//在創建collectionView的時候註冊cell（一個分區）
UICollectionViewCell *cell=[collectionView dequeueReusableCellWithReuseIdentifier:@“cell" forIndexPath:indexPath];
for (UIView *view in cell.contentView.subviews) {
[view removeFromSuperview];
}
二：
//在cellForItem方法中註冊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];
}
}