how to display section headers when uicollectionviewcell is 0 number - objective-c

Question

I create one UICollectionView sticky header section with this : sticky header section but when my UICollectionViewCell is 0 number header section in hide like this picture :
in my picture show me one header section (index:2) and other header section is hidden. please guide me !!! I want other show like index 2.
this is my code:
- (void)viewDidLoad {
[super viewDidLoad];
self.view.backgroundColor = [UIColor whiteColor];
Flow *layout=[[Flow alloc] init];
//layout.sectionInset = UIEdgeInsetsMake(20,0,40,0);
//layout.itemSize = CGSizeMake(100,100);
_collect=[[UICollectionView alloc] initWithFrame:self.view.frame collectionViewLayout:layout];
_collect.backgroundColor = [UIColor clearColor];
[_collect setDataSource:self];
[_collect setDelegate:self];
[_collect registerClass:[HeaderView class] forSupplementaryViewOfKind:UICollectionElementKindSectionHeader withReuseIdentifier:#"HeaderView"];
[_collect registerClass:[CollectionViewCell class] forCellWithReuseIdentifier:#"cellIdentifier"];
[self.view addSubview:_collect];
//NSLog(#"%#",self.array);
}
- (NSMutableArray*)array {
if (!_array) {
_array = [NSMutableArray array];
for (NSInteger i=0; i<SectionNum; i++) {
//NSMutableArray *inner = [NSMutableArray arrayWithObject:#"0"];
[_array addObject:#"0"];
}
}
return _array;
}
- (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
- (NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView {
return SectionNum;
}
- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section{
if (section == 2) {
return 10;
} else
return 0;
}
- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath{
static NSString *identifier = #"cellIdentifier";
CollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:identifier forIndexPath:indexPath];
return cell;
}
- (UICollectionReusableView *)collectionView:(UICollectionView *)collectionView viewForSupplementaryElementOfKind:(NSString *)kind atIndexPath:(NSIndexPath *)indexPath
{
UICollectionReusableView *reusableview = nil;
if (kind == UICollectionElementKindSectionHeader) {
HeaderView *header = [_collect dequeueReusableSupplementaryViewOfKind:UICollectionElementKindSectionHeader withReuseIdentifier:#"HeaderView" forIndexPath:indexPath];
header.backgroundColor = [UIColor colorWithWhite:0.75 alpha:.9];
header.titleLabel.font = [UIFont systemFontOfSize:24];
header.titleLabel.textAlignment = NSTextAlignmentCenter;
header.titleLabel.text = [NSString stringWithFormat:#"%ld",indexPath.section];
reusableview = header;
}
if (kind == UICollectionElementKindSectionFooter) {
UICollectionReusableView *footerview = [collectionView dequeueReusableSupplementaryViewOfKind:UICollectionElementKindSectionFooter withReuseIdentifier:#"FooterView" forIndexPath:indexPath];
reusableview = footerview;
}
return reusableview;
}
- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout sizeForItemAtIndexPath:(NSIndexPath *)indexPath {
return CGSizeMake(100,100);
}
- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout referenceSizeForHeaderInSection:(NSInteger)section {
CGSize headerSize = CGSizeMake(320, 50);
return headerSize;
}