In this chapter, we introduced the notion of a console interface and a GUI. We saw how to create Xcode playgrounds and went over the most important parts of the playground interface. We looked at the common first program every new developer will probably create, which is printing Hello World in the console, and how this can be implemented using Swift and a playground. We quickly looked at how Xcode playgrounds communicate errors in our program and how to interpret them. Lastly, we looked at how Xcode offers something called autocompletion to help us write code in a faster and safer manner.

In the next chapter, we will cover a fundamental concept in programming-the use of variables and constants. These are very handy as they, for example, help us reference our favorite ice cream without having to write the complete name of the ice cream everywhere in our program.