How to write a closure that returns a value

Swift version: 5.0

Paul Hudson    @twostraws    May 28th 2019

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

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