Adding a header to a collectionView object

#import "ProfileViewController.h"
#import "PhotoCell.h"
#import <Parse/Parse.h>
#import "headerView.h"


@interface ProfileViewController ()

@end

@implementation ProfileViewController


- (void)viewDidLoad
{
    [super viewDidLoad];



    self.edgesForExtendedLayout = UIRectEdgeNone;

    UICollectionViewFlowLayout *layout = [[UICollectionViewFlowLayout alloc]init];

    [layout setItemSize:CGSizeMake(306.0, 306.0)];
    [layout setMinimumInteritemSpacing:150.0];
    [layout setMinimumLineSpacing:50.0];



    UICollectionView *collectionView = [[UICollectionView alloc]initWithFrame:self.view.frame collectionViewLayout:layout];
    [collectionView setDataSource:self];
    [collectionView setDelegate:self];

    [collectionView registerClass:[PhotoCell class] forCellWithReuseIdentifier:@"jack"];
    [collectionView registerClass:[headerView class] forSupplementaryViewOfKind:UICollectionElementKindSectionHeader withReuseIdentifier:@"header"];



    [self.view addSubview:collectionView];


    [collectionView setBackgroundColor:[UIColor whiteColor]];



}

-(NSInteger) collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section {
    return 10;
}

- (UICollectionViewCell *) collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath {


    UICollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:@"jack" forIndexPath:indexPath];


    cell.backgroundColor = [UIColor lightGrayColor];

    return cell;
}

- (UICollectionReusableView *)collectionView:(UICollectionView *)collectionView viewForSupplementaryElementOfKind:(NSString *)kind atIndexPath:(NSIndexPath *)indexPath
{
    UICollectionReusableView *reusableview = nil;

    if (kind == UICollectionElementKindSectionHeader) {

        headerView *headerView = [collectionView dequeueReusableSupplementaryViewOfKind:UICollectionElementKindSectionHeader withReuseIdentifier:@"header" forIndexPath:indexPath];

    headerView.usernameLabel.text = @"hello";


        reusableview = headerView;
    }




    return reusableview;
}

@end