Lazy collections for performance in Swift - Mini Project: Build & Apply

Lazy collections for performance

📖 Scenario: Imagine you have a long list of numbers representing daily sales in a store. You want to find all sales that are bigger than 50 but you want to do it efficiently without checking every number immediately.

🎯 Goal: You will create a list of sales, then use a lazy collection to filter sales greater than 50. Finally, you will print the filtered sales. This shows how lazy collections help improve performance by delaying work until needed.

📋 What You'll Learn

Create an array called sales with these exact values: [10, 55, 30, 75, 20, 90]

Create a lazy collection called lazySales from the sales array

Use lazySales to filter sales greater than 50 and store in filteredSales

Print filteredSales converted to an array

💡 Why This Matters

🌍 Real World

Lazy collections are useful when working with large data sets where you want to avoid doing all the work upfront. For example, filtering or transforming big lists of sales, logs, or sensor data only when needed.

💼 Career

Understanding lazy collections helps you write efficient Swift code that performs better in apps, especially when handling large or complex data. This skill is valuable for iOS developers and software engineers working on performance-critical applications.

1

Create the sales data array

Create an array called sales with these exact values: [10, 55, 30, 75, 20, 90]

Swift

# Create the sales array with the exact values
# Your code here

Need a hint?

Use let sales = [10, 55, 30, 75, 20, 90] to create the array.

2

Create a lazy collection from sales

Create a lazy collection called lazySales from the sales array using the lazy property

Swift

let sales = [10, 55, 30, 75, 20, 90]
# Create lazySales as a lazy collection from sales
# Your code here

Need a hint?

Use let lazySales = sales.lazy to create the lazy collection.

3

Filter sales greater than 50 using lazy collection

Use lazySales to filter sales greater than 50 and store the result in filteredSales

Swift

let sales = [10, 55, 30, 75, 20, 90]
let lazySales = sales.lazy
# Filter lazySales for values greater than 50 and assign to filteredSales
# Your code here

Need a hint?

Use lazySales.filter { $0 > 50 } to filter values greater than 50.

4

Print the filtered sales as an array

Print filteredSales converted to an array using Array(filteredSales)

Swift

let sales = [10, 55, 30, 75, 20, 90]
let lazySales = sales.lazy
let filteredSales = lazySales.filter { $0 > 50 }
# Print filteredSales as an array
# Your code here

Need a hint?

Use print(Array(filteredSales)) to show the filtered results.