Up to this point, we have been laying the foundation for writing applications with Swift. While it is possible to write a very basic application with what we have learned so far, it would be really difficult to write a useful application using only what we covered in the first three chapters.

Starting with this chapter, we will begin to move away from the foundations of the Swift language, and begin to learn the building blocks of application development with Swift. In this chapter, we will go over control flow and functions. To become a master of the Swift programming language, it is important that you fully understand and comprehend the concepts discussed in this chapter and in Chapter 5, Classes and Structures.

Before we cover control flow and functions, let's take a look at how curly brackets and parentheses are used in Swift.