先上效果图：

上代码

- (UICollectionView *)collectionView{    if(!_collectionView) {        UICollectionViewFlowLayout *layout = [[UICollectionViewFlowLayout alloc] init];        layout.minimumLineSpacing = 1;        layout.scrollDirection = UICollectionViewScrollDirectionHorizontal;        _collectionView = [[UICollectionView alloc] initWithFrame:CGRectMake(0, 100, self.view.frame.size.width, 100) collectionViewLayout:layout];        [self.view addSubview:_collectionView];        _collectionView.showsHorizontalScrollIndicator = NO;        _collectionView.delegate = self;        _collectionView.dataSource = self;                [_collectionView registerClass:[UICollectionViewCell class] forCellWithReuseIdentifier:@"UICollectionViewCell"];    }    return _collectionView;}复制代码

- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section{    return 20;}- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath{    UICollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:@"UICollectionViewCell" forIndexPath:indexPath];    UIImageView *imageView = [[UIImageView alloc] initWithFrame:cell.bounds];    imageView.image = [UIImage imageNamed:@"2623743-21d547b5c37a8f8e"];    [cell addSubview:imageView];        return cell;}- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout sizeForItemAtIndexPath:(NSIndexPath *)indexPath {    return CGSizeMake(100,150);}- (CGFloat)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout minimumInteritemSpacingForSectionAtIndex:(NSInteger)section {    return 5;}- (CGFloat)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout minimumLineSpacingForSectionAtIndex:(NSInteger)section {    return 5;}-(UIEdgeInsets)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout insetForSectionAtIndex:(NSInteger)section{    return UIEdgeInsetsMake(0, 5, 0, 0);}- (void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath{    NSLog(@"%ld",indexPath.row);}复制代码

就这样，很简单的，压根儿没有什么技术难度，我也只是回顾一下。