swift - 如何获得滑动/拖动触摸的增量

Question

我想计算滑动手势或拖动手势之间的增量。我想要做的是获得这个增量，然后将其用作速度(通过添加时间变量)。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。现在我设置并获得了屏幕上的第一次触摸，但我不知道如何获得最后一次触摸，所以我可以计算矢量。谁能帮我解决这个问题？

现在我正在通过 touchesBegan 和 touchesEnded 这样做，我不确定它是否正确和更好的方法，这是我目前的代码:

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))
}

Answer 1

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、拖动或轻弹之间的区别。

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

在touchesBegan中，存放了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
}