如何在Swift 3.0中拖放精灵？

我所要做的就是能够在屏幕上拖放一个精灵.我试过以下代码：

override func touchesBegan(touches: Set<UITouch>,withEvent event: UIEvent?) {
}

override func touchesMoved(touches: Set<UITouch>,withEvent event: UIEvent?) {
    for touch in (touches ) {
        let location = touch.locationInNode(self)
        if ball.containsPoint(location) {
            ball.position = location    
}
}
}

这段代码确实有效,但是当我快速拖动球时,我猜它会检测到“球”不再包含点“位置”并且球停止,这意味着我再次接球.我希望球能够快速响应我的触球,这样球就不会停止移动.我该怎么办？

我有一个实现,我已经将UIImageView子类化并称之为“DraggableImage”

override func touchesBegan(_ touches: Set<UITouch>,with event: UIEvent?) {
        originalPosition = self.center
    }

override func touchesMoved(_ touches: Set<UITouch>,with event: UIEvent?) {
        if let touch = touches.first {
            let position = touch.location(in: self.superview)
            self.center = CGPoint(x: position.x,y: position.y)
        }
    }

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

        self.center = originalPosition
    }