// 1、在创建collectionView的时候注册cell（一个分区）
UICollectionViewCell *cell=[collectionView dequeueReusableCellWithReuseIdentifier:@“cell" forIndexPath:indexPath];
for(UIView *view in cell.contentView.subviews) {
[view removeFromSuperview];
}
// 2、在cellForItem方法中注册cell（多个分区）
NSString *identifier=[NSString stringWithFormat:@"%ld%ld",(long)indexPath.section,(long)indexPath.row];
[collect registerClass:[UICollectionViewCellclass] forCellWithReuseIdentifier:identifier];
UICollectionViewCell *cell=[collectionView dequeueReusableCellWithReuseIdentifier:identifier forIndexPath:indexPath];
for(id subView in cell.contentView.subviews){
if(subView){
[subView removeFromSuperview];
}
}
