How to write a closure that returns a value

Paul Hudson    February 13th 2018    @twostraws

Like regular functions, closures can accept values and return values of your choosing: just write them out at the start of your closure, followed by the word in.

For example, we could write a greeting closure that accepts the name of a person to greet and returns a string using that name:

let greeting = { (name: String) -> String in
    return "Hello, \(name)!"
}

You can now call that just like any other function, passing in someone’s name as its only parameter:

let message = greeting("Taylor")

Available from iOS 8.0

Did this solution work for you? Please pass it on!

Tweet

Other people are reading…

• How to find the difference between two arrays
• How to check your program state using precondition()
• What's the difference between let and var?
• What is a monad?
• How to loop over non-nil items in an array

About the Swift Knowledge Base

This is part of the Swift Knowledge Base, a free, searchable collection of solutions for common iOS questions.