ios - 用 SKShapeNode 画一条线

Question

我想简单地使用 SKShapeNode 画一条线。我正在使用 SpriteKit 和 Swift。

到目前为止，这是我的代码：

var line = SKShapeNode()
var ref = CGPathCreateMutable()

    override func touchesBegan(touches: NSSet, withEvent event: UIEvent) {

    for touch: AnyObject in touches {
        let location = touch.locationInNode(self)

    }
}

override func touchesMoved(touches: NSSet, withEvent event: UIEvent) {

    for touch: AnyObject in touches {
        let locationInScene = touch.locationInNode(self)

        CGPathMoveToPoint(ref, nil, locationInScene.x, locationInScene.y)
        CGPathAddLineToPoint(ref, nil, locationInScene.x, locationInScene.y)
        line.path = ref
        line.lineWidth = 4
        line.fillColor = UIColor.redColor()
        line.strokeColor = UIColor.redColor()
        self.addChild(line)

    }
}

每当我运行它并尝试画一条线时，应用程序崩溃并出现错误：原因：'尝试添加一个已经有父节点的 SKNode：SKShapeNode 名称：'（null）'累积帧：{{0、0}、{0 , 0}}'

为什么会这样？

Answer 1

好吧，您一遍又一遍地添加相同的子实例。每次创建线节点，每次添加到父节点，就可以解决你的问题。

var ref = CGPathCreateMutable()

override func touchesBegan(touches: NSSet, withEvent event: UIEvent) {

    if let touch = touches.anyObject() as? UITouch {
        let location = touch.locationInNode(self)
        CGPathMoveToPoint(ref, nil, location.x, location.y)
    }
}

override func touchesMoved(touches: NSSet, withEvent event: UIEvent) {

    for touch: AnyObject in touches {
        let locationInScene = touch.locationInNode(self)
        var line = SKShapeNode()
        CGPathAddLineToPoint(ref, nil, locationInScene.x, locationInScene.y)
        line.path = ref
        line.lineWidth = 4
        line.fillColor = UIColor.redColor()
        line.strokeColor = UIColor.redColor()
        self.addChild(line)
    }
}