If you are reading this book, you are probably very familiar with Swift's built-in data types and data structures. However, to really unleash their power, we need to understand how they are implemented in the Swift standard library.
The Swift standard library defines several standard data types, such as Int, Double, and String. In most languages, these types are implemented as primitive types, which means that they cannot be extended or subclassed. In Swift, however, these types are implemented in the Swift standard library as structures, which means we can extend these types just as we can with any other type that is implemented as a structure; however, we cannot subclasses them as we can do with other languages.
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You can read more about Swift's standard library at http://swiftdoc.org.
Swift also defines several standard data structures, such as arrays, dictionaries, and sets. Just like the built-in data types, these are also implemented as structures in the Swift...