swift - 为什么我的 touchesEnded 函数没有初始化？

Question

代码将返回 x1 和 y1 值，但似乎并没有通过 touchesEnded 函数运行。我的目标是创建一个矩形，从用户触摸的角开始，到用户抬起手指的地方结束。

            //touch initialized
            override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
            for touch in touches {
            let location = touch.location(in: self)
            let x1 = location.x
            let y1 = location.y
            print(x1,y1)

        }

            func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent?){
            for touch in touches{

            let location2 = touch.location(in: self)
            let x2 = location2.x
            let y2 = location2.y
            let originX = min(x1,x2)
            let originY = min(y1,y2)
            let cornerX = max(x1,x2)
            let cornerY = max(y1,y2)
            let boxWidth = cornerX - originX
            let boxHeight = cornerY - originY

            let box = SKSpriteNode()
            box.size = CGSize(width: boxWidth, height: boxHeight)
            box.color = SKColor.black
            box.position = CGPoint(x:originX, y: originY)
            addChild(box)

            print(x1,y1,x2,y2)
            }
            }

Answer 1

您的代码中的问题是它缺少关闭 touchesBegan 的花括号，因此 touchesEnded 不允许被覆盖，因为从技术上讲它在您的 touchesBegan 中 而不是场景本身。

试试这个:

var x1: CGFloat = 0.0
var y1: CGFloat = 0.0

//...

//touch initialized
override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
    for touch in touches {
        let location = touch.location(in: self)
        x1 = location.x
        y1 = location.y
        print(x1,y1)
    }
}

override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent?){

    for touch in touches{
        let location2 = touch.location(in: self)
        let x2 = location2.x
        let y2 = location2.y
        let originX = min(x1,x2)
        let originY = min(y1,y2)
        let cornerX = max(x1,x2)
        let cornerY = max(y1,y2)
        let boxWidth = cornerX - originX
        let boxHeight = cornerY - originY
        let box = SKSpriteNode()
        box.size = CGSize(width: boxWidth, height: boxHeight)
        box.color = SKColor.black
        box.position = CGPoint(x:originX, y: originY)
        addChild(box)

        print(x1,y1,x2,y2)
    }
}

当然，我不会单独保存每个 x 和 y 坐标，而是只保存两个 CGPoints