SKSpriteNodes移动方向

Question

如果我的SKSpriteNodes使用此代码从右向左移动

CGFloat distanceToMove = self.frame.size.width + 2 * _pipeTexture1.size.width;
SKAction* movePipes = [SKAction moveByX:-distanceToMove y:0 duration:0.01 * distanceToMove];
SKAction* removePipes = [SKAction removeFromParent];
_movePipesAndRemove = [SKAction sequence:@[movePipes, removePipes]];

问题是如何使这些SKSpriteNodes从上到下移动，我必须使用什么。谢谢