如果实现了代理方法返回头部脚部视图，如果我只返回头部 脚部返回nil会直接崩溃

[zhangxiongwen]

//返回头脚视图

• (UICollectionReusableView *)collectionView:(UICollectionView *)collectionView viewForSupplementaryElementOfKind:(NSString *)kind atIndexPath:(NSIndexPath *)indexPath{ if ([kind isEqualToString:UICollectionElementKindSectionHeader]) { // CollectionHeaderAndFooterView *headerView = [collectionView dequeueReusableSupplementaryViewOfKind:UICollectionElementKindSectionHeader withReuseIdentifier:@"sectionHeader" forIndexPath:indexPath]; // headerView.titleLabel.text = @"头视图"; // headerView.titleLabel.backgroundColor = [UIColor orangeColor]; // return headerView; return nil;

  }else{ CollectionHeaderAndFooterView *footerView = [collectionView dequeueReusableSupplementaryViewOfKind:UICollectionElementKindSectionFooter withReuseIdentifier:@"sectionFooter" forIndexPath:indexPath]; footerView.titleLabel.text = @"脚视图"; footerView.titleLabel.backgroundColor = [UIColor cyanColor]; return footerView;

  } }