title: use of undeclared identifier 'SKSpriteNode'
body: <p>I'm trying to define an SKSprite Node <code>SKSpriteNode *ball</code> but I'm getting this message "use of undeclared identifier 'SKSpriteNode'"</p>
  
  <p>I'm building my game with the help of SpriteBuilder Cocos2d and chipmunk physics using objective-C, my deployment target is IOS6 i tried to pot it to IOS7 but still the problem didn't get solved.</p>
  
  <p>In my interface i included <code>CCPhysicsCollisionDelegate</code>. I can use and define CCSprite and CCPhysicsNode without any problems.</p>
  
  <p>I'm trying to detect collisions using <code>collisionBitMask</code></p>
  
  <p>I read SKSpriteNode Class reference but didn't find anything useful for my problem or maybe i just didn't understand will
  <a href="https://developer.apple.com/library/ios/documentation/SpriteKit/Reference/SKSpriteNode_Ref/Reference/Reference.html#//apple_ref/occ/cl/SKSpriteNode" rel="nofollow noreferrer">https://developer.apple.com/library/ios/documentation/SpriteKit/Reference/SKSpriteNode_Ref/Reference/Reference.html#//apple_ref/occ/cl/SKSpriteNode</a></p>
  
  <p>I captured the error that i get in Xcode "focus on the SKSpriteNode error" 
  <img src="https://i.stack.imgur.com/3oJjI.png" alt="Capture from Xcode"></p>
  
  <p>Any help or hint would be appreciated ..</p>