在swift 3中从触摸位置获取矢量

Question

正如标题所说，我该如何做到这一点?我可以获得第一个触控，但我不知道如果是滑动手势，如何获得最后一个触控。使用以下代码，我得到错误:类型'Set'的值没有成员'last'。我不太确定当触摸被释放时如何获得位置。

override func touchesMoved(_ touches: Set<UITouch>, with: UIEvent?){
    let firstTouch:UITouch = touches.first! as UITouch
    let lastTouch:UITouch = touches.last! as UITouch
    let firstTouchLocation = firstTouch.location(in: self)
    let lastTouchLocation = lastTouch.location(in: self)
}

我想要得到第一个点和第二个点的位置。然后，我想使用滑动的持续时间，线的大小和线的角度来创建一个用于SKNode的脉冲矢量。是否有任何方法可以使用UITouch提取这些信息?非常感谢任何帮助。谢谢你的时间!

我在屏幕上也有一些基本的触摸来运行函数

 override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
    let touch:UITouch = touches.first! as UITouch
    let touchLocation = touch.location(in: self)
    if playButton.contains(touchLocation) && proceed == true{
        playSound1()
        Ball.physicsBody?.affectedByGravity = true
        proceed = false}
    else if infoButton.contains(touchLocation) && proceed == true{
        playSound1()
        loadScene2()}
    else {}
}

Answer 1

你必须在touchesbegan中存储值并与touchesended中的值进行比较，然后在那里进行计算。请注意，触摸可以被电话之类的东西取消，所以你也需要预料到这一点。

    class v: UIViewController {
        var startPoint: CGPoint?
        var touchTime = NSDate()
        override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
            guard touches.count == 1 else {
                return
            }
            if let touch = touches.first {
                startPoint = touch.location(in: view)
                touchTime = NSDate()
            }
        }
        override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent?) {
            defer {
                startPoint = nil
            }
            guard touches.count == 1, let startPoint = startPoint else {
                return
            }
            if let touch = touches.first {
                let endPoint = touch.location(in: view)
                //Calculate your vector from the delta and what not here
                let direction = CGVector(dx: endPoint.x - startPoint.x, dy: endPoint.y - startPoint.y)
                let elapsedTime = touchTime.timeIntervalSinceNow
                let angle = atan2f(Float(direction.dy), Float(direction.dx))
            }
        }
        override func touchesCancelled(_ touches: Set<UITouch>, with event: UIEvent?) {
            startPoint = nil
        }
    }