Make edges of SKSpriteNode look smooth after rotation

Question

I create a SKSpriteNode like that:

var shape:SKSpriteNode = SKSpriteNode(color: UIColor.redColor(), size: CGSizeMake(CGFloat(sizeOfShape), CGFloat(sizeOfShape)))

How can I achieve, that a SKSpriteNode has still smooth edges, after I've rotated it.

Currently, it looks like that:

As you see, the edges are jagged.