在滑动手势，iOS，Swift上将视图更改为圆圈

Question

我正试图在滑动手势（任何方向，快或慢）上将视图缩小为圆形，类似于WhatsApp videoCall视图中的体验。请参阅下面的图片，了解我想要实现的目标。

我相信我需要使用滑动手势来实现这一点，我已经为我的videoView添加了一个滑动手势，我不知道下一步该做什么。

在viewDidLoad中我有以下

videoView.addGestureRecognizer(UISwipeGestureRecognizer(target: self, action: #selector(self.minimiseView) ))

我想我需要使用手势定位？而且我还需要设置随着滑动而增加的角半径。有人可以告诉我如何实现这个目标吗？

func minimiseView(gesture: UISwipeGestureRecognizer){
        let location = gesture.location(in: self.view)
    }

Answer 1

您基本上想要执行以下步骤：

1. 捕获起始手势位置
2. 在滑动过程中，测量与原始滑动的距离
3. 使用此距离可增加摄像机视图的角半径
   • e.g。设置cornerRadius = distanceSwiped
4. 一旦角半径达到一定量（并且视图为圆圈），捕捉当前手势位置
5. 使用此值可以再次开始跟踪动作并使用它来减小视图的宽度
6. 当视图足够小时将其解雇

以下是如何完成此操作的基本设置：

enum VideoDismissState {
    case cornerRadiusChanging, sizeChanging, complete
}

var initialGesturePosition: CGPoint = .zero
var maxCornerRadiusGesturePosition: CGPoint = .zero
var dismissState: VideoDismissState = .complete

func minimiseView(_ gesture: UISwipeGestureRecognizer) {
    let location = gesture.location(in: videoView)

    switch gesture.state {
    case .began:
        initialGesturePosition = gesture.location(in: videoView)
        dismissState = .cornerRadiusChanging
    case .changed:
        let currentPosition = gesture.location(in: videoView)

        switch dismissState {
        case cornerRadiusChanging:
            let swipeDistance = distance(between: initialGesturePosition, and: currentPosition)
            // play around with this formula to see what feels right
            videoView.layer.cornerRadius = swipeDistance / 2

            // at a certain point, switch to changing the size
            if swipeDistance >= videoView.width / 2 {
                maxCornerRadiusGesturePosition = currentPosition
                dismissState = .sizeChanging
            }
        case sizeChanging:
            let swipeDistance = distance(between: maxCornerGesturePosition, and: currentPosition)
            // again try different things to see what feels right here
            let scaleFactor = 50 / swipeDistance

            videoView.layer.transform = CGAffineTransform(scaledX: scaleFactor, y: scaleFactor

            if scaleFactor <= 0.2 {
                dismissState = .complete
            }
        case complete:
            // reset values
            initialGesturePosition = .zero
            maxCornerRadiusGesturePosition = .zero

            // dismiss videoView
            // for example: videoView.isHidden = true OR videoView.removeFromSuperview()
        }
    case .ended:
        // if the gesture ends too soon you may want to animate the view back to full screen
    }
}

/// Measure distance between two points
func distance(between first: CGPoint, and second: CGPoint) -> CGFloat {
    return sqrt((first.x - second.x) ^ 2 + (first.y - second.y) ^ 2)
}

这可能不完全正常，因为我没有测试过，但基本的想法应该足以让你开始。