UIPanGesture 识别器仅向一个方向滑动

Question

我正在开发 UIPanGestureRecognizer，对我来说它正在工作。但我在这里遇到了一些问题，因为我是 iOS 新手，刚刚从 Android 转移到 iOS。 先看看我要做什么：

我想要什么：我有一个 UITableView，我想在单元格上执行滑动。我只想将它们从左向右拖动并移动/删除该单元格。与在android中完成的非常相似。

但我只想将项目移动到一个方向。那就是“从左到右”。但不是从右到左。现在在这里看看我到目前为止做了什么

我做了什么：

    @objc func handlePan(recognizer: UIPanGestureRecognizer) {
    // 1
    if recognizer.state == .began {
        // when the gesture begins, record the current center location
        originalCenter = center
        print("Center",originalCenter)

    }
    // 2
    if recognizer.state == .changed {
        let translation = recognizer.translation(in: self)


        center = CGPoint(x: originalCenter.x+translation.x, y: originalCenter.y)

        // has the user dragged the item far enough to initiate a delete/complete?
        deleteOnDragRelease = frame.origin.x < -frame.size.width / 2.0
        completeOnDragRelease = frame.origin.x > frame.size.width / 2.0
        // print ("FrameX = ",frame.origin.x , " , ","Width = ",frame.size.width / 2.0 , "Total = ",frame.origin.x < -frame.size.width / 2.0 )
        //print ("DelOnDrag = ",deleteOnDragRelease , " , ","CompOnDrag = ",completeOnDragRelease)

    }
    // 3
    if recognizer.state == .ended {
        // the frame this cell had before user dragged it
        let originalFrame = CGRect(x: 0, y: frame.origin.y,
                                   width: bounds.size.width, height: bounds.size.height)
        if deleteOnDragRelease {
            if delegate != nil && clickedItem != nil {
                // notify the delegate that this item should be deleted
                delegate!.toDoItemDeleted(clickedItem: clickedItem!)
            }
        } else if completeOnDragRelease {

            UIView.animate(withDuration: 8.2, animations: {self.frame = originalFrame})
        } else {
            UIView.animate(withDuration: 8.2, animations: {self.frame = originalFrame})
        }
    }
}

我知道我可以对 ".changed" 进行检查，并计算 X 值是否趋向于 0 或小于 0。但有一段时间它会从右向左移动项目。

问题：有什么方法可以得到接触点的 x 值吗？或者只是一些如何让用户想要从右向左滑动并阻止用户这样做？请分享你的知识

Answer 1

您的相同代码只需将您的 UIGestureRecognizer 方法中的一项更改替换为此代码即可解决您的问题。仅在您的 tableview 单元格上从左到右交换工作。任何重新评分的查询只需在下面发表评论。

override func gestureRecognizerShouldBegin(_ gestureRecognizer: UIGestureRecognizer) -> Bool {
        if let panGestureRecognizer = gestureRecognizer as? UIPanGestureRecognizer {
            let translation = panGestureRecognizer.translation(in: superview!)
            if translation.x >=  0 {
                return true
            }
            return false
        }
        return false
    }

祝你好运。

继续编码。

Answer 2

您可以使用以下扩展来做到这一点

extension UIPanGestureRecognizer {

    enum GestureDirection {
        case Up
        case Down
        case Left
        case Right
    }

    func verticalDirection(target: UIView) -> GestureDirection {
        return self.velocity(in: target).y > 0 ? .Down : .Up
    }

    func horizontalDirection(target: UIView) -> GestureDirection {
        return self.velocity(in: target).x > 0 ? .Right : .Left
    }   
}

你可以像下面这样得到方向

gestureRecognizer.horizontalDirection(target: self)