Swift：每次触摸屏幕时如何更改背景的位置？

Question

我希望每次触摸屏幕时我的背景节点向下移动50个像素。

编辑：答案：我有两个相同背景的节点，所以背景被包裹，每次触摸屏幕时，背景向下移动50个像素。

   if bg.position.y + bg.size.height/2 < 50
    {
        let diff =  bg.position.y + bg.size.height/2 - 50
        bg.position.y = self.frame.height + bg.size.height/2 + diff
    }
    else
    {
        bg.position.y -= 50
    }
    if bg2.position.y + bg2.size.height/2 < 50
    {
        let diff =  bg2.position.y + bg2.size.height/2 - 50
        bg2.position.y = self.frame.height + bg2.size.height/2 + diff
    }
    else
    {
        bg2.position.y -= 50
    }

Answer 1

更改背景位置？

background.position.y += 50.0