iOS开发异常丝滑的电商商品详情页

#import "ViewController.h"
#import <CSStickyHeaderFlowLayout/CSStickyHeaderFlowLayout.h>
#import "CSSectionHeader.h"
#import "CSParallaxHeader.h"

@interface ViewController ()<UICollectionViewDelegate,UICollectionViewDataSource,UICollectionViewDelegateFlowLayout>

@property (nonatomic,strong) UICollectionView *collectionView;
@property (nonatomic,strong) CSStickyHeaderFlowLayout *flowLayout;

@end

@implementation ViewController

- (void)viewDidLoad {
    [super viewDidLoad];
    
    self.navigationController.navigationBarHidden = YES;
    [self.view addSubview:self.collectionView];
    [self reloadLayout];
}

- (void)reloadLayout {
    CSStickyHeaderFlowLayout *layout = (id)self.flowLayout;
    if ([layout isKindOfClass:[CSStickyHeaderFlowLayout class]]) {
        layout.parallaxHeaderReferenceSize = CGSizeMake(self.view.frame.size.width, 200);
        layout.itemSize = CGSizeMake(layout.itemSize.height, layout.itemSize.height);
    }
}

#pragma mark - UICollectionViewDataSource
- (NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView {
    return 5;
}

- (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];
    cell.backgroundColor = [[UIColor redColor] colorWithAlphaComponent:0.1];
    return cell;
}

//设置headerView的宽高
- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout referenceSizeForHeaderInSection:(NSInteger)section {
    return CGSizeMake([UIScreen mainScreen].bounds.size.width, 100);
}

- (UICollectionReusableView *)collectionView:(UICollectionView *)collectionView viewForSupplementaryElementOfKind:(NSString *)kind atIndexPath:(NSIndexPath *)indexPath {
    if ([kind isEqualToString:UICollectionElementKindSectionHeader]) {
        CSSectionHeader *sectionHeader = [collectionView dequeueReusableSupplementaryViewOfKind:kind
                                                                            withReuseIdentifier:NSStringFromClass([CSSectionHeader class])
                                                                                   forIndexPath:indexPath];
        return sectionHeader;
    } else if ([kind isEqualToString:CSStickyHeaderParallaxHeader]) {
        UICollectionReusableView *reusableView = [collectionView dequeueReusableSupplementaryViewOfKind:kind
                                                                                    withReuseIdentifier:NSStringFromClass([CSParallaxHeader class])
                                                                                           forIndexPath:indexPath];
        return reusableView;
    }
    return nil;
}

///创建UICollectionView
- (UICollectionView *)collectionView {
    if (!_collectionView) {
        _collectionView = [[UICollectionView alloc] initWithFrame:self.view.bounds collectionViewLayout:self.flowLayout];
        _collectionView.showsHorizontalScrollIndicator = NO;
        _collectionView.delegate = self;
        _collectionView.dataSource = self;
        _collectionView.backgroundColor = nil;
        [_collectionView registerClass:[UICollectionViewCell class] forCellWithReuseIdentifier:NSStringFromClass([UICollectionViewCell class])];
        [_collectionView registerClass:[CSSectionHeader class] forSupplementaryViewOfKind:UICollectionElementKindSectionHeader withReuseIdentifier:NSStringFromClass([CSSectionHeader class])];
        [_collectionView registerClass:[CSParallaxHeader class] forSupplementaryViewOfKind:CSStickyHeaderParallaxHeader withReuseIdentifier:NSStringFromClass([CSParallaxHeader class])];
    }
    return _collectionView;
}

- (CSStickyHeaderFlowLayout *)flowLayout {
    if (!_flowLayout) {
        _flowLayout = [[CSStickyHeaderFlowLayout 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;
}

@end