O'Reilly logo

Mastering Swift 4 - Fourth Edition by Jon Hoffman

Stay ahead with the world's most comprehensive technology and business learning platform.

With Safari, you learn the way you learn best. Get unlimited access to videos, live online training, learning paths, books, tutorials, and more.

Start Free Trial

No credit card required

Simple closures

We will begin by creating a very simple closure that does not accept any arguments and does not return any value. All it does is print Hello World to the console. Let's look at the following code:

let clos1 = { () -> Void in  print("Hello World") 
} 

In this example, we create a closure and assign it to the constant clos1. Since there are no parameters defined between the parentheses, this closure will not accept any parameters. Also, the return type is defined as Void; therefore, this closure will not return any value. The body of the closure contains one line, which prints Hello World to the console.

There are many ways to use closures; in this example, all we want to do is execute it. We can execute the closure as follows: ...

With Safari, you learn the way you learn best. Get unlimited access to videos, live online training, learning paths, books, interactive tutorials, and more.

Start Free Trial

No credit card required