Argument labels and parameter names in Swift - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the difference between an argument label and a parameter name in Swift?

An argument label is used when calling a function to clarify the meaning of each argument. A parameter name is used inside the function to refer to the passed value.

beginner

How do you define a function in Swift with different argument labels and parameter names?

Use the syntax func functionName(argumentLabel parameterName: Type). For example: <br>func greet(person name: String) { print("Hello, \(name)!") } where person is the argument label and name is the parameter name.

intermediate

What happens if you use an underscore (_) as an argument label in Swift?

Using an underscore _ as the argument label means you don’t have to write the label when calling the function. It makes the argument label invisible to the caller.

beginner

Why are argument labels useful in Swift functions?

Argument labels make function calls more readable and clear, like giving names to the values you pass. They help others understand what each argument means without looking inside the function.

beginner

Show an example of a Swift function with no argument labels and explain how to call it.

Example: <br>func add(_ a: Int, _ b: Int) -> Int { return a + b }<br>You call it without labels: add(3, 5). The underscores mean no labels are needed when calling.

In Swift, what is the purpose of an argument label?

A To clarify the meaning of an argument when calling a function

B To name the parameter inside the function

C To declare the return type of a function

D To define a variable inside the function

Argument labels are used when calling a function to make the meaning of each argument clear.

How do you make a Swift function argument label invisible when calling the function?

A Use the keyword 'invisible'

B Use an underscore '_' as the argument label

C Omit the parameter name

D Use the keyword 'hidden'

Using '_' as the argument label hides it when calling the function.

Given the function: func greet(person name: String), how do you call it?

A greet("Anna")

B greet(name: "Anna")

C greet(person: "Anna")

D greet(person name: "Anna")

You use the argument label 'person' when calling: greet(person: "Anna")

What is the parameter name used for in Swift functions?

A To label arguments when calling the function

B To define the function name

C To specify the return type

D To refer to the argument value inside the function

Parameter names are used inside the function to refer to the passed values.

Which of the following is a correct way to define a function with different argument label and parameter name?

A func sum(first a: Int, second b: Int) {}

B func sum(a b: Int, c d: Int) {}

C func sum(a: Int, b: Int) {}

D func sum(_ a: Int, _ b: Int) {}

Option A uses different argument labels ('first', 'second') and parameter names ('a', 'b').

Explain the difference between argument labels and parameter names in Swift and why they are useful.

Think about how you call a function versus how you use values inside it.

Write a Swift function that uses argument labels different from parameter names and show how to call it.

Use the syntax: func name(argumentLabel parameterName: Type)