ReadLine Input

Part of the Fundamentals section of Coddy's Swift journey — lesson 33 of 86.

So far, your programs have used hardcoded values. To make programs interactive, you need to accept input from the user. In Swift, the readLine() function reads a line of text from standard input.

let input = readLine()
print(input)

There's an important detail here: readLine() returns an optional String (String?), not a regular String. This is because the input might be empty or unavailable. You'll need to unwrap it safely before using the value:

if let name = readLine() {
    print("Hello, \(name)!")
}

Using if let ensures you only work with the input when it actually contains a value. This pattern of reading input and safely unwrapping it is something you'll use frequently when building interactive programs.

Challenge

Easy

Write a function greetUser that takes name and returns a personalized greeting message.

The function simulates what you would do after safely unwrapping input from readLine(). Given a name, construct and return a greeting string.

Parameters:

name (String): The user's name

Returns: A greeting in the format: Hello, [name]!

Cheat sheet

To read user input in Swift, use the readLine() function:

let input = readLine()

readLine() returns an optional String (String?) because the input might be empty or unavailable. Use if let to safely unwrap the optional before using the value:

if let name = readLine() {
    print("Hello, \(name)!")
}

Try it yourself

func greetUser(name: String) -> String {
    // Write code here
}

Test yourself

This lesson includes a short quiz. Start the lesson to answer it and track your progress.

All lessons in Fundamentals

1Introduction

The Language Hello World!Comments

4Operators Part 1

Arithmetic Operators Modulo Operator Compound Assignment Recap - Simple Math Comparison Operators

7Basic IO

Print Function String InterpolationReadLine InputType Conversion Recap - Till 120 Recap - True or False

10Functions

Declare A Function Parameters And Arguments Return Values Argument Labels Recap - Sigma Function Recap - Validation Function Default Values

13Iterating Over Sequences

Iterating Over Elements The Enumerated Method Iterating Over Strings P1 Iterating Over Strings P2

16Final Challenges

Flat Asterisk Pyramid Pattern Finder What To Buy

2Variables

Let vs Var Type Annotations Numbers String Boolean Naming Conventions Recap - Initialize Variables

5Operators Part 2

Logical Operators Part 1 Logical Operators Part 2 Recap - Simple Logic Logical Operators Part 3 Ternary Operator

8Bill Split Calculator

Welcome Message Getting Input

Calculating Tip And Total

Splitting The Bill

Formatted Output

11FizzBuzz with a Twist

Game Overview The FizzBuzz Function

Looping The Numbers

Adding The Twist

14Arrays Advanced

Array Slicing Part 1 Array Slicing Part 2 Sequence Operators The Contains Method