9.14 Closure Expressions

Having covered the basics of functions in Swift it is now time to look at the concept of closures and closure expressions. Although these terms are often used interchangeably there are some key differences.

Closure expressions are self-contained blocks of code. The following code, for example, declares a closure expression and assigns it to a constant named sayHello and then calls the function via the constant reference:

let sayHello = { print("Hello") }

sayHello()

Closure expressions may also be configured to accept parameters and return results. The syntax for this is as follows:

{(<para name>: <para type>, <para name> <para type>, ... ) ->

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