Variadic parameters in Swift - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a variadic parameter in Swift?

A variadic parameter allows a function to accept zero or more values of a specified type as input. It is written with three dots (...) after the parameter's type.

beginner

How do you declare a variadic parameter in a Swift function?

You add three dots (...) after the parameter type. For example: <br>func sum(numbers: Int...) means the function can take many Int values.

intermediate

Can a Swift function have more than one variadic parameter?

No, a function can have only one variadic parameter, and it must be the last parameter in the function's parameter list.

beginner

How do you access the values passed to a variadic parameter inside the function?

Inside the function, the variadic parameter is treated as an array of the specified type. You can loop over it or access elements by index.

beginner

Example: What does this Swift function do?<br>

func greet(names: String...) {<br>  for name in names {<br>    print("Hello, \(name)!")<br>  }<br>}

This function takes any number of names as input and prints a greeting for each one. For example, calling greet(names: "Anna", "Bob") prints:<br>Hello, Anna!<br>Hello, Bob!

How do you declare a variadic parameter in Swift?

A Add three dots (...) after the parameter type

B Use square brackets [] around the parameter

C Use an asterisk * before the parameter name

D Declare the parameter as optional with ?

Variadic parameters use three dots (...) after the type to accept multiple values.

How many variadic parameters can a Swift function have?

A Two, but only if they are of the same type

B Any number, anywhere in the parameter list

C Only one, and it must be last

D None, Swift does not support variadic parameters

Swift allows only one variadic parameter per function, and it must be the last parameter.

Inside a function, a variadic parameter is treated as:

A An array of the parameter's type

B A single value of the parameter's type

C A dictionary with keys as indexes

D A tuple of fixed size

Variadic parameters are accessible as arrays inside the function.

What happens if you call a function with a variadic parameter but pass no arguments for it?

A The function throws an error

B The variadic parameter is an empty array

C The function ignores the parameter

D The function uses a default value

If no arguments are passed, the variadic parameter is an empty array.

Which of these is a valid function declaration with a variadic parameter?

A func add(numbers: [Int]...)

B func add(...numbers: Int)

C func add(numbers: Int, others: Int...)

D func add(numbers: Int...)

The correct syntax places the three dots after the type and only one variadic parameter is allowed.

Explain what a variadic parameter is and how you use it in a Swift function.

Think about how you can pass many values to one parameter.

Describe the rules and limitations of using variadic parameters in Swift functions.

Consider function parameter order and count.