title: Why orientating sprites doesn't work from ´didEndContact()´ but does from ´update()´
body: <p>I have the following code in my GameScene-class that orients all the moving sprites to the direction that they are going. It works perfectly if called from update() but I cannot understand why it doesn't work at all when called from didEndContact.</p>
  
  <p>The problem with being called from update() is that when scene transition begins, update is no longer called (it seems) and all sprite stop orientating them selves. I have long scene transitions so it looks bad.      </p>
  
  <pre><code>func updateSpriteDirections(){
  
      var i = 1
      var nodeToUpdate: SKSpriteNode?
      nodeToUpdate = self.childNodeWithName("sprite\(i)") as! SKSpriteNode!
      while (nodeToUpdate != nil){
          changeSpriteDirection(nodeToUpdate!)
          i += 1
          nodeToUpdate = self.childNodeWithName("sprite\(i)") as! SKSpriteNode!
  
      }
  
  
  func didEndContact(contact: SKPhysicsContact) {
          updateSpriteDirections()
  }
  override func update(currentTime: CFTimeInterval) {
      updateSpriteDirections()
  
  }
  func changeSpriteDirection(sprite: SKSpriteNode){
  
      let nodeToTurn = self.childNodeWithName(sprite.name!)
      if(nodeToTurn != nil) {
          let angle = atan2(sprite.physicsBody!.velocity.dy, sprite.physicsBody!.velocity.dx)
          nodeToTurn!.zRotation =  angle - 90 * DegreesToRadians
      }
  
  }
  </code></pre>