Swift is Apple's entirely new multi-paradigm programming language for developing applications on Apple devices. Swift has been in development for 4 years, and was announced in 2014 at the Worldwide Developer Conference (WWDC). Swift is both, a scripting and programming language; it has the ability to return multiple return values. Swift takes different constructs that are loved from many languages including Objective-C, Rust, Haskell, Ruby, Python, C#, CLU, and more. It has type safety feature that is, to prevent you passing string as int thus minimizing possible errors in your code.

We will be discussing more about Swift, as and when required, in the further topics covered.

Sprite Kit is a framework from Apple, meant for developing 2D games for iOS devices. It is one of the best ways to make games for iOS devices. It is easy to learn, powerful and fully supported by Apple, which makes it more reliable to use than third-party game development engines.

Sprite Kit was introduced in iOS 7 and allowed easy, fast game development; it has similarities with Cocos2d, which is a popular library for game development. If you are somewhat familiar with Cocos2d, Sprite Kit will be a breeze for you.

Sprite Kit provides various functionalities that are useful for games, such as graphics rendering, animation utilities, sound playback, a particle system, and physics simulation. In Sprite Kit, every node will have a property name and physics body, which can consist of arbitrary shapes such as rectangles, polygons, circles, paths, and so on. Sprite Kit provides a richer particle system, where any aspect can be changed by code during the animation. In Sprite Kit's particle system, you can also add custom actions to the particles created. In addition, Xcode provides built-in support for Sprite Kit so that you can create complex special effects and texture atlases directly in Xcode. This combination of framework and tools makes Sprite Kit a good choice for games and other apps that require similar kinds of animation.

Because Sprite Kit supports a rich rendering infrastructure, and handles all of the low-level work to submit drawing commands to OpenGL, you can focus your efforts on solving higher-level design problems and creating your game functionality.

As Sprite Kit is a native framework of iOS, it provides in-built support for using the particle effects, texture effects, and physics simulations. The performance of Sprite Kit is better than other third-party frameworks/gaming engines, as it is a native framework.

The main advantage of Sprite Kit is that it's built into iOS. There is no need to download any other third-party libraries or depend on external resources to develop 2D games. Other iOS APIs such as, iAd, In-App purchases, and so on, can be easily used without banking on extra plugins. You don't have to get familiar with any new programming language, the languages supported for Sprite Kit can also be used for app development on iOS. The best thing of all is that it is free, you get all the functionalities of Sprite Kit at no cost. You can run your game on both Mac and iOS without much effort, all you need to do is change its controls.

Now we are going to discuss some elements of Sprite Kit, which are essential for game development. A game made in Sprite Kit consists of many scenes which are made of nodes, and the functioning of a node in a scene is determined by actions.

Sprite Kit provides many features to facilitate the development of a game. These features can be used for enhancing the experience as well as performance of the game. Let's discuss them in brief.

The game loop

Following is a frame life cycle diagram:

At the start, the update function is called to where we set up the logic of the game. After that, the scene evaluates the actions. After the actions are evaluated, we get a callback. After that, we set up physics, if any. When the physics simulation is finished, we get another call with didSimulatePhysics. Then, we apply constraint and get another callback, didApplyConstraints. The last callback method is didFinishUpdate; we get it just before frame is completed and view is ready to render. Finally SKView renders the scene; the frame is complete and it continues 60 times per second.

We have discussed many things about Sprite Kit, now it's time to see a project in action and gain some practical knowledge.

Run the default game project by pressing ⌘ + R on your keyboard, or by clicking on the little play button in the top left corner. If a simulator isn't present, Xcode will download one for you before launching the app. The result will look as follows:

We also learned how to create a Sprite Kit project and run Hello World in it.

In the next chapter, we will be diving deeply into scenes, and also into adding scenes to our Platformer game.