我有一个UICollectionView，在滚动的情况下停止更新单元格。 它加载了几个单元格，但是当我向下滚动或向上滚动时，UIcollectionView的其余部分是空的，尽管比例较大，几个单元格的大小可见。

当我滚动得非常快时，发生的情况会更多，随机调用cellForItemAtIndexPath并且UICollectionView只显示最后加载的单元格，其余空格为空。

这是我的代码：

[self.collectionView registerNib:[UINib nibWithNibName:NSStringFromClass([NewsCollectionViewCell class]) bundle:nil] forCellWithReuseIdentifier:NSStringFromClass([NewsCollectionViewCell class])];

[self.collectionView registerClass:[NewsHeaderCollectionReusableView class]  forSupplementaryViewOfKind:UICollectionElementKindSectionHeader withReuseIdentifier:NSStringFromClass([NewsHeaderCollectionReusableView class])];

编注标记UICollectionViewDataSource

- (NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView
{
return 1;
}

- (NSInteger)collectionView:(UICollectionView *)collectionView
 numberOfItemsInSection:(NSInteger)section
{
return self.newsArray.count;
}

- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView
              cellForItemAtIndexPath:(NSIndexPath *)indexPath
{
NewsCollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:NSStringFromClass([NewsCollectionViewCell class]) forIndexPath:indexPath];

[cell refreshWithContentModel:self.newsArray[indexPath.item]];

return cell;
}

- (UICollectionReusableView *)collectionView:(UICollectionView *)collectionView
       viewForSupplementaryElementOfKind:(NSString *)kind
                             atIndexPath:(NSIndexPath *)indexPath
{
NewsHeaderCollectionReusableView *collectionReusableView = [collectionView dequeueReusableSupplementaryViewOfKind:UICollectionElementKindSectionHeader withReuseIdentifier:NSStringFromClass([NewsHeaderCollectionReusableView class]) forIndexPath:indexPath];

if (self.newsArray.count) {
    [collectionReusableView refreshWithContentModel:self.newsArray[0]];
}

return collectionReusableView;
}

编译标记UICollectionViewDelegate

- (void)collectionView:(UICollectionView *)collectionView willDisplayCell:(UICollectionViewCell *)cell forItemAtIndexPath:(NSIndexPath *)indexPath
{
if (indexPath.item == self.newsArray.count - 1) {
    [self addMoreNews]; // add items to array and call collection reloaddata
}
}

编注标记UICollectionViewDelegateFlowLayout

- (CGSize)collectionView:(UICollectionView *)collectionView
              layout:(UICollectionViewLayout *)collectionViewLayout sizeForItemAtIndexPath:(NSIndexPath *)indexPath
{    
return CGSizeMake(ceilf(self.collectionView.bounds.size.width / 3.0) - 10, ceilf(self.collectionView.bounds.size.height / 3.0));
}

- (CGSize)collectionView:(UICollectionView *)collectionView
              layout:(UICollectionViewLayout *)collectionViewLayout referenceSizeForHeaderInSection:(NSInteger)section
{

return CGSizeMake(self.collectionView.bounds.size.width, ceilf(self.collectionView.bounds.size.height / 2.0));
}

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