滚动时获取UICollectionView的第一个单元格/项-iOS

Question

I have a UICollectionView with 1 row 1 column. I want to get the first item ( indexPath basically) when I am scrolling it horizontally.

For example, I have got 100 items displayed horizontally in my UICollectionView and when I scroll from right to left, whichever item is the first one visible, I need its indexPath . Which means the indexPath will be constantly changing while its scrolling.

How to achieve this? Please Guide. Thanks!

Answer 1

I think you need implement UIScrollView delegate method and get visible cell inside

- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView{
    UICollectionViewCell *firstCell = [[collectionView visibleCells] firstObject];
    NSIndexPath *firstIndexPath = [collectionView indexPathForCell: firstCell];
    NSLog(@"%@", firstIndexPath);
}

Hope this help

Answer 2

collectionView.indexPathsForVisibleItems() returns an array of NSIndexPath for visible cells. You can get the left most one by sorting them by NSIndexPath.item .

Edti : To be notified while scrolling, implement the UIScrollViewDelegate method scrollViewDidScroll(_: UIScrollView) . Remember that UICollectionView is a subclass of UIScrollView .