SpriteKit将SKShapeNode置于场景中心

Question

我想要在场景中心绘制一个椭圆

 let center = (view.scene.position.x, view.scene.position.y)
 let size = (view.scene.frame.size.width * 0.7, view.scene.frame.size.height * 0.7)
 let ellipse = SKShapeNode (ellipseInRect: CGRectMake(center.0, center.1, size.0, size.1))
 ellipse.strokeColor = UIColor.blackColor()
 ellipse.position = CGPointMake(center)
 self.addChild(ellipse)

但它出现在场景中：

如何将其置于场景的中心？

Answer 1

而不是使用

let ellipse = SKShapeNode (ellipseInRect: CGRectMake(center.0, center.1, size.0, size.1))

使用

let ellipse = SKShapeNode (ellipseOfSize: CGSizeMake(size.0, size.1))

围绕精灵的中心

let center = (CGRectGetMidX(view.scene.frame), CGRectGetMidY(view.scene.frame))