Swift Game Development - Third Edition

Swift, as a modern programming language, benefits from the collective experience of the programming community; it combines the best parts of other languages and avoids poor design decisions. Here are a few of my favorite Swift features:

I will try to make this text easy to understand for all skill levels:

By the end of this book, you will be capable of creating and publishing your own iOS games. You will know how to combine the techniques we will learn to create your own style of game and you will be well prepared to dive into more advanced topics with a solid foundation in 2D, 3D, and AR game design.

This year, we have the release of Swift version 4.2 with Xcode 10. Unlike previous years where we saw a full release of a Swift version, like Swift 3.0 and Swift 4.0, this year, we see the release of Version 4.2. Swift 5.0 has been moved to the sometime early next year in 2019.

Xcode 10 will be the last version to support Swift 3.0 Compatibility Mode. So, if your app uses Xcode version 3, the code needs to be migrated to at least 4.0 by next year.

Further refinements have also been introduced by Apple in Swift 4.2:

Swift has already made tremendous steps forward as a powerful, young language. Now, Apple is working on polishing Swift into a mature, production-ready tool. The overall developer experience improves with Swift 4.2.

With Swift 4.2, we are moving toward binary compatibility and with Swift 5.0 releasing in early 2019, this transition will be complete. With this, Apple will be able to ship the Swift runtime along with the OS itself and doesn't need to be included in the App bundle as it is currently. This will improve startup time and memory usage of the application itself. More information about binary compatibility/ abi-stability is available at swift.org/abi-stability.

Learning a new development environment can be a roadblock. Luckily, Apple provides some excellent tools for iOS developers. We will start our journey by installing Xcode.

Navigating our project

Now that we have created our project, you will see the project navigator on the left-hand side of Xcode. You will use the project navigator to add, remove, and rename files and generally organize your project. You might notice that Xcode has created quite a few files in our new project. We will take it slow; don't feel that you have to know what each file does yet, but feel free to explore them if you are curious:

Use the project navigator to open up the file named GameScene.swift. Xcode created GameScene.swift to store the default scene of our new game.

What is a scene? SpriteKit uses the concept of scenes to encapsulate each unique area of a game. Think of the scenes in a movie; we will create a scene for the main menu, a scene for the Game Over screen, a scene for each level in our game, and so on. If you are on the main menu of a game and you tap Play, you move from the menu scene to the Level 1 scene.

SpriteKit prepends its class names with the letters "SK"; consequently, the scene class is SKScene.

You will see that there is already some code in this scene. The SpriteKit project template comes with a very short demo. Let's take a quick look at this demo code and use it to test the iOS simulator.

Please do not be concerned with understanding the demo code at this point. Your focus should be on learning about the development environment.

Look for the run toolbar at the top of the Xcode window. It should look something like the following:

Select the iOS device of your choice to simulate using the dropdown on the far right. Which iOS device should you simulate? You are free to use the device of your choice. I will be using an iPhone X for the screenshots in this book, so choose iPhone X if you want your results to match my images perfectly.

Unfortunately, expect your game to play poorly in the simulator. SpriteKit suffers from poor FPS (Frames Per Second) in the iOS simulator. Once our game becomes relatively complex, we will see our FPS drop, even on high-end computers. The simulator will get you through, but it is best if you can plug in a physical device for testing.

It is time for our first glimpse of SpriteKit in action! Press the gray play arrow on the toolbar (handy keyboard shortcut: command + R). Xcode will build the project and launch the simulator. The simulator starts in a new window, so make sure you bring it to the front. You should see a gray background with white text: Hello, World. Click around on the gray background. You will see colorful, spinning boxes spawning wherever you click:

If you have made it this far, congratulations! You have successfully installed and configured everything you need to make your first Swift game.

Once you have finished playing with the spinning squares, you can close the simulator down and return to Xcode. Note that you can use the keyboard command command + Q to exit the simulator, or press the stop button inside Xcode. If you use the stop button, the simulator will remain open and launch your next build faster.

Let's quickly explore the demo code. Do not worry about understanding everything just yet; we will cover each element in depth later. At this point, I am hoping you will acclimatize to the development environment and pick up a few things along the way. If you are stuck, keep going! Things will actually get simpler in the next chapter, once we clear away the SpriteKit demo and start on our own game.

Make sure you have GameScene.swift open in Xcode.

The demo GameScene class implements some functions you will use in your games. Let's examine these functions. Feel free to read the code inside each function, but I do not expect you to understand the specific code just yet:

I hope that you have absorbed some Swift syntax and gained an overview of Swift and SpriteKit. It is time to make room for our own game; let's clear all of that demo code out! We want to keep a little bit of the boilerplate, but we can delete most of what is inside the functions. To be clear, I do not expect you to understand this code yet. This is simply a necessary step toward the start of our journey.

Firstly, we will remove the Hello, World text from the demo. Open the GameScene.sks file from the project navigator in Xcode. You will see a gray layout view with Hello, World written in the middle. Simply click anywhere on the Hello, World text and press your Delete key to remove it. Make sure you save your file before moving on.

Secondly, please replace all of the code from your GameScene.swift file with the following code:

import SpriteKit

class GameScene: SKScene { 
    override func didMove(to view: SKView) { 
    } 
} 

Once your GameScene.swift file looks like the preceding code, you are ready to move on to Chapter 2, Sprites, Camera, Actions! The real fun begins now!

You have already accomplished a lot. You have had your first experience with Swift, installed and configured your development environment, launched code successfully into the iOS simulator, and prepared your project for the first steps toward your own game. Great work!

We have seen enough of the "Hello World" demo; are you ready to draw your own graphics to the game screen? We will make use of sprites, textures, colors, and animation in Chapter 2, Sprites, Camera, Action!