For-in with where clause in Swift - Mini Project: Build & Apply

Filtering User Ages with For-in and Where Clause

📖 Scenario: You are managing a simple database of users and their ages. You want to find users who are adults (18 years or older) to send them a special offer.

🎯 Goal: Build a Swift program that uses a for-in loop with a where clause to filter and collect users who are 18 or older.

📋 What You'll Learn

Create a dictionary called users with these exact entries: "Alice": 17, "Bob": 20, "Charlie": 16, "Diana": 22

Create an empty array of strings called adultUsers to store names of adult users

Use a for-in loop with a where clause to iterate over users and select only those with age 18 or older

Inside the loop, append the user's name to adultUsers

💡 Why This Matters

🌍 Real World

Filtering data based on conditions is common in databases and apps, like selecting users eligible for offers.

💼 Career

Understanding loops with conditions helps in writing efficient queries and data processing code in many programming jobs.

1

Create the users dictionary

Create a dictionary called users with these exact entries: "Alice": 17, "Bob": 20, "Charlie": 16, "Diana": 22

Swift

# Create the users dictionary with exact entries
# Your code here

Need a hint?

Use square brackets [] to create the dictionary and separate entries with commas.

2

Create the adultUsers array

Create an empty array of strings called adultUsers to store names of adult users

Swift

let users = ["Alice": 17, "Bob": 20, "Charlie": 16, "Diana": 22]
# Create an empty array called adultUsers
# Your code here

Need a hint?

Use var to create a mutable array and specify the type as [String].

3

Use for-in loop with where clause

Use a for-in loop with a where clause to iterate over users and select only those with age 18 or older. Use for (name, age) in users where age >= 18

Swift

let users = ["Alice": 17, "Bob": 20, "Charlie": 16, "Diana": 22]
var adultUsers: [String] = []
# Use a for-in loop with where clause to filter adults
# Your code here

Need a hint?

The where clause filters the loop to only run for users 18 or older.

4

Complete the filtering logic

Ensure the for-in loop with where clause appends the user's name to adultUsers inside the loop body

Swift

let users = ["Alice": 17, "Bob": 20, "Charlie": 16, "Diana": 22]
var adultUsers: [String] = []
for (name, age) in users where age >= 18 {
    # Append the name to adultUsers
    # Your code here
}

Need a hint?

Use the append method on adultUsers to add the name inside the loop.