Collection mutability tied to let/var in Swift - Mini Project: Build & Apply

Collection Mutability Tied to let/var in Swift

📖 Scenario: You are managing a simple contact list app where you store names of friends. You want to understand how using let and var affects your ability to change the list.

🎯 Goal: Build a Swift program that creates a collection of friend names, sets a mutability flag, modifies the collection accordingly, and finalizes the collection to see how let and var control mutability.

📋 What You'll Learn

Create an array of friend names using var or let as instructed

Add a Boolean variable to indicate if the collection is mutable

Use an if statement to add a new friend only if the collection is mutable

Finalize the collection declaration to reflect the mutability

💡 Why This Matters

🌍 Real World

Managing lists of items like contacts, tasks, or products where you need to control if the list can be changed or not.

💼 Career

Understanding mutability is crucial for writing safe and predictable Swift code, especially in app development where data integrity matters.

1

Create a mutable array of friend names

Create a variable called friends using var and assign it an array with these exact names: "Alice", "Bob", "Charlie".

Swift

# Create a variable called friends with the names "Alice", "Bob", and "Charlie"
# Your code here

Need a hint?

Use var friends = ["Alice", "Bob", "Charlie"] to create a mutable array.

2

Add a mutability flag

Create a constant Boolean variable called isMutable and set it to true.

Swift

var friends = ["Alice", "Bob", "Charlie"]
# Create a constant Boolean called isMutable and set it to true
# Your code here

Need a hint?

Use let isMutable = true to create a constant Boolean.

3

Add a new friend if mutable

Use an if statement to check if isMutable is true. Inside the block, append the name "Diana" to the friends array.

Swift

var friends = ["Alice", "Bob", "Charlie"]
let isMutable = true
# Use if isMutable to append "Diana" to friends
# Your code here

Need a hint?

Use if isMutable { friends.append("Diana") } to add a friend only if mutable.

4

Change collection to immutable and finalize

Change the declaration of friends from var to let to make the array immutable. Keep the rest of the code the same.

Swift

var friends = ["Alice", "Bob", "Charlie"]
let isMutable = true
if isMutable {
    friends.append("Diana")
}
# Change friends to let to make it immutable
# Your code here

Need a hint?

Change var to let to make the array immutable.