To follow along with the examples in this book, you will need to have an Apple computer with OS X 10.14 or higher installed. You will also need to install Xcode version 10.2 or higher with Swift version 5 or higher. You should possess at least a basic knowledge of the Swift programming language and how to use the development tools on their environment.

You can download the example code files for this book from your account at www.packt.com. If you purchased this book elsewhere, you can visit www.packt.com/support and register to have the files emailed directly to you.

You can download the code files by following these steps:

1. Log in or register at www.packt.com.
2. Select the SUPPORT tab.
3. Click on Code Downloads & Errata.
4. Enter the name of the book in the Search box and follow the onscreen instructions.

Once the file is downloaded, please make sure that you unzip or extract the folder using the latest version of:

• WinRAR/7-Zip for Windows
• Zipeg/iZip/UnRarX for Mac
• 7-Zip/PeaZip for Linux

The code bundle for the book is also hosted on GitHub at https://github.com/PacktPublishing/Swift-5-Protocol-Oriented-Programming-Fourth-Edition. In case there's an update to the code, it will be updated on the existing GitHub repository.

We also have other code bundles from our rich catalog of books and videos available at https://github.com/PacktPublishing/. Check them out!

There are a number of text conventions used throughout this book.

CodeInText: Indicates code words in text, database table names, folder names, filenames, file extensions, pathnames, dummy URLs, user input, and Twitter handles. Here is an example: "To define the protocol, we use the protocol keyword, followed by the name of the protocol."

A block of code is set as follows:

struct  MyStruct:  MyProtocol  { 
    //Structure  implementation  here 
}

When we wish to draw your attention to a particular part of a code block, the relevant lines or items are set in bold:

Initializing class with name One
Initializing class with name Two
Setting class1ref1 to nil
Releaseing class with name One
Setting class2ref1 to nil
Setting class2ref2 to nil
Releaseing class with name Two

Bold: Indicates a new term, an important word, or words that you see onscreen. For example, words in menus or dialog boxes appear in the text like this. Here is an example: "If we run this example, we will see that the Notification Received message."