How to fix UICollectionView header issue? - ios

Question

I'm facing an issue where the header in a collection view is hiding part of the cell when an index title is selected.
It's important to indicate that the headers on the collection view are sticky.
For example, when "0" is selected, the following appears:
While I expect the following:
Notice that on the first screenshot the "0" section header is hiding the first line of the cell (which is "---- Cell Title ----").
I uploaded a sample app to Github that clearly demonstrates this issue. See https://github.com/yoasha/CollectionViewDemo
To reproduce, run the project with any iPhone simulator, select the "Collection View" option on the main page, and then tap the "0" or "1" index title.
For comparison with table view behavior, the sample app allows to select "Table View" on the main page. After that, selecting any index title will show a proper behavior of the table view in contrast to the collection view.
Any suggestions on how to fix this?
Following is the entire implementation of my collection view, which is also available on the above Github link.
#implementation MyCollectionViewController
static NSString * const reuseIdentifier = #"Cell";
- (void)viewDidLoad {
[super viewDidLoad];
UICollectionLayoutListConfiguration *config = [[UICollectionLayoutListConfiguration alloc] initWithAppearance:UICollectionLayoutListAppearancePlain];
config.headerMode = UICollectionLayoutListHeaderModeSupplementary;
self.collectionView.collectionViewLayout = [UICollectionViewCompositionalLayout layoutWithListConfiguration:config];
// Register cell classes
[self.collectionView registerClass:[UICollectionViewListCell class] forCellWithReuseIdentifier:reuseIdentifier];
[self.collectionView registerClass:[MyCollectionReusableViewHeader class]
forSupplementaryViewOfKind:UICollectionElementKindSectionHeader
withReuseIdentifier:#"header"];
}
#pragma mark <UICollectionViewDataSource>
- (NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView {
return self.dataModel.count;
}
- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section {
return self.dataModel.count;
}
- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath {
UICollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:reuseIdentifier forIndexPath:indexPath];
UIListContentConfiguration *config = [((UICollectionViewListCell *)cell) defaultContentConfiguration];
config.text = #"----- Cell Title -----\nsome info\nsome info\nsome info";
cell.contentConfiguration = config;
return cell;
}
- (UICollectionReusableView *)collectionView:(UICollectionView *)collectionView viewForSupplementaryElementOfKind:(NSString *)kind atIndexPath:(NSIndexPath *)indexPath {
if ([kind isEqualToString:UICollectionElementKindSectionHeader]) {
MyCollectionReusableViewHeader *header = [self.collectionView dequeueReusableSupplementaryViewOfKind:UICollectionElementKindSectionHeader
withReuseIdentifier:#"header"
forIndexPath:indexPath];
header.text = self.dataModel[indexPath.section];
return header;
}
return nil;
}
- (NSArray<NSString *> *)indexTitlesForCollectionView:(UICollectionView *)collectionView {
return self.dataModel;
}
- (NSIndexPath *)collectionView:(UICollectionView *)collectionView indexPathForIndexTitle:(NSString *)title atIndex:(NSInteger)index {
return [NSIndexPath indexPathWithIndex:index];
}
#end
self.dataModel is NSArray<NSString *> * assigned with #[#"0", #"1", #"2", #"3", #"4"]
I also found a report of this issue at UICollectionView: How can you make the index fast-scroll to the section header instead of the first section item?