ios - 在 UIViewController 显示为 3DTouch 预览时检测 UITouches

Question

是否可以从当前用作 3D Touch 的 previewingContext View Controller 的 UIViewController 检测触摸并获取触摸位置？ (我想在触摸从左向右移动时更改预览 Controller 内的图像)

我已经尝试了 touchesBegan 和 touchesMoved 它们都没有被触发。

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

如果您想获得与 FaceBook 的 3D Touch 功能相同的结果，您需要创建自己的 3D Touch 手势类

    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 方法中的 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 Storyboard 中管理您的 Controller UI。在UICollectionView和UIImageView上方中间添加cover view，并在代码中与IBOutlets连接。

现在您可以为手势添加处理程序方法

func imagePressed(发件人:ForceTouchGestureRecognizer){

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

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

让 image = self.images[indexPath.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
}

从这一点开始，您需要自定义您的 View ，使其看起来与 Facebook 相同。

我还在 GitHub 上创建了一个小示例项目 https://github.com/ChernyshenkoTaras/3DTouchExample演示一下