[英]iOS - swipe UICollectionViewCell horizontally
毕竟,我找到了一种使用UIPanGestureRecognizer
进行操作的方法。 所有操作都在单元格上(单元格类内部)。 下面是对我有用的解决方案
var swipeGesture: UIPanGestureRecognizer!
var originalPoint: CGPoint!
func configureCell() {
setupSwipeGesture()
}
func setupSwipeGesture() {
swipeGesture = UIPanGestureRecognizer(target: self, action:#selector(swiped(_:)))
swipeGesture.delegate = self
self.addGestureRecognizer(swipeGesture)
}
func swiped(_ gestureRecognizer: UIPanGestureRecognizer) {
let xDistance:CGFloat = gestureRecognizer.translation(in: self).x
switch(gestureRecognizer.state) {
case UIGestureRecognizerState.began:
self.originalPoint = self.center
case UIGestureRecognizerState.changed:
let translation: CGPoint = gestureRecognizer.translation(in: self)
let displacement: CGPoint = CGPoint.init(x: translation.x, y: translation.y)
if displacement.x + self.originalPoint.x < self.originalPoint.x {
self.transform = CGAffineTransform.init(translationX: displacement.x, y: 0)
self.center = CGPoint(x: self.originalPoint.x + xDistance, y: self.originalPoint.y)
}
case UIGestureRecognizerState.ended:
let hasMovedToFarLeft = self.frame.maxX < UIScreen.main.bounds.width / 2
if (hasMovedToFarLeft) {
removeViewFromParentWithAnimation()
} else {
resetViewPositionAndTransformations()
}
default:
break
}
}
func resetViewPositionAndTransformations(){
UIView.animate(withDuration: 0.5, delay: 0.0, usingSpringWithDamping: 0.8, initialSpringVelocity: 0.0, options: UIViewAnimationOptions(), animations: {
self.center = self.originalPoint
self.transform = CGAffineTransform(rotationAngle: 0)
}, completion: {success in })
}
func removeViewFromParentWithAnimation() {
var animations:(()->Void)!
animations = {self.center.x = -self.frame.width}
UIView.animate(withDuration: 0.2, animations: animations , completion: {success in self.removeFromSuperview()})
}
您将需要做一些事情:
1)向每个单元格添加一个UISwipeGestureRecognizer
。 确保将direction = .left
设置direction = .left
。
2)为手势识别器添加目标,并确保目标可以与集合视图的布局通信。 2a)集合视图数据源可以将目标添加到cellForItemAtIndexPath
。 您需要一种方法来确保它不会在重复使用的单元格上重复添加。 2b)您可以在单元格中添加手势识别器,并与视图控制器创建委托关系。
3)您将需要被刷过的单元格的索引路径。 要从手势识别器(2a)中获取单元格,请调用其view
属性并转换为UICollectionViewCell。 如果使用委托(2b)或其他方法,则应将单元格传回。 然后,您可以调用collectionView.cellForItem(at indexPath: IndexPath) -> UICollectionViewCell?
获取索引路径。
4)在集合视图, performBatchUpdates
等中调用deleteItemAtIndexPath:
5)似乎可以用动画的方式简化左边的消失(免责声明,尽管我已经使用过属性,但我自己还没有完成这部分工作)是在UICollectionViewLayout的子类中实现finalLayoutAttributesForDisappearingItemAtIndexPath :。
首先,您需要缓存属性。 因此,覆盖并缓存:
class LeftDisappearLayout : UICollectionViewFLowLayout {
var cachedAttributes = [NSIndexPath:UICollectionViewAttributes?]()
override func layoutAttributesForItem(at indexPath: IndexPath) -> UICollectionViewLayoutAttributes? {
let attributes = super.layoutAttributesForItem(at: indexPath)
cachedAttributes[indexPath] = attributes
return attributes
}
然后从iOS 9开始,出现了一种简单的方法让系统为您创建左侧动画:
func finalLayoutAttributesForDisappearingItem(at itemIndexPath: IndexPath) -> UICollectionViewLayoutAttributes? {
if var attributes = cachedAttributes[indexPath] {
let newCenterX : CGFloat = -1 * (attributes.frame.size.width / 2)
attributes.center = CGPoint(newCenterX, attributes.center.y)
return attributes
}
AssertionFailure("Unable to find cached attributes!") // Saying, "This should never happen and in development crash to alert the developer, but in production gracefully revert to default."
return nil
}
}
确保将您的收藏夹视图设置为使用此布局。 希望这可以帮助。
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