用SKShapeNode画一条线

Question

我想简单地使用SKShapeNode绘制一条线.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绘制一条线时,应用程序崩溃并出现错误:reason:'尝试添加已经拥有父级的SKNode:SKShapeNode名称:'(null)'accumulationFrame:{{0,0}},{0 ,0}}'

为什么会这样？

Answer 1

那么你一遍又一遍地添加相同的子实例.每次创建行节点并每次将其添加到父节点,然后它将解决您的问题.

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)
    }
}