我正在尝试使用 UICollectionView 实现“无限滚动”。
我通过像 this tutorial 中那样缓冲我的数据数组来做到这一点
然后通过以下方式实现 UICollectionViewDelegate 的 didEndDisplayingCell:
- (void)collectionView:(UICollectionView *)collectionView didEndDisplayingCell:(UICollectionViewCell *)cell forItemAtIndexPath:(NSIndexPath *)indexPath{
if (self.galleryArray.count > 0) {
NSIndexPath *newIndexPath = indexPath;
if (self.specialHeaderView.bannerView.scrollDirection == left) {
newIndexPath = [NSIndexPath indexPathForItem:indexPath.row - 1 inSection:indexPath.section];
} else if (self.specialHeaderView.bannerView.scrollDirection == right) {
newIndexPath = [NSIndexPath indexPathForItem:indexPath.row + 1 inSection:indexPath.section];
}
if (newIndexPath.row == (self.galleryArray.count - 1)) {
// user is scrolling to the right from the last item to the 'fake' item 1.
// reposition offset to show the 'real' item 1 at the left-hand end of the collection view
newIndexPath = [NSIndexPath indexPathForItem:1 inSection:indexPath.section];
[self.bannerCollectionView scrollToItemAtIndexPath:newIndexPath atScrollPosition:UICollectionViewScrollPositionLeft animated:NO];
return;
}
// if (scrollView.contentOffset.x == self.collectionView.frame.size.width) {
if (newIndexPath.row == 0) {
// user is scrolling to the left from the first item to the fake 'item N'.
// reposition offset to show the 'real' item N at the right end end of the collection view
newIndexPath = [NSIndexPath indexPathForItem:([self.galleryArray count] -2) inSection:indexPath.section];
[self.bannerCollectionView scrollToItemAtIndexPath:newIndexPath atScrollPosition:UICollectionViewScrollPositionLeft animated:NO];
}
}
问题是，每当调用 didEndDisplayingCell 方法并且 Collection View 通过它的委托(delegate) CellForItemAtIndexPath 方法请求一个单元格时，该单元格就会隐藏起来。
这是我的CellForItemAtIndexPath 实现:
-(UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath {
SpecialBannerCell *specialBannerCell = (SpecialBannerCell *)[collectionView dequeueReusableCellWithReuseIdentifier:GalleryCellIdentifier forIndexPath:indexPath];
if (specialBannerCell.hidden) {
}
Benefit *benefit = [self.galleryArray objectAtIndex:indexPath.row];
[specialBannerCell.imageBanner setImageWithURL:[NSURL URLWithString:benefit.imageIphoneUrl] placeholderImage:[UIImage imageNamed:@"photo_loader"]];
return specialBannerCell;
我在这里做错了什么？
最佳答案
所以我不确定为什么，但是当我使用 UIScrollViewDelegate 方法而不是 didEndDisplayingCell 方法时，单元格不再隐藏并且一切正常。
- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView {
if (self.galleryArray.count > 0) {
NSIndexPath *indexPath = self.currentIndexPath;
NSIndexPath *newIndexPath = indexPath;
if (newIndexPath.row == (self.galleryArray.count - 1)) {
// user is scrolling to the right from the last item to the 'fake' item 1.
// reposition offset to show the 'real' item 1 at the left-hand end of the collection view
newIndexPath = [NSIndexPath indexPathForItem:1 inSection:indexPath.section];
self.currentIndexPath = newIndexPath;
[self.bannerCollectionView scrollToItemAtIndexPath:newIndexPath atScrollPosition:UICollectionViewScrollPositionLeft animated:NO];
return;
}
if (newIndexPath.row == 0) {
// user is scrolling to the left from the first item to the fake 'item N'.
// reposition offset to show the 'real' item N at the right end end of the collection view
newIndexPath = [NSIndexPath indexPathForItem:([self.galleryArray count] -2) inSection:indexPath.section];
self.currentIndexPath = newIndexPath;
[self.bannerCollectionView scrollToItemAtIndexPath:newIndexPath atScrollPosition:UICollectionViewScrollPositionLeft animated:NO];
}
}
关于ios - UICollectionViewCell 变为隐藏=YES，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/24352030/