计算旋转速度并自然旋转视图iOS

I have a circle-shaped view and have it rotate via the following code overriding touchesBegan(touches:, withEvent:) and touchesMoved(touches:, withEvent:).

我有一个圆形的视图，并通过以下代码旋转覆盖touchesBegan（touches：，withEvent :)和touchesMoved（touches：，withEvent :)。

var deltaAngle = CGFloat(0)
var startTransform: CGAffineTransform?

override func touchesBegan(touches: Set<UITouch>, withEvent event: UIEvent?)
{
    let touchPoint = touches.first!.locationInView(view)

    let dx = touchPoint.x - view.center.x
    let dy = touchPoint.y - view.center.y

    deltaAngle = atan2(dy, dx)
    startTransform = arrowPickerView.transform
}

override func touchesMoved(touches: Set<UITouch>, withEvent event: UIEvent?)
{
    let touchPoint = touches.first!.locationInView(view)

    let dx = touchPoint.x - view.center.x
    let dy = touchPoint.y - view.center.y
    let angle = atan2(dy, dx)
    let angleDifference = deltaAngle - angle
    let transform = CGAffineTransformRotate(startTransform!, -angleDifference)
    arrowPickerView.transform = transform
}

I want to override touchesEnded(touches:, withEvent:) to calculate the velocity and have the view naturally rotate a little (similar to continuous scrolling). I currently save the original transform and calculate the delta angle. How can I implement this? Thanks in advance!

我想覆盖touchesEnded（touches：，withEvent :)来计算速度并让视图自然旋转一点（类似于连续滚动）。我目前保存原始变换并计算delta角度。我该如何实现呢？提前致谢！

1 个解决方案

#1

In my example below, the CGAffineTransformRotate depends on:

在下面的示例中，CGAffineTransformRotate取决于：

direction (if the user moves from left to right, up or down etc)
方向（如果用户从左向右移动，向上或向下移动等）
rotation (a factor dependent on the time between touchesBegan and touchesEnded)
旋转（取决于touchesBegan和touchesEnded之间的时间因素）
PI
PI

This creates an CGAffineTransformRotate and this rotates with duration 1 (s), to create a feel of kinetic scrolling the UIViewAnimationOptions.CurveEaseOut property is used

这将创建一个CGAffineTransformRotate，并以1（s）的持续时间旋转，以创建动态滚动的感觉UIViewAnimationOptions.CurveEaseOut属性被使用

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

    let touchPointEnd = touches.first!.locationInView(view)

    self.dateTouchesEnded = NSDate()

    let delay : NSTimeInterval = NSTimeInterval(0)

    let timeDelta : Double = self.dateTouchesEnded!.timeIntervalSince1970 - self.dateTouchesStarted!.timeIntervalSince1970

    let horizontalDistance : Double = Double(touchPointEnd.x - self.touchPointStart!.x)
    let verticalDistance : Double = Double(touchPointEnd.y - self.touchPointStart!.y)

    var direction : Double = 1
    if (fabs(horizontalDistance) > fabs(verticalDistance)) {
        if horizontalDistance > 0 {
            direction = -1
        }
    } else {
        if verticalDistance < 0 {
            direction = -1
        }
    }

    let rotation : Double = (0.1 / timeDelta < 0.99) ? 0.1 / timeDelta : 0.99

    let duration : NSTimeInterval = NSTimeInterval(1)
    UIView.animateWithDuration(duration, delay: delay, options: UIViewAnimationOptions.CurveEaseOut, animations: {
        let transform = CGAffineTransformRotate(self.imageView.transform, CGFloat(direction) * CGFloat(rotation) * CGFloat(M_PI))
        self.imageView.transform = transform
        }, completion: nil)

}

I added the variables to keep track of the start and end time of touches and added the CGPoint location of the touchesBegan function

我添加了变量来跟踪触摸的开始和结束时间，并添加了touchesBegan函数的CGPoint位置

var dateTouchesStarted : NSDate?
var dateTouchesEnded : NSDate?
var touchPointStart : CGPoint?

In touchesBegan i added:

在touchesBegan我添加：

self.touchPointStart = touchPoint

To set the variable as explained above.

如上所述设置变量。

#1