无法获取第一个单元格的正确索引

Question

尝试从 didSelectItemAtIndexPath 中的cellForItemAtIndexPath访问uilabel，但无法获取第一个单元格。 这是我的代码

在cellForItemAtIndexPath

UICollectionViewCell *cell=[collectionView dequeueReusableCellWithReuseIdentifier:@"Cell" forIndexPath:indexPath];
UILabel *featureName = [[UILabel alloc] initWithFrame:CGRectMake(5, 5, cell.frame.size.width-10, cell.frame.size.height-10)];
    featureName.tag = indexPath.row;
    [cell addSubview:featureName];

在didSelectItemAtIndexPath

UICollectionViewCell *cell = [collectionView cellForItemAtIndexPath:indexPath];
UILabel *featureName = [cell viewWithTag:indexPath.row];
featureName.textColor = [UIColor lightGrayColor];

可以从所有单元格中获取label.tag，但不能从第一个单元格中获取。点击第一个单元格时应用程序崩溃。

Answer 1

第一

行的indexPath.row为 0，但 0 不是有效的标记。我认为您应该只使用非零值。

尝试即

featureName.tag = indexPath.row + 1;
...
UILabel *featureName = [cell viewWithTag:indexPath.row+1];

Answer 2

cellForItemAtIndexPath

UICollectionViewCell *cell=[collectionView dequeueReusableCellWithReuseIdentifier:@"Cell" forIndexPath:indexPath];
UILabel *featureName = [[UILabel alloc] initWithFrame:CGRectMake(5, 5, cell.frame.size.width-10, cell.frame.size.height-10)];
    featureName.tag = indexPath.row + 1;
    [cell addSubview:featureName];

in didSelectItemAtIndexPath

UICollectionViewCell *cell = [collectionView cellForItemAtIndexPath:indexPath];
UILabel *featureName = [cell viewWithTag:indexPath.row + 1 ];
featureName.textColor = [UIColor lightGrayColor];

希望这能解决您的问题:)