ios 如何从 UICollectionView 检测滚动方向？
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How can I detect the scroll direction from the UICollectionView?
提问by Soner Güler
I have a UICollectionView. I want to detect scroll direction. I have a two different animation style for scroll down and scroll up. So I must learn scroll direction.
我有一个 UICollectionView。我想检测滚动方向。我有两种不同的动画样式用于向下滚动和向上滚动。所以我必须学习滚动方向。
CGPoint scrollVelocity = [self.collectionView.panGestureRecognizer
velocityInView:self.collectionView.superview];
if (scrollVelocity.y > 0.0f)
NSLog(@"scroll up");
else if(scrollVelocity.y < 0.0f)
NSLog(@"scroll down");
This is just work at finger touched. Not work for me
这只是手指触摸的工作。不适合我
回答by Douglas Ferreira
Try this:
尝试这个：
Add this somewhere in you header:
在标题中的某处添加：
@property (nonatomic) CGFloat lastContentOffset;
Then override the scrollViewDidScroll:method:
然后重写scrollViewDidScroll:方法：
#pragma mark - UIScrollViewDelegate
- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
if (self.lastContentOffset > scrollView.contentOffset.y)
{
NSLog(@"Scrolling Up");
}
else if (self.lastContentOffset < scrollView.contentOffset.y)
{
NSLog(@"Scrolling Down");
}
self.lastContentOffset = scrollView.contentOffset.y;
}
Found in Finding the direction of scrolling in a UIScrollView?
回答by Patel Jigar
this is the best way to get scroll direction, hope this helps you
这是获得滚动方向的最佳方式，希望对您有所帮助
- (void)scrollViewWillEndDragging:(UIScrollView *)scrollView withVelocity:(CGPoint)velocity targetContentOffset:(inout CGPoint *)targetContentOffset {
CGPoint targetPoint = *targetContentOffset;
CGPoint currentPoint = scrollView.contentOffset;
if (targetPoint.y > currentPoint.y) {
NSLog(@"up");
}
else {
NSLog(@"down");
}
}
回答by genius
Swift 4.2
斯威夫特 4.2
private var lastContentOffset: CGFloat = 0
func scrollViewDidScroll(_ scrollView: UIScrollView) {
if lastContentOffset > scrollView.contentOffset.y && lastContentOffset < scrollView.contentSize.height - scrollView.frame.height {
// move up
print("move up")
originalHeight ()
} else if lastContentOffset < scrollView.contentOffset.y && scrollView.contentOffset.y > 0 {
// move down
print("move down")
minimizeHeaderView()
}
// update the new position acquired
lastContentOffset = scrollView.contentOffset.y
}
回答by Robin Delaporte
I was trying to find a way to detect if the user is mostly trying to pull vertically or horizontally the scrollView. I give you my solution, I hope it can be useful to anyone :
我试图找到一种方法来检测用户是否主要尝试垂直或水平拉动滚动视图。我给你我的解决方案，我希望它对任何人有用：
CGPoint _lastContentOffset;
- (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView {
_lastContentOffset = scrollView.contentOffset;
}
- (void)scrollViewDidScroll:(UIScrollView *)scrollView {
if (ABS(_lastContentOffset.x - scrollView.contentOffset.x) < ABS(_lastContentOffset.y - scrollView.contentOffset.y)) {
NSLog(@"Scrolled Vertically");
} else {
NSLog(@"Scrolled Horizontally");
}
}
This work find for me and I use this to avoid the scrollView to move horizontally when scrolling vertically and opposite.
这项工作适合我，我使用它来避免在垂直和相反滚动时 scrollView 水平移动。
