Sprite Kit Best Practices - Beginning Swift Games Development for iOS - page 140

}
The addOrbsToForeground() method is now much simpler. It performs only three
steps. It creates each of the orb nodes, sets their respective positions, and then adds them
to the scene.
The last node class you are going to create is the BlackHole class. As you can probably
guess, this class will contain all the code related to a black hole. Create another new file
named BlackHole.swift and copy the contents of Listing 9-4 into it.
Listing 9-4 . BlackHole.swift: The New BlackHole Class
import Foundation
import SpriteKit
class BlackHole: SKSpriteNode {
override init() {
let textureAtlas = SKTextureAtlas(named:
"sprites.atlas")
var frame0 = textureAtlas.textureNamed("BlackHole0")
var frame1 = textureAtlas.textureNamed("BlackHole1")
var frame2 = textureAtlas.textureNamed("BlackHole2")
var frame3 = textureAtlas.textureNamed("BlackHole3")
var frame4 = textureAtlas.textureNamed("BlackHole4")
var blackHoleTextures = [frame0, frame1, frame2,
frame3, frame4]
var animateAction =
SKAction.animateWithTextures(blackHoleTextures,
timePerFrame: 0.2)
var rotateAction
= SKAction.repeatActionForever(animateAction)
super.init(texture: frame0,
color: UIColor.clearColor(),
size: frame0.size())
physicsBody = SKPhysicsBody(circleOfRadius:
size.width / 2)
physicsBody!.dynamic = false
physicsBody!.categoryBitMask
= CollisionCategoryBlackHoles
physicsBody!.collisionBitMask = 0