Centering the camera on a sprite
Games often require that the camera follows the player sprite as it moves through space. We definitely want this camera behavior for Pierre, our penguin character, whom we will soon be adding to the game. Since SpriteKit does not come with built-in camera functionality, we will create our own structure to simulate the effect we want.
One way we could accomplish this is by keeping Pierre in one position and moving every other object past him. This is effective, yet semantically confusing, and can cause errors when you are positioning game objects.
Creating a new world
I prefer to create a world node and attach all of our game nodes to it (instead of directly to the scene). We can move Pierre forward through the world ...