Application crash when set header of UICollectionView horizontally - ios

Question

I am pretty new in UICollectionView. And I am really tired to find out the solution. I am trying to add Header in 3 Horizontally Row. I am using Collection view flow layout.
Here is my code which I implement:
- (void)awakeFromNib {
self.collectionView.backgroundColor = [UIColor colorWithRed:204.0/255.0 green:204.0/255.0 blue:204.0/255.0 alpha:1.0];
self.collectionView.backgroundColor = [UIColor clearColor];
self.collectionView.backgroundView = [[UIView alloc] initWithFrame:CGRectZero];
UICollectionViewFlowLayout *flowLayout = [[UICollectionViewFlowLayout alloc] init];
flowLayout.scrollDirection = UICollectionViewScrollDirectionHorizontal;
flowLayout.itemSize = CGSizeMake(130.0, 170.0);
[self.collectionView setCollectionViewLayout:flowLayout];
// Register the colleciton cell
[_collectionView registerNib:[UINib nibWithNibName:#"ORGArticleCollectionViewCell" bundle:nil] forCellWithReuseIdentifier:#"ORGArticleCollectionViewCell"];
[self.collectionView registerClass:[_HeaderView class] forSupplementaryViewOfKind:UICollectionElementKindSectionHeader withReuseIdentifier:#"HeaderView"];
}
#pragma mark - UICollectionViewDataSource methods
- (NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView {
return 1;
}
- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section {
if (section == 0) {
return [self.collectionData count];
}
else if(section == 1)
{
return [self.collectionData1 count];
}
else
{
return [self.collectionData2 count];
}
}
- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
{
ORGArticleCollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:#"ORGArticleCollectionViewCell" forIndexPath:indexPath];
cell.articleTitle.text = [self.collectionData objectAtIndex:[indexPath row]];
NSString *URL = [self.collectionImageData objectAtIndex:indexPath.row];
[cell.articleImage setImageWithURL:[NSURL URLWithString:URL] placeholderImage:[UIImage imageNamed:#"profile-image-placeholder"]];
cell.articleImage.contentMode = UIViewContentModeScaleToFill;
cell.articlePrice.text = [self.collectionDataPric objectAtIndex:[indexPath row]];
return cell;
}
- (void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath
{
NSDictionary *cellData = [self.collectionData objectAtIndex:[indexPath row]];
[[NSNotificationCenter defaultCenter] postNotificationName:#"didSelectItemFromCollectionView" object:cellData];
}
- (CGFloat)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout minimumInteritemSpacingForSectionAtIndex:(NSInteger)section
{
return 0;
}
- (CGFloat)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout minimumLineSpacingForSectionAtIndex:(NSInteger)section
{
return 0;
}
- (UICollectionReusableView *)collectionView:(UICollectionView *)collectionView viewForSupplementaryElementOfKind:(NSString *)kind atIndexPath:(NSIndexPath *)indexPath {
UICollectionReusableView *headerView = [collectionView dequeueReusableSupplementaryViewOfKind:
UICollectionElementKindSectionHeader withReuseIdentifier:#"HeaderView" forIndexPath:indexPath];
UILabel *label = (UILabel *)[headerView viewWithTag:10];
if (!label) {
label = [[UILabel alloc] initWithFrame:CGRectInset(headerView.bounds, 5, 5)];
label.tag = 10;
label.font = [UIFont boldSystemFontOfSize:12];
label.textColor = [UIColor darkGrayColor];
[headerView addSubview:label];
}
label.text = [NSString stringWithFormat:#"Section %d", indexPath.section];
return headerView;
}
- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout referenceSizeForFooterInSection:(NSInteger)section {
CGSize headerSize = CGSizeMake(320, 44);
return headerSize;
}
My App crash in viewForSupplementaryElementOfKind method when I initialize the header view.
Following are the crash log:
Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'no UICollectionViewLayoutAttributes instance for -layoutAttributesForSupplementaryElementOfKind: UICollectionElementKindSectionHeader at path {length = 2, path = 0 - 0}'

Answer 1

The problem with your code is [headerView addSubview:label]; this is called only when label is equal to nil. but you have to call this statement every time when viewForSupplementaryElementOfKind is called.
Update your viewForSupplementaryElementOfKind function with following code.
- (UICollectionReusableView *)collectionView:(UICollectionView *)collectionView viewForSupplementaryElementOfKind:(NSString *)kind atIndexPath:(NSIndexPath *)indexPath {
UICollectionReusableView *headerView = [collectionView dequeueReusableSupplementaryViewOfKind:
UICollectionElementKindSectionHeader withReuseIdentifier:#"HeaderView" forIndexPath:indexPath];
UILabel *label = (UILabel *)[headerView viewWithTag:10];
if (!label) {
label = [[UILabel alloc] initWithFrame:CGRectInset(headerView.bounds, 5, 5)];
label.tag = 10;
label.font = [UIFont boldSystemFontOfSize:12];
label.textColor = [UIColor darkGrayColor];
}
label.text = [NSString stringWithFormat:#"Section %d", indexPath.section];
[headerView addSubview:label];
return headerView;
}