Question

场景如下：用户点击并按住手指向左滑动UIView，以显示下面的另一个视图。可见视图向左滚动50点，然后停止。 View的框架以-50

转换

在所有这些时间中，用户持续按住Tap并最终将方向更改为向右并可以滚动直到视图到达其帧平移为0的初始位置。

问题是，当用户滚动到帧停止处的-50固定点之外时，平移仍会保留，并且当用户将滑动方向更改为右侧时，视图会以我想消除的差异移动。翻译的差异似乎是从视图的停止点到用户更改滑动方向的点。这是我的代码：

class ViewController: UIViewController {
    override func viewDidLoad() {
        super.viewDidLoad()
        drabbleLayer.isUserInteractionEnabled = true
        let recognizer = UIPanGestureRecognizer(target: self, action: #selector(handlePan(recognizer:)))
       drabbleLayer.addGestureRecognizer(recognizer)
    }

    @objc func handlePan(recognizer: UIPanGestureRecognizer) {
        if recognizer.state == .began {
            originalCenter = self.drabbleLayer!.center
        }

        var velocity = recognizer.velocity(in: drabbleLayer)

        if recognizer.state == .changed {

            let targetX: CGFloat = -50.0

            var tranlastion = recognizer.translation(in: self.drabbleLayer!)

            var newX: CGFloat {
                return originalCenter.x + tranlastion.x
            }

            if velocity.x < 0 {

                let log = tranlastion.x >= targetX
                let log2 = drabbleLayer.frame.origin.x >= targetX

                if  log && log2 {

                    dabbleLayer!.center.x = newX

                } else { drabbleLayer.center.x = -targetX * 2}

            } else {
                //this is where the Difference in Translation is noticeable if user swipes way beyond the stopping point to the left 
                if drabbleLayer.frame.origin.x <= 0 {
                    drabbleLayer!.center.x = newX

                } else {
                    //here view has to get to a full stop. Doesn't seem to work properly. 
                    drabbleLayer.frame.orgin.x = 0}
            }
        }
}

在我的完整代码中，我打印了转换值，以便查看更改的位置。我正在检查速度方向。问题是，改变方向后，转换形式从-74到200。在这种情况下，差异将是74（translation）-50（这是停止点，在我的代码中为targetX。而且，这种差异似乎如果用户从右向左滑动，也会显示。

我可以立即捕捉到翻译中的差异并以某种方式消除它吗？

Answer 1

最后，我找到了解决该问题的方法。我仍然找不到直接的解决方案，例如在改变方向之前保存翻译的最新值，以便我可以计算翻译的差异。

但是，在改变方向之前，我确实将平移设置为targetX值，因此不再需要减去平移的任何差异。这是我的新代码：

@objc func handlePan(recognizer: UIPanGestureRecognizer) {

    var tranlastion = recognizer.translation(in: self.incomeDrabbleLayer!)

    var newX: CGFloat {
        return originalCenter.x + tranlastion.x
    }

    let targetX: CGFloat = -50.0

    if recognizer.state == .began {
        originalCenter = self.incomeDrabbleLayer!.center
    }

    let velocity = recognizer.velocity(in: incomeDrabbleLayer)

    if recognizer.state == .changed {

        if velocity.x < 0 {
            if incomeDrabbleLayer.frame.origin.x > targetX {

                incomeDrabbleLayer.center.x = newX

            } else {

                incomeDrabbleLayer.frame.origin.x = targetX

                let targetTranslationPoint = CGPoint(x: targetX, y: 0)
                recognizer.setTranslation(targetTranslationPoint, in: incomeDrabbleLayer)
            }

        } else {

            if incomeDrabbleLayer.frame.origin.x < 0 {
                incomeDrabbleLayer.center.x = newX
            } else {
                incomeDrabbleLayer.frame.origin.x = 0
                recognizer.setTranslation(.zero, in: incomeDrabbleLayer)
            }

        }
    }

}

通过向左滑动框架到固定点，然后向右滑动以更新框架来改变方向，从而获得运动平移差异

1 个答案: