Omitting argument labels with _ in Swift - Mini Project: Build & Apply

Using _ to Omit Argument Labels in Swift Functions

📖 Scenario: Imagine you are creating a simple calculator app that adds two numbers. You want to make the function call easy and clean by omitting argument labels.

🎯 Goal: Build a Swift function that adds two numbers without requiring argument labels when calling it.

📋 What You'll Learn

Create a function named add that takes two Int parameters without argument labels.

Use _ to omit argument labels in the function definition.

Call the function with two numbers without labels.

Print the result of the addition.

💡 Why This Matters

🌍 Real World

Omitting argument labels makes function calls simpler and more natural, especially in small utility functions or when the meaning is clear from context.

💼 Career

Swift developers often use <code>_</code> to improve code readability and API design in iOS app development.

1

Create the add function with two parameters

Write a function named add that takes two Int parameters named a and b. For now, just return 0 inside the function.

Swift

# Write the function named add with parameters a and b
# Your code here

Need a hint?

Define the function with func add(a: Int, b: Int) -> Int and return 0 for now.

2

Omit argument labels using _

Modify the add function so that both parameters a and b omit argument labels by using _ before their names.

Swift

func add(_ a: Int, _ b: Int) -> Int {
    return 0
}
# Your code here

Need a hint?

Use _ before each parameter name like func add(_ a: Int, _ b: Int) -> Int.

3

Implement addition logic inside the function

Change the add function to return the sum of a and b.

Swift

func add(_ a: Int, _ b: Int) -> Int {
    // Return the sum of a and b
    # Your code here
}

Need a hint?

Return a + b inside the function.

4

Call the function without argument labels and print the result

Call the add function with arguments 5 and 7 without labels, store the result in sum, and print sum.

Swift

let sum = add(5, 7)
// Print the sum
# Your code here

Need a hint?

Call add(5, 7), assign to sum, then print sum.