self.arr = [[NSMutableArray alloc] init];
for (int i = 0; i < 9; i++) {
[self.arr addObject:[UIImage imageNamed:[[NSString alloc] initWithFormat:@"%d",i + 1]]];
}
UICollectionViewFlowLayout *flowLayout = [[UICollectionViewFlowLayout alloc] init];
[flowLayout setScrollDirection:UICollectionViewScrollDirectionVertical];
self.collectionView = [[UICollectionView alloc] initWithFrame:[[UIScreen mainScreen] bounds] collectionViewLayout:flowLayout];
[self.collectionView registerClass:[CollectionViewCell class] forCellWithReuseIdentifier:@"MyCollectionCell"];
self.collectionView.backgroundColor = [UIColor whiteColor];
[self.view addSubview:self.collectionView];
self.collectionView.dataSource = self;
self.collectionView.delegate = self;
[self.collectionView registerClass:[CollectionReusableView class] forSupplementaryViewOfKind:UICollectionElementKindSectionHeader withReuseIdentifier:@"Header"];
【微分享】：为明天做准备的最好方法就是集中你所有智慧，所有的热忱，把今天的工作做得尽善尽美，这就是你能应付未来的唯一方法!