UICollectionView 集合视图

第二个参数 : cell 的布局
    UICollectionViewFlowLayout * flowLayout = [[UICollectionViewFlowLayout
                                                alloc]init];
滚动方向:
    flowLayout.scrollDirection = UICollectionViewScrollDirectionHorizontal ;
   

行间距(最小)
    flowLayout.minimumLineSpacing = 0;
  

列间距(最小)
    flowLayout.minimumInteritemSpacing = 30;
  

item大小
    flowLayout.itemSize = CGSizeMake(40, 30);
   

setcion 的边距
    flowLayout.sectionInset = UIEdgeInsetsMake(10, 10, 10, 10);
  

header 大小
    flowLayout.headerReferenceSize = CGSizeMake(320, 20);
  

footer大小
    flowLayout.footerReferenceSize = CGSizeMake(320, 20);
    

创建集合视图

UICollectionView * cView = [[UICollectionView alloc]initWithFrame:CGRectMake(0, 0, 320, 568  ) collectionViewLayout:flowLayout];
    cView.dataSource = self;  设置 dataSource 代理
    cView.delegate = self;      设置delegate 代理
    [self.view addSubview:cView];

集合视图cell 的数量

- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section
{
    return 100;
}

集合视图 设定 cell

- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
{
    MyCollectionViewCell * cell  = [collectionView dequeueReusableCellWithReuseIdentifier:cellidentifier forIndexPath:indexPath];
    cell.backgroundColor = [UIColor redColor];
    cell.textLavel.text = [NSString stringWithFormat:@"%ld",(long)indexPath.row];
    
    return cell;
}

Header 和 Footer  设置

- (UICollectionReusableView *)collectionView:(UICollectionView *)collectionView viewForSupplementaryElementOfKind:(NSString *)kind atIndexPath:(NSIndexPath *)indexPath
{
  if ([kind isEqualToString:UICollectionElementKindSectionHeader]) {
    
    HeaderView * headerView = [collectionView dequeueReusableSupplementaryViewOfKind:kind withReuseIdentifier:headeridentifier forIndexPath:indexPath];
    return headerView;
  }
 
    FooterView * footerView = [collectionView dequeueReusableSupplementaryViewOfKind:kind withReuseIdentifier:footeridentifier forIndexPath:indexPath];

    return footerView;
    
}

点击Collection 的cell 时 触发 此方法

#pragma mark - UICollectionViewDelegate
- (void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(NSIndexPath *)indexPath
{
    
}