如何获得滑动/拖动触摸的增量

Posted 2021-04-21

我想计算滑动手势或拖动手势之间的差值。我想要做的是获得此delta，然后将其用作速度（通过添加时间var）。我真的很困惑我应该怎么做 - 通过touchesMoved或通过UIPanGestureRecognizer。另外，我真的不明白它们之间的区别。现在我设置并在屏幕上第一次触摸，但我不知道如何获得最后一个，所以我可以计算向量。任何人都可以帮助我吗？

现在我通过touchesBegan和touchesEnded这样做，我不确定它是否正确和更好的方式，这是我的代码到目前为止：

class GameScene: SKScene {
var start: CGPoint?
var end: CGPoint?


override func didMove(to view: SKView) {        

}

override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
    guard let touch = touches.first else {return}
    self.start = touch.location(in: self)
    print("start point: ", start!)
}

override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent?) {
    guard let touch = touches.first else {return}
    self.end = touch.location(in: self)
    print("end point: ", end!)

    let deltax:CGFloat = ((self.start?.x)! - (self.end?.x)!)
    let deltay:CGFloat = ((self.start?.y)! - (self.end?.y)!)
    print(UInt(deltax))
    print(UInt(deltay))
}

答案

您可以使用SpriteKit的内置触摸处理程序检测滑动手势，或者您可以实现UISwipeGestureRecognizer。以下是如何使用SpriteKit的触摸处理程序检测滑动手势的示例：

首先，定义变量和常量......

定义初始触摸的起点和时间。

var touchStart: CGPoint?
var startTime : TimeInterval?

定义指定滑动手势特征的常量。通过更改这些常量，您可以检测滑动，拖动或轻弹之间的差异。

let minSpeed:CGFloat = 1000
let maxSpeed:CGFloat = 5000
let minDistance:CGFloat = 25
let minDuration:TimeInterval = 0.1

在touchesBegan中，存储初始触摸的起点和时间

override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {
    touchStart = touches.first?.location(in: self)
    startTime = touches.first?.timestamp
}

在touchesEnded中，计算手势的距离，持续时间和速度。将这些值与常量进行比较，以确定手势是否为滑动。

override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent?) {
    guard let touchStart = self.touchStart else {
        return
    }
    guard let startTime = self.startTime else {
        return
    }
    guard let location = touches.first?.location(in: self) else {
        return
    }
    guard let time = touches.first?.timestamp else {
        return
    }
    var dx = location.x - touchStart.x
    var dy = location.y - touchStart.y
    // Distance of the gesture
    let distance = sqrt(dx*dx+dy*dy)
    if distance >= minDistance {
        // Duration of the gesture
        let deltaTime = time - startTime
        if deltaTime > minDuration {
            // Speed of the gesture
            let speed = distance / CGFloat(deltaTime)
            if speed >= minSpeed && speed <= maxSpeed {
                // Normalize by distance to obtain unit vector
                dx /= distance
                dy /= distance
                // Swipe detected
                print("Swipe detected with speed = (speed) and direction ((dx), (dy)")
            }
        }
    }
    // Reset variables
    touchStart = nil
    startTime = nil
}