iOS注册collcetionViewFlowLayout

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"];

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