Variadic functions

Some functions are variadic, which is a fancy way of saying they accept any number of parameters of the same type. The print() function is actually variadic: if you pass lots of parameters, they are all printed on one line with spaces between them:

print("Haters", "gonna", "hate")

You can make any parameter variadic by writing ... after its type. So, an Int parameter is a single integer, whereas Int... is zero or more integers – potentially hundreds.

Inside the function, Swift converts the values that were passed in to an array of integers, so you can loop over them as needed.

To try this out, let’s write a square() function that can square many numbers:

func square(numbers: Int...) {
    for number in numbers {
        print("\(number) squared is \(number * number)")
    }
}

Now we can run that with lots of numbers just by passing them in separated by commas:

square(numbers: 1, 2, 3, 4, 5)

SPONSORED Would you describe yourself as knowledgeable, but struggling when you have to come up with your own code? Fernando Olivares has a new book containing iOS rules you can immediately apply to your coding habits to see dramatic improvements, while also teaching applied programming fundamentals seen in refactored code from published apps.

Try the book!

Sponsor Hacking with Swift and reach the world's largest Swift community!