For-in loop with collections in Swift - Mini Project: Build & Apply

For-in Loop with Collections in Swift

📖 Scenario: You work at a small bookstore. You have a list of book titles and their prices. You want to find out which books cost more than $20.

🎯 Goal: Build a Swift program that uses a for-in loop to check each book's price and collect the titles of books costing more than $20.

📋 What You'll Learn

Create a dictionary called books with these exact entries: "Swift Programming": 25, "iOS Development": 18, "Data Structures": 30, "Algorithms": 15

Create a variable called priceThreshold and set it to 20

Use a for-in loop with variables title and price to iterate over books

Inside the loop, check if price is greater than priceThreshold and if so, add title to a list called expensiveBooks

Print the expensiveBooks list at the end

💡 Why This Matters

🌍 Real World

This project shows how to filter items from a collection based on conditions, a common task in apps like shopping, inventory, or data analysis.

💼 Career

Understanding how to loop through collections and apply conditions is essential for software developers working with data structures and user data.

1

Create the books dictionary

Create a dictionary called books with these exact entries: "Swift Programming": 25, "iOS Development": 18, "Data Structures": 30, "Algorithms": 15

Swift

# Create the books dictionary with the given entries
# Your code here

Need a hint?

Use square brackets [] to create a dictionary with key-value pairs separated by colons.

2

Set the price threshold

Create a variable called priceThreshold and set it to 20

Swift

let books = ["Swift Programming": 25, "iOS Development": 18, "Data Structures": 30, "Algorithms": 15]
# Create a variable called priceThreshold and set it to 20
# Your code here

Need a hint?

Use let to create a constant variable with the value 20.

3

Use a for-in loop to find expensive books

Create an empty array called expensiveBooks of type [String]. Then use a for-in loop with variables title and price to iterate over books. Inside the loop, check if price is greater than priceThreshold. If yes, append title to expensiveBooks.

Swift

let books = ["Swift Programming": 25, "iOS Development": 18, "Data Structures": 30, "Algorithms": 15]
let priceThreshold = 20
// Create an empty array called expensiveBooks
// Use a for-in loop to check prices and add titles to expensiveBooks
# Your code here

Need a hint?

Use for (title, price) in books to loop through the dictionary. Use append() to add items to the array.

4

Print the list of expensive books

Write a print statement to display the expensiveBooks array.

Swift

let books = ["Swift Programming": 25, "iOS Development": 18, "Data Structures": 30, "Algorithms": 15]
let priceThreshold = 20
var expensiveBooks: [String] = []
for (title, price) in books {
    if price > priceThreshold {
        expensiveBooks.append(title)
    }
}
# Print the expensiveBooks array
# Your code here

Need a hint?

Use print(expensiveBooks) to show the list of books costing more than $20.