import SpriteKit

class GameScene: SKScene {
    // Player
    var player:SKSpriteNode = SKSpriteNode()
    // Number of aliens destroyed
    var aliensDestroyed = 0
    // Used to decide when to add new aliens
    var lastYieldTimeInterval:NSTimeInterval = NSTimeInterval()
    var lastUpdateTimerInterval:NSTimeInterval = NSTimeInterval()
    
    override func didMoveToView(view: SKView) {
        
    }
    
    init(size:CGSize){
        super.init(size: size)
        // Initialize the background with a black color
        self.backgroundColor = SKColor.blackColor()
    }
    
    override func touchesBegan(touches: NSSet, withEvent event: UIEvent) {
        
    }
   
    override func update(currentTime: CFTimeInterval) {
        /* Called before each frame is rendered */
    }
}

import SpriteKit

class GameScene: SKScene {
    // Player
    var player:SKSpriteNode = SKSpriteNode()
    // Number of aliens destroyed
    var aliensDestroyed = 0
    // Used to decide when to add new aliens
    var lastYieldTimeInterval:NSTimeInterval = NSTimeInterval()
    var lastUpdateTimerInterval:NSTimeInterval = NSTimeInterval()
    
    override func didMoveToView(view: SKView) {
        
    }
    
    init(size:CGSize){
        super.init(size: size)
    }
    
    override func touchesBegan(touches: NSSet, withEvent event: UIEvent) {
        
    }
   
    override func update(currentTime: CFTimeInterval) {
        /* Called before each frame is rendered */
    }
}

--- 
+++ 
@@ -15,6 +15,8 @@
     
     init(size:CGSize){
         super.init(size: size)
+        // Initialize the background with a black color
+        self.backgroundColor = SKColor.blackColor()
     }
     
     override func touchesBegan(touches: NSSet, withEvent event: UIEvent) {
Initialize the background with a black color
