Playgrounds is a powerful tool for trying out code and getting the result. As its name suggests, it's a place to play. In a playground, Swift code is evaluated immediately, which is the same as in REPL. You can create a new playground by going to File | New | Playground. Enter the file name and create it.
A playground consists of two parts, which are shown in the next screenshot:
Almost all the code examples shown in this book were created in playgrounds. As an example, let's create an array and play with it. We can apply filter and map functions and print the count of objects in an array:
You will see the result of the evaluated ...