Ball with the new Sprite kit

Question

I\'m trying to make a simple forever bouncing ball with new sprite kit on ios 7. I set gravity:

 scene.physicsWorld.gravity=CGVectorMake(0, -9);

Answer 1

it's strange but if i set:

 ball.physicsBody.linearDamping=0.02f;

It seems that ball don't change its bounce height.