- (void)viewDidLoad{    [super viewDidLoad];    //创建一个布局方式    UICollectionViewFlowLayout *layout = [[UICollectionViewFlowLayout alloc] init];//    layout.scrollDirection = UICollectionViewScrollDirectionHorizontal;    layout.headerReferenceSize = CGSizeMake(320, 50);//header的size    layout.footerReferenceSize = CGSizeMake(320, 20);    layout.sectionInset = UIEdgeInsetsMake(0, 0, 20, 0);    //创建一个集合视图    UICollectionView *collectionView = [[UICollectionView alloc] initWithFrame:[UIScreen mainScreen].bounds collectionViewLayout:layout];    collectionView.dataSource = self;    collectionView.delegate = self;    [collectionView registerClass:[CustomCell class] forCellWithReuseIdentifier:@"cell"];    //注册header    [collectionView registerClass:[CustomHeaderView class] forSupplementaryViewOfKind:UICollectionElementKindSectionHeader withReuseIdentifier:@"header"];    //注册footer 增补视图    [collectionView registerClass:[UICollectionReusableView class] forSupplementaryViewOfKind:UICollectionElementKindSectionFooter withReuseIdentifier:@"footer"];        [self.view addSubview:collectionView];    [layout release];    [collectionView release];    // Do any additional setup after loading the view.}//定义展示的Section的个数- (NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView{    return 2;}//定义展示的UICollectionViewCell的个数- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section{    return 10;}//每个UICollectionViewCell展示的内容- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath{    static NSString *identifier = @"cell";    CustomCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:identifier forIndexPath:indexPath];    cell.titleLabel.text = [NSString stringWithFormat:@"%d",indexPath.row];    cell.backgroundColor = [UIColor orangeColor];    return cell;}//定义每个UICollectionView 中cell的大小- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout*)collectionViewLayout sizeForItemAtIndexPath:(NSIndexPath *)indexPath{    return CGSizeMake(100, 200);}//增补视图header与footer- (UICollectionReusableView *)collectionView:(UICollectionView *)collectionView viewForSupplementaryElementOfKind:(NSString *)kind atIndexPath:(NSIndexPath *)indexPath{    if (kind == UICollectionElementKindSectionHeader) {        CustomHeaderView *view = [collectionView dequeueReusableSupplementaryViewOfKind:kind withReuseIdentifier:@"header" forIndexPath:indexPath];        view.backgroundColor = [UIColor greenColor];        return view;    }else    {        UICollectionReusableView *view = [collectionView dequeueReusableSupplementaryViewOfKind:kind withReuseIdentifier:@"footer" forIndexPath:indexPath];        view.backgroundColor = [UIColor redColor];        return view;    }    }