Initializers and designated init in Swift - Mini Project: Build & Apply

Initializers and Designated Init in Swift

📖 Scenario: You are creating a simple app to manage information about books in a library. Each book has a title and a number of pages.

🎯 Goal: Build a Swift struct called Book with a designated initializer that sets the title and pages. Then create an instance and print its details.

📋 What You'll Learn

Create a struct called Book with two properties: title (String) and pages (Int).

Add a designated initializer init(title: String, pages: Int) to set these properties.

Create a variable myBook using the initializer with title "Swift Programming" and pages 350.

Print the book's title and pages in the format: "Title: Swift Programming, Pages: 350".

💡 Why This Matters

🌍 Real World

Initializers help set up objects with the right starting values, just like filling out a form before using a new tool.

💼 Career

Understanding initializers is essential for building apps that manage data cleanly and safely, a key skill for Swift developers.

1

Create the Book struct with properties

Create a struct called Book with two properties: title of type String and pages of type Int.

Swift

struct Book {
    // Your code here
}

Need a hint?

Use struct keyword and declare two variables inside.

2

Add a designated initializer

Add a designated initializer init(title: String, pages: Int) inside the Book struct that sets the title and pages properties.

Swift

struct Book {
    var title: String
    var pages: Int

    // Your code here
}

Need a hint?

Use init with parameters and assign them to self properties.

3

Create an instance of Book

Create a variable called myBook and initialize it using Book(title: "Swift Programming", pages: 350).

Swift

struct Book {
    var title: String
    var pages: Int

    init(title: String, pages: Int) {
        self.title = title
        self.pages = pages
    }
}

// Your code here

Need a hint?

Use the initializer to create myBook with the exact title and pages.

4

Print the book details

Print the details of myBook in the format: "Title: Swift Programming, Pages: 350" using print and string interpolation.

Swift

struct Book {
    var title: String
    var pages: Int

    init(title: String, pages: Int) {
        self.title = title
        self.pages = pages
    }
}

var myBook = Book(title: "Swift Programming", pages: 350)

// Your code here

Need a hint?

Use print("Title: \(myBook.title), Pages: \(myBook.pages)") to show the output.