ... } } and split(separator: "-") to separate the string.

3

Create a Book instance using the new initializer

Create a constant book using the new initializer with the string "1984 - George Orwell".

Swift

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

extension Book {
    init(combined: String) {
        let parts = combined.split(separator: "-").map { $0.trimmingCharacters(in: .whitespaces) }
        self.title = parts[0]
        self.author = parts[1]
    }
}

// Your code here

Need a hint?

Create the book with let book = Book(combined: "1984 - George Orwell").

4

Print the book's title and author

Print the title and author of the book constant using two separate print statements.

Swift

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

extension Book {
    init(combined: String) {
        let parts = combined.split(separator: "-").map { $0.trimmingCharacters(in: .whitespaces) }
        self.title = parts[0]
        self.author = parts[1]
    }
}

let book = Book(combined: "1984 - George Orwell")

// Your code here

Need a hint?

Use print(book.title) and print(book.author) to show the values.