在UIViewController显示为3DTouch预览时检测UITouches

Question

是否可以从当前用作3D触摸的previewingContext视图控制器的UIViewController检测触摸并获得触摸的位置？(当触摸从左向右移动时，我希望更改预览控制器中的图像)

我已经试过touchesBegan和touchesMoved了，他们都没被解雇。

class ThreeDTouchPreviewController: UIViewController {

func getLocationFromTouch(touches: Set<UITouch>) -> CGPoint?{
        guard let touch  = touches.first else { return nil }
        return touch.location(in: self.view)
    }
    //Not fired
    override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent?) {

        let location = getLocationFromTouch(touches: touches)
        print("LOCATION", location)
    }
    //Not fired
    override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent?) {
        let location = getLocationFromTouch(touches: touches)
        print("LOCATION", location)
    }
}

甚至尝试添加一个UIPanGesture。

尝试复制FaceBook的3D Touch功能，用户可以从左向右移动手指来更改当前显示的图像。上下文视频：https://streamable.com/ilnln

Answer 1

如果你想获得和FaceBook 3D Touch功能一样的效果，你需要创建你自己的3D Touch gesture class

    import UIKit.UIGestureRecognizerSubclass

class ForceTouchGestureRecognizer: UIGestureRecognizer {

    var forceValue: CGFloat = 0
    var isForceTouch: Bool = false

    override func touchesBegan(_ touches: Set<UITouch>, with event: UIEvent) {
        super.touchesBegan(touches, with: event)
        handleForceWithTouches(touches: touches)
        state = .began
        self.isForceTouch = false
    }

    override func touchesMoved(_ touches: Set<UITouch>, with event: UIEvent) {
        super.touchesMoved(touches, with: event)
        handleForceWithTouches(touches: touches)
        if self.forceValue > 6.0 {
            state = .changed
            self.isForceTouch = true
        }
    }

    override func touchesEnded(_ touches: Set<UITouch>, with event: UIEvent) {
        super.touchesEnded(touches, with: event)
        state = .ended
        handleForceWithTouches(touches: touches)
    }

    override func touchesCancelled(_ touches: Set<UITouch>, with event: UIEvent) {
        super.touchesCancelled(touches, with: event)
        state = .cancelled
        handleForceWithTouches(touches: touches)
    }

    func handleForceWithTouches(touches: Set<UITouch>) {
        if touches.count != 1 {
            state = .failed
            return
        }

        guard let touch = touches.first else {
            state = .failed
            return
        }
        forceValue = touch.force
    }
}

现在，您可以在viewDidLoad方法的ViewController中添加此手势

override func viewDidLoad() {
    super.viewDidLoad()
    let gesture = ForceTouchGestureRecognizer(target: self, action: #selector(imagePressed(sender:)))
    self.view.addGestureRecognizer(gesture)
}

现在，您可以在故事板中管理控制器UI。在UICollectionView上添加cover view，在中间添加UIImageView，并在代码中将其与IBOutlets连接。

现在，您可以为手势添加处理程序方法

ForceTouchGestureRecognizer imagePressed(发送方: func ){

let location = sender.location(in: self.view)

guard let indexPath = collectionView?.indexPathForItem(
    at: location) else { return }

让图像= self.imagesindexPath.row

switch sender.state {
case .changed:
    if sender.isForceTouch {
        self.coverView?.isHidden = false
        self.selectedImageView?.isHidden = false
        self.selectedImageView?.image = image
    }

case .ended:
    print("force: \(sender.forceValue)")
    if sender.isForceTouch {
        self.coverView?.isHidden = true
        self.selectedImageView?.isHidden = true
        self.selectedImageView?.image = nil
    } else {
        //TODO: handle selecting items of UICollectionView here,
        //you can refer to this SO question for more info: https://stackoverflow.com/questions/42372609/collectionview-didnt-call-didselectitematindexpath-when-superview-has-gesture
        print("Did select row at indexPath: \(indexPath)")
        self.collectionView?.selectItem(at: indexPath, animated: true, scrollPosition: .centeredVertically)
    }

default: break
}

}

在这一点上，你需要定制你的视图，使它看起来像Facebook一样。

我还在GitHub https://github.com/ChernyshenkoTaras/3DTouchExample上创建了一个小示例项目来演示它