用手指更准确地拖动 SKSprite 节点或 UIImage，保持偏移？

Question

我正在尝试用手指更准确地拖动 SKSprite 节点或 UIImage。例如，如果在节点的底角注册并移动了触摸，我希望图像保持您的手指位置与节点中心之间的距离。当前中心位置跳转到手指位置。

这是我的代码，似乎没有维护偏移代码（touchl - previousLocation）。 有什么建议吗？

override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) {
        for touch in touches {
            let touchl = touch.location(in: self)
            let previousLocation = touch.previousLocation(in: self)
                       triangle.position.x = touchl.x + (touchl.x - previousLocation.x)
                       triangle.position.y = touchl.y + (touchl.y - previousLocation.y)
                       }
            }

Answer 1

override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) {
    for touch in touches {
        let touchl = touch.location(in: self)
        let previousLocation = touch.previousLocation(in: self)
        let dx = touchl.x - previousLocation.x
        let dy = touchl.y - previousLocation.y
        
            triangle.position.x = triangle.position.x + dx
            triangle.position.y = triangle.position.y + dy
        }
       }