//在創建collectionView的時候注冊cell（一個分區）UICollectionViewCell *cell=[collectionView dequeueReusableCellWithReuseIdentifier:@“cell" forIndexPath:indexPath];  for (UIView *view in cell.contentView.subviews) {    [view removeFromSuperview];  }

//在cellForItem方法中注冊cell（多個分區） NSString *identifier=[NSString stringWithFormat:@"%ld%ld",(long)indexPath.section,(long)indexPath.row];    [collect registerClass:[UICollectionViewCell class] forCellWithReuseIdentifier:identifier];    UICollectionViewCell *cell=[collectionView dequeueReusableCellWithReuseIdentifier:identifier forIndexPath:indexPath];    for(id subView in cell.contentView.subviews){        if(subView){            [subView removeFromSuperview];    }      }