Shorthand argument names ($0, $1) in Swift - Mini Project: Build & Apply

Using Shorthand Argument Names ($0, $1) in Swift

📖 Scenario: Imagine you are organizing a small party and you have a list of guests with their ages. You want to create a new list that shows only the guests who are adults (18 years or older).

🎯 Goal: You will learn how to use shorthand argument names $0 and $1 in Swift closures to filter and sort the guest list easily.

📋 What You'll Learn

Create a dictionary called guests with the exact entries: "Anna": 22, "Ben": 17, "Cara": 19, "David": 15, "Eva": 20

Create a variable called ageLimit and set it to 18

Use the filter method with a closure using shorthand argument name $0 to keep guests who are 18 or older

Use the sorted method with a closure using shorthand argument names $0 and $1 to sort guests by their names alphabetically

Print the filtered and sorted list of guests

💡 Why This Matters

🌍 Real World

Filtering and sorting data is common when managing lists like guest lists, contacts, or products.

💼 Career

Understanding shorthand argument names helps write concise and readable Swift code, useful for iOS app development.

1

Create the guest list dictionary

Create a dictionary called guests with these exact entries: "Anna": 22, "Ben": 17, "Cara": 19, "David": 15, "Eva": 20

Swift

# Create the dictionary called guests with the given entries
# Your code here

Need a hint?

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

2

Set the age limit variable

Create a variable called ageLimit and set it to 18

Swift

let guests = ["Anna": 22, "Ben": 17, "Cara": 19, "David": 15, "Eva": 20]
# Create the variable ageLimit and set it to 18
# Your code here

Need a hint?

Use let to create a constant variable.

3

Filter guests who are adults using shorthand argument name

Use the filter method on guests with a closure using the shorthand argument name $0 to keep only guests whose age is greater than or equal to ageLimit. Store the result in a variable called adultGuests.

Swift

let guests = ["Anna": 22, "Ben": 17, "Cara": 19, "David": 15, "Eva": 20]
let ageLimit = 18
# Filter guests to keep only adults using $0
# Your code here

Need a hint?

Inside the closure, $0 represents each key-value pair (a tuple). Use $0.value to access the age.

4

Sort and print the adult guests

Use the sorted method on adultGuests with a closure using shorthand argument names $0 and $1 to sort guests by their names alphabetically. Then print the sorted list.

Swift

let guests = ["Anna": 22, "Ben": 17, "Cara": 19, "David": 15, "Eva": 20]
let ageLimit = 18
let adultGuests = guests.filter { $0.value >= ageLimit }
# Sort adultGuests by name using $0 and $1 and print the result
# Your code here

Need a hint?

Use $0.key and $1.key to compare guest names inside the closure.