Function that accepts One/More Values for a Parameter in Swift

Swift Function – Accept One or More Values for a Parameter

To define a function that can accept one or more values for a parameter, also called a variadic parameter, declare the parameter followed by three period characters ... after the type.

The syntax to define a function with parameter that can accept one or more values is

func functionName(_ variableName: <T>...) {
    //body
}

Please observe the underscore _ followed by a space before parameter declaration, and the three dots ... after the type in parameter declaration.

Example

In the following example, we will define a function that can accept one or more int values via numbers parameter and find the sum of these values.

main.swift

func sum(_ numbers: Int...) {
    var result = 0
    for n in numbers {
        result += n
    }
    print("The sum of numbers is \(result)")
}

sum(2, 3)
sum(1, 2, 8, 4, 6)

Output

In the first function call, sum(2, 3), we passed only two values for the parameter numbers.

In the second function call, sum(1, 2, 8, 4, 6), we passed five values for the parameter numbers.

We can also not pass any value for the variadic parameter.

main.swift

func sum(_ numbers: Int...) {
    var result = 0
    for n in numbers {
        result += n
    }
    print("The sum of numbers is \(result)")
}

sum()

Output

Conclusion

In this Swift Tutorial, we learned how to define a function in Swift with with a variadic parameter that can accept one or more values.