iOS collectionView adds subviews under the cell

        if ([scrollView isKindOfClass:[UITableView class]] ||
            [scrollView isKindOfClass:[UICollectionView class]]) {
            [scrollView aspect_hookSelector:@selector(reloadData) withOptions:AspectPositionAfter usingBlock:^(){
                [weakScrollView insertSubview:headerConfig.backgroundView atIndex:0];
            } error:nil];
        }

Requirements: add backgroundView to the cell of collectionView,

To wait until collecitonView has executed reloadData, then execute

  [collecitonView insertSubview：backgroundView atIndex:0];

Note: must be after reloadData

demo