Dinesh Raja Dinesh Raja - 2 months ago 51
iOS Question

Removing empty space, if the section header is hidden in the UICollectionView

I have two sections in

UICollectionView
. I want to show a section header in
UICollectionView
for only 1st section. Not in 0th section.

So I tried to return
nil
in
viewForSupplementaryElementOfKind
: method for
section == 0
and returns view for the
section == 1
.

It crashes and shows below error:

Assertion failure in -[UICollectionView _createPreparedSupplementaryViewForElementOfKind:atIndexPath:withLayoutAttributes:applyAttributes]:


Here it is my code for the supplementary view.

- (UICollectionReusableView *)collectionView:(UICollectionView *)collectionView viewForSupplementaryElementOfKind:(NSString *)kind atIndexPath:(NSIndexPath *)indexPath
{
UICollectionReusableView *sectionHeader = nil;
if (kind == UICollectionElementKindSectionHeader && indexPath.section == 1) {
sectionHeader = [collectionView dequeueReusableSupplementaryViewOfKind:kind withReuseIdentifier:@"EventSectionHeader" forIndexPath:indexPath];
sectionHeader.layer.borderWidth = .5f;
sectionHeader.layer.borderColor = [UIColor colorWithRed:221.0 / 255.0 green:223.0 / 255.0 blue:220.0 / 255.0 alpha:1.0].CGColor;
}

return sectionHeader;
}


I have found that returning nil in
viewForSupplementaryElementOfKind:
method crashing for others too. Other answers suggesting to remove that method.

But I want to show section header for specific sections only. How to achieve that returning view for only one section? Thanks. Any help would be appreciated.

EDIT:

As @san said, I have updated code to hide the section header. It works. It hides the header. But I am still seeing the empty space in the place of section header. Expected results is there should be no space for section header, if it is hidden.

updated code:

- (UICollectionReusableView *)collectionView:(UICollectionView *)collectionView viewForSupplementaryElementOfKind:(NSString *)kind atIndexPath:(NSIndexPath *)indexPath
{

UICollectionReusableView *sectionHeader = nil;
if (kind == UICollectionElementKindSectionHeader) {
sectionHeader = [collectionView dequeueReusableSupplementaryViewOfKind:kind withReuseIdentifier:@"EventSectionHeader" forIndexPath:indexPath];
sectionHeader.layer.borderWidth = .5f;
sectionHeader.layer.borderColor = [UIColor colorWithRed:221.0 / 255.0 green:223.0 / 255.0 blue:220.0 / 255.0 alpha:1.0].CGColor;
if (indexPath.section == 0) {
sectionHeader.hidden = YES;

}else {
sectionHeader.hidden = NO;
}
}

return sectionHeader;
}


I even tried setting the frame for sectionHeader as @san said. But no luck. same result.

Answer

At last, I found an answer for my question. I have missed something. Anyway sorry for other fellow users.

I set the header height and width inside the below method till now as @san said.

- (UICollectionReusableView *)collectionView:(UICollectionView *)collectionView viewForSupplementaryElementOfKind:(NSString *)kind atIndexPath:(NSIndexPath *)indexPath

But It is not the correct method to set the frame size of supplementary views. Later I found another method inside the flowLayout, which helps me to set the header and footer sizes.

This really works well for me:

- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout referenceSizeForHeaderInSection:(NSInteger)section
{
    if (section == 0) {
        return CGSizeZero;
    }else {
        return CGSizeMake(CGRectGetWidth(collectionView.bounds), 135);
    }
}

UPDATE: Since someone questioned about my skill in comments, attaching Apple Documentation link for returning CGSizeZero in above method.