Function declaration syntax in Swift - Mini Project: Build & Apply

Function declaration syntax

📖 Scenario: Imagine you are creating a simple calculator app that can greet users and perform basic math operations.

🎯 Goal: You will learn how to declare functions in Swift to greet users and add two numbers.

📋 What You'll Learn

Declare a function called greetUser that prints a greeting message.

Declare a function called addNumbers that takes two Int parameters and returns their sum.

Call both functions to see their output.

💡 Why This Matters

🌍 Real World

Functions help organize code into reusable blocks, making apps easier to build and maintain.

💼 Career

Knowing how to declare and use functions is essential for any Swift developer working on iOS or macOS apps.

1

Create a simple function to greet the user

Declare a function called greetUser that prints the message "Hello, welcome to the calculator!".

Swift

# Declare the greetUser function that prints a welcome message
// Your code here

Need a hint?

Use the func keyword followed by the function name and parentheses. Inside curly braces, use print to show the message.

2

Add a function to sum two numbers

Declare a function called addNumbers that takes two Int parameters named a and b, and returns their sum as an Int.

Swift

func greetUser() {
    print("Hello, welcome to the calculator!")
}

// Declare addNumbers function that takes two Int parameters and returns an Int
// Your code here

Need a hint?

Remember to specify parameter types and the return type after an arrow ->. Use return to send back the sum.

3

Call the functions to see their output

Call the greetUser() function and then call addNumbers(a: 5, b: 7) storing the result in a variable called result.

Swift

func greetUser() {
    print("Hello, welcome to the calculator!")
}

func addNumbers(a: Int, b: Int) -> Int {
    return a + b
}

// Call greetUser and store the sum of 5 and 7 in result
// Your code here

Need a hint?

Call functions by writing their name followed by parentheses. Assign the returned value to a variable using let.

4

Print the result of the addition

Print the value stored in the variable result using print.

Swift

func greetUser() {
    print("Hello, welcome to the calculator!")
}

func addNumbers(a: Int, b: Int) -> Int {
    return a + b
}

greetUser()
let result = addNumbers(a: 5, b: 7)

// Print the result variable
// Your code here

Need a hint?

Use print(result) to show the sum on the screen.