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);

重用标志

static NSString *  cellidentifier = @"cell";

注册重用标识符
    [cView registerClass:[MyCollectionViewCell class] forCellWithReuseIdentifier:cellidentifier];

Cell 重用

- (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;
}

UICollectionView cell 的布局