Now the bird is flapping, but there are no enemies, so the game is pretty boring. It's time to add some obstacles—pipes!
To implement the pipes as they were in the original game, we need two classes: PipesNode, which contains the top and bottom pipes; and Pipes, which creates and handles PipesNode.
Let's begin with Pipes and add it as an actor to GameScene:
//...
let pipes = Pipes(topPipeTexture: "topPipe.png", bottomPipeTexture: "bottomPipe").addTo(screenNode)
actors = [sky, city, ground, bird, pipes]
//...The Pipes class holds the texture name, and it is added to the nodes tree:
import SpriteKit
class Pipes {
private class var createActionKey : String { get {return "createActionKey"} }
private var parentNode: SKSpriteNode!
private let topPipeTexture: String
private let bottomPipeTexture: String
init(topPipeTexture: String, bottomPipeTexture: String) {
self.topPipeTexture = topPipeTexture
...