UICollectionView顶部滑动

#import "ViewController.h"
#import "UIView+MJExtension.h"

@interface ViewController ()<UICollectionViewDelegate,UICollectionViewDataSource>

@property (nonatomic,strong) UICollectionView *collectionView;
@property (nonatomic,strong) UICollectionViewFlowLayout *flowLayout;
@property (nonatomic,strong) UIImageView *imageView;

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    
    [self.navigationController setNavigationBarHidden:YES animated:NO];
    [self.view addSubview:self.imageView];
    [self.view addSubview:self.collectionView];
}

#pragma mark - UICollectionViewDataSource
- (NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView {
    return 2;
}

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

- (__kindof UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath {
    UICollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:NSStringFromClass([UICollectionViewCell class]) forIndexPath:indexPath];
    if (indexPath.section == 0) {
        cell.backgroundColor = [UIColor lightGrayColor];
    } else {
        cell.backgroundColor = [UIColor purpleColor];
    }
    return cell;
}

///创建UICollectionView
- (UICollectionView *)collectionView {
    if (!_collectionView) {
        _collectionView = [[UICollectionView alloc] initWithFrame:self.view.bounds collectionViewLayout:self.flowLayout];
        [_collectionView setContentInset:UIEdgeInsetsMake(200, 0, 10, 0)];
        _collectionView.showsHorizontalScrollIndicator = NO;
        _collectionView.delegate = self;
        _collectionView.dataSource = self;
        _collectionView.backgroundColor = nil;
        [_collectionView registerClass:[UICollectionViewCell class] forCellWithReuseIdentifier:NSStringFromClass([UICollectionViewCell class])];
    }
    return _collectionView;
}

- (UICollectionViewFlowLayout *)flowLayout {
    if (!_flowLayout) {
        _flowLayout = [[UICollectionViewFlowLayout alloc] init];
        _flowLayout.minimumInteritemSpacing = 10;
        _flowLayout.minimumLineSpacing = 10;
        _flowLayout.sectionInset = UIEdgeInsetsMake(10, 10, 0, 10);
        _flowLayout.scrollDirection = UICollectionViewScrollDirectionVertical;
        _flowLayout.itemSize = CGSizeMake(150, 150);
    }
    return _flowLayout;
}

- (UIImageView *)imageView {
    if (!_imageView) {
        _imageView = [[UIImageView alloc] init];
        _imageView.frame = CGRectMake(0, 0, [UIScreen mainScreen].bounds.size.width, 250);
        _imageView.contentMode = UIViewContentModeScaleAspectFit;
        _imageView.image = [UIImage imageNamed:@"zrx4.jpg"];
        _imageView.backgroundColor = [UIColor orangeColor];
    }
    return _imageView;
}

- (void)scrollViewDidScroll:(UIScrollView *)scrollView {
    self.imageView.mj_y = -(scrollView.contentOffset.y+200);
}

@end