Functions in Swift

Swift Function

Swift Function is a logical piece of code which represents a behaviour or functionality. A function can take arguments and can return a value.

Define a Function

To define a function in Swift, use func keyword; followed by function name; followed by the set of parameters that this function can accept, in parenthesis; followed by return type of the function, if any; and then the body of the function enclosed in flower braces.

The syntax of a function in Swift is

func functionName(parameterName1: Type, parameterName2: Type) -> ReturnType {
    //function body
}

where parameters and return type are optional.

Examples

In the following example, we will define a function greet, with no parameters and no return type. This function does print a message. After defining the function, we call it using the function name greet.

main.swift

func greet() {
    print("Hello World")
}

greet()

Output

Now, let us modify greet(), such that is accepts a String for its parameter.

main.swift

func greet(name: String) {
    print("Hello \(name)")
}

greet(name: "Abc")

Output

Let us return the message from the function greet() and then print the returned String value.

main.swift

func greet(name: String) -> String {
    return "Hello \(name)"
}

let value = greet(name: "Abc")
print(value)

Output

Swift Functions Tutorials

The following tutorials cover some of the concepts or examples related to Swift Functions.

• Swift – Define a Function with Parameters
• Swift – Function that Accepts One or More Values for a Parameter
• Swift – Call Function with no Parameter Labels
• Swift – Custom Label for Function Parameter(s)
• Swift – Assign Default Value for Parameter(s) in Function
• Swift – Pass Parameter by Reference to Function
• Swift – Assign Function to a Variable
• Swift – Pass Function as Parameter
• Swift – Return a Function from another Function

Programs

• Swift – Find Sum of One or More Integers

Conclusion

In this Swift Tutorial, we learned about Functions in Swift programming.